WorldWideScience

Sample records for emission channeling photoluminescence

  1. Formation Mechanism of Carbogenic Nanoparticles with Dual Photoluminescence Emission

    KAUST Repository

    Krysmann, Marta J.

    2012-01-18

    We present a systematic investigation of the formation mechanism of carbogenic nanoparticles (CNPs), otherwise referred to as C-dots, by following the pyrolysis of citric acid (CA)-ethanolamine (EA) precursor at different temperatures. Pyrolysis at 180 °C leads to a CNP molecular precursor with a strongly intense photoluminescence (PL) spectrum and high quantum yield formed by dehydration of CA-EA. At higher temperatures (230 °C) a carbogenic core starts forming and the PL is due to the presence of both molecular fluorophores and the carbogenic core. CNPs that exhibit mostly or exclusively PL arising from carbogenic cores are obtained at even higher temperatures (300 and 400 °C, respectively). Since the molecular fluorophores predominate at low pyrolysis temperatures while the carbogenic core starts forming at higher temperatures, the PL behavior of CNPs strongly depends on the conditions used for their synthesis. © 2011 American Chemical Society.

  2. Photoluminescence emission spectra of Makrofol® DE 1-1 upon irradiation with ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    M. El Ghazaly

    Full Text Available Photoluminescence (PL emission spectra of Makrofol® DE 1-1 (bisphenol-A based polycarbonate upon irradiation with ultraviolet radiation of different wavelengths were investigated. The absorption-and attenuation coefficient measurements revealed that the Makrofol® DE 1-1 is characterized by high absorbance in the energy range 6.53–4.43 eV but for a lower energy than 4.43 eV, it is approximately transparent. Makrofol® DE 1-1 samples were irradiated with ultraviolet radiation of wavelength in the range from 250 (4.28 eV to 400 (3.10 eV nm in step of 10 nm and the corresponding photoluminescence (PL emission spectra were measured with a spectrofluorometer. It is found that the integrated counts and the peak height of the photoluminescence emission (PL bands are strongly correlated with the ultraviolet radiation wavelength. They are increased at the ultraviolet radiation wavelength 280 nm and have maximum at 290 nm, thereafter they decrease and diminish at 360 nm of ultraviolet wavelength. The position of the PL emission band peak was red shifted starting from 300 nm, which increased with the increase the ultraviolet radiation wavelength. The PL bandwidth increases linearly with the increase of the ultraviolet radiation wavelength. When Makrofol® DE 1-1 is irradiated with ultraviolet radiation of short wavelength (UVC, the photoluminescence emission spectra peaks also occur in the UVC but of a relatively longer wavelength. The current new findings should be considered carefully when using Makrofol® DE 1-1 in medical applications related to ultraviolet radiation. Keywords: Photoluminescence spectra, Makrofol® DE 1-1, UV–vis spectrophotometry, Attenuation coefficient, Ultraviolet radiation

  3. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

    Science.gov (United States)

    2012-01-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. PMID:23272786

  4. Photoluminescence emission spectra of Makrofol® DE 1-1 upon irradiation with ultraviolet radiation

    Science.gov (United States)

    El Ghazaly, M.; Aydarous, Abdulkadir

    Photoluminescence (PL) emission spectra of Makrofol® DE 1-1 (bisphenol-A based polycarbonate) upon irradiation with ultraviolet radiation of different wavelengths were investigated. The absorption-and attenuation coefficient measurements revealed that the Makrofol® DE 1-1 is characterized by high absorbance in the energy range 6.53-4.43 eV but for a lower energy than 4.43 eV, it is approximately transparent. Makrofol® DE 1-1 samples were irradiated with ultraviolet radiation of wavelength in the range from 250 (4.28 eV) to 400 (3.10 eV) nm in step of 10 nm and the corresponding photoluminescence (PL) emission spectra were measured with a spectrofluorometer. It is found that the integrated counts and the peak height of the photoluminescence emission (PL) bands are strongly correlated with the ultraviolet radiation wavelength. They are increased at the ultraviolet radiation wavelength 280 nm and have maximum at 290 nm, thereafter they decrease and diminish at 360 nm of ultraviolet wavelength. The position of the PL emission band peak was red shifted starting from 300 nm, which increased with the increase the ultraviolet radiation wavelength. The PL bandwidth increases linearly with the increase of the ultraviolet radiation wavelength. When Makrofol® DE 1-1 is irradiated with ultraviolet radiation of short wavelength (UVC), the photoluminescence emission spectra peaks also occur in the UVC but of a relatively longer wavelength. The current new findings should be considered carefully when using Makrofol® DE 1-1 in medical applications related to ultraviolet radiation.

  5. From photoluminescence emissions to plasmonic properties in platinum nanoparticles embedded in silica by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Bornacelli, J., E-mail: jhbornacelli@gmail.com [Instituto de Física, Universidad Nacional Autónoma de México, 04510 México D.F. (Mexico); Silva-Pereyra, H.G. [IPICyT, Division de Materiales Avanzados, Camino a la presa San Jose 2055, San Luis Potosi, S.L.P. 78216 (Mexico); Rodríguez-Fernández, L. [Instituto de Física, Universidad Nacional Autónoma de México, 04510 México D.F. (Mexico); Avalos-Borja, M. [IPICyT, Division de Materiales Avanzados, Camino a la presa San Jose 2055, San Luis Potosi, S.L.P. 78216 (Mexico); Centro de Nanociencias y Nanotecnologia – Universidad Nacional Autónoma de México, A. Postal 2681, Ensenada, B.C. (Mexico); Oliver, A. [Instituto de Física, Universidad Nacional Autónoma de México, 04510 México D.F. (Mexico)

    2016-11-15

    We have studied photoluminescence emission and optical absorption from platinum nanoparticles (Pt-nps) embedded in a silica matrix obtained by ion implantation. The Pt ions were implanted at 2 MeV and the nanoclusters were nucleated after thermal treatment at 600, 800, and 1100 °C under two different atmospheres: argon gas and a reducing atmosphere compound of H{sub 2} and N{sub 2}. The luminescent spectrum is broader (400–600 nm) and is peaked at 530 nm, but its intensity decreases as the annealing temperature increases. However, at high annealing temperatures, a Mie resonance at 220 nm emerges in the absorption spectrum. We then observed a transition between two optical properties in a system of Pt-nps embedded in silica: from molecule-like properties such as photoluminescence emission to localized surface plasmon absorption. - Highlights: • Photoluminescence (PL) from ion-implanted Pt-nps in silica have been demonstrated. • PL properties depend on the temperature and atmosphere used to form Pt-nps in silica. • PL is quenched for samples with larger Pt-nps, however a Mie resonance appear. • Transition from molecule-like to bulk-like properties of Pt-nps in silica is reveled.

  6. Enhancement of field emission and photoluminescence properties of graphene-SnO2 composite nanostructures.

    Science.gov (United States)

    Ding, Jijun; Yan, Xingbin; Li, Jun; Shen, Baoshou; Yang, Juan; Chen, Jiangtao; Xue, Qunji

    2011-11-01

    In this study, the SnO(2) nanostructures and graphene-SnO(2) (G-SnO(2)) composite nanostructures were prepared on n-Si (100) substrates by electrophoretic deposition and magnetron sputtering techniques. The field emission of SnO(2) nanostructures is improved largely by depositing graphene buffer layer, and the field emission of G-SnO(2) composite nanostructures can also further be improved by decreasing sputtering time of Sn nanoparticles to 5 min. The photoluminescence (PL) spectra of the SnO(2) nanostructures revealed multipeaks, which are consistent with previous reports except for a new peak at 422 nm. Intensity of six emission peaks increased after depositing graphene buffer layer. Our results indicated that graphene can also be used as buffer layer acting as interface modification to simultaneity improve the field emission and PL properties of SnO(2) nanostructures effectively.

  7. Photoluminescence emission at room temperature in zinc oxide nano-columns

    International Nuclear Information System (INIS)

    Rocha, L.S.R.; Deus, R.C.; Foschini, C.R.; Moura, F.; Garcia, F. Gonzalez; Simões, A.Z.

    2014-01-01

    Highlights: • ZnO nanoparticles were obtained by microwave-hydrothermal method. • X-ray diffraction reveals a hexagonal structure. • Photoluminescence emission evidenced two absorption peaks, at around 480 nm and 590 nm wavelengths. - Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline zinc oxide (ZnO) nano-columns at the temperature of 120 °C with a soaking time of 8 min. ZnO nano-columns were characterized by using X-ray analyses (XRD), infrared spectroscopy (FT-IR), thermogravimetric analyses (TG-DTA), field emission gun and transmission electron microscopy (FEG-SEM and TEM) and photoluminescence properties (PL). XRD results indicated that the ZnO nano-columns are free of any impurity phase and crystallize in the hexagonal structure. Typical FT-IR spectra for ZnO nano-columns presented well defined bands, indicating a substantial short-range order in the system. PL spectra consist of a broad band at 590 nm and narrow band at 480 nm corresponding to a near-band edge emission related to the recombination of excitons and level emission related to structural defects. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain ZnO nano-columns in the temperature of 120 °C for 8 min

  8. Photoluminescence emission at room temperature in zinc oxide nano-columns

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, L.S.R.; Deus, R.C. [Universidade Estadual Paulista – Unesp, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil); Foschini, C.R. [Universidade Estadual Paulista – Unesp, Instituto de Química, Laboratório Interdisciplinar em Cerâmica (LIEC), Rua Professor Francisco Degni s/n, CEP 14800-90 Araraquara, SP (Brazil); Moura, F.; Garcia, F. Gonzalez [Universidade Federal de Itajubá – Unifei, Campus Itabira, Rua São Paulo, 377, Bairro Amazonas, CEP 35900-37 Itabira, MG (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista – Unesp, Faculdade de Engenharia de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Portal das Colinas, CEP 12516-410 Guaratinguetá, SP (Brazil)

    2014-02-01

    Highlights: • ZnO nanoparticles were obtained by microwave-hydrothermal method. • X-ray diffraction reveals a hexagonal structure. • Photoluminescence emission evidenced two absorption peaks, at around 480 nm and 590 nm wavelengths. - Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline zinc oxide (ZnO) nano-columns at the temperature of 120 °C with a soaking time of 8 min. ZnO nano-columns were characterized by using X-ray analyses (XRD), infrared spectroscopy (FT-IR), thermogravimetric analyses (TG-DTA), field emission gun and transmission electron microscopy (FEG-SEM and TEM) and photoluminescence properties (PL). XRD results indicated that the ZnO nano-columns are free of any impurity phase and crystallize in the hexagonal structure. Typical FT-IR spectra for ZnO nano-columns presented well defined bands, indicating a substantial short-range order in the system. PL spectra consist of a broad band at 590 nm and narrow band at 480 nm corresponding to a near-band edge emission related to the recombination of excitons and level emission related to structural defects. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain ZnO nano-columns in the temperature of 120 °C for 8 min.

  9. From photoluminescence to thermal emission: Thermally-enhanced PL (TEPL) for efficient PV (Conference Presentation)

    Science.gov (United States)

    Manor, Assaf; Kruger, Nimrod; Martin, Leopoldo L.; Rotschild, Carmel

    2016-09-01

    The Shockley-Queisser efficiency limit of 40% for single-junction photovoltaic (PV) cells is mainly caused by the heat dissipation accompanying the process of electro-chemical potential generation. Concepts such as solar thermo-photovoltaics (STPV) aim to harvest this heat loss by the use of a primary absorber which acts as a mediator between the sun and the PV, spectrally shaping the light impinging on the cell. However, this approach is challenging to realize due to the high operating temperatures of above 2000K required in order to generate high thermal emission fluxes. After over thirty years of STPV research, the record conversion efficiency for STPV device stands at 3.2% for 1285K operating temperature. In contrast, we recently demonstrated how thermally-enhanced photoluminescence (TEPL) is an optical heat-pump, in which photoluminescence is thermally blue-shifted upon heating while the number of emitted photons is conserved. This process generates energetic photon-rates which are comparable to thermal emission in significantly reduced temperatures, opening the way for a TEPL based energy converter. In such a device, a photoluminescent low bandgap absorber replaces the STPV thermal absorber. The thermalization heat induces a temperature rise and a blue-shifted emission, which is efficiently harvested by a higher bandgap PV. We show that such an approach can yield ideal efficiencies of 70% at 1140K, and realistic efficiencies of almost 50% at moderate concentration levels. As an experimental proof-of-concept, we demonstrate 1.4% efficient TEPL energy conversion of an Nd3+ system coupled to a GaAs cell, at 600K.

  10. Analysis of polarized photoluminescence emission of ordered III–V semiconductor quaternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prutskij, Tatiana, E-mail: tatiana.prutskij@correo.buap.mx [Instituto de Ciencias, BUAP, Privada 17 Norte, No 3417, Col. San Miguel Huyeotlipan, 72050 Puebla, Pue., México (Mexico); Makarov, Nykolay, E-mail: nykolay.makarov@correo.buap.mx [Instituto de Ciencias, BUAP, Privada 17 Norte, No 3417, Col. San Miguel Huyeotlipan, 72050 Puebla, Pue., México (Mexico); Attolini, Giovanni, E-mail: giovanni@imem.cnr.it [IMEM/CNR, Parco Area delle Scienze 37/A, 43010 Parma (Italy)

    2016-04-15

    Ternary and quaternary III–V alloys obtained by metal-organic vapor-phase epitaxy (MOVPE) grow very often with some degree of atomic ordering. Atomic ordering reduces the symmetry of the crystal lattice and thus drastically changes optical properties of the alloy. Moreover, the photoluminescence (PL) emission becomes polarized and its study helps to understand the atomic arrangement within the crystal lattice. In this work we experimentally studied the polarization of the PL emission from different crystallographic planes of several quaternary III–V semiconductor alloys grown on GaAs substrates by MOVPE. We compare the measured PL emission polarization angular patterns with those calculated with a model made for ternary alloys and discuss the limits of application of this model for quaternaries. It is found that the experimentally obtained polarization patterns are consistent with the existence of different ordering crystallographic planes for III- and for V-group atoms.

  11. A novel approach to obtain highly intense self-activated photoluminescence emissions in hydroxyapatite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Thales R. [CDMF-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); QIO-UJI, Universitat Jaume I, 12071 Castellón (Spain); Sczancoski, Júlio C. [CDMF-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Beltrán-Mir, Héctor [QIO-UJI, Universitat Jaume I, 12071 Castellón (Spain); Nogueira, Içamira C. [PPGEM-IFMA, Instituto Federal de Educação, Ciência e Tecnologia do Maranhão, 65030-005 São Luís, MA (Brazil); Li, Máximo S. [IFSC-USP, Universidade de São Paulo, P.O. Box 369, 13560-970 São Carlos, SP (Brazil); Andrés, Juan [QFA-UJI, Universitat Jaume I, 12071 Castellón (Spain); Cordoncillo, Eloisa [QIO-UJI, Universitat Jaume I, 12071 Castellón (Spain); Longo, Elson, E-mail: elson.liec@gmail.com [CDMF-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil)

    2017-05-15

    Defect-related photoluminescence (PL) in materials have attracted interest for applications including near ultraviolet (NUV) excitable light-emitting diodes and in biomedical field. In this paper, hydroxyapatite [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}] nanorods with intense PL bands (bluish- and yellowish-white emissions) were obtained when excited under NUV radiation at room temperature. These nanoparticles were synthesized via chemical precipitation at 90 °C followed by distinct heat treatments temperatures (200–800 °C). Intense and broad emission profiles were achieved at 350 °C (380–750 nm) and 400 °C (380–800 nm). UV–Vis spectroscopy revealed band gap energies (5.58–5.78 eV) higher than the excitation energies (~3.54 and ~2.98 eV at 350 and 415 nm, respectively), confirming the contribution of defect energy levels within the forbidden zone for PL emissions. The structural features were characterized by X-ray diffraction, Rietveld refinement, thermogravimetric analysis, and Fourier transform infrared spectroscopy. By means of these techniques, the relation between structural order-disorder induced by defects, chemical reactions at both lattice and surface of the materials as well as the PL, without activator centers, was discussed in details. - Graphical abstract: The self-activated photoluminescence emissions of chemically precipitated hydroxyapatite nanorods were improved by different heat treatment temperatures. - Highlights: • HA nanorods were synthesized with improved self-activated PL at room temperature. • PL profile and intensity dependents on the temperature of posterior heat treatments. • Bluish- and yellowish-white emissions under NUV excitation (350 and 415 nm). • Broad and intense profiles achieved at 350 °C (380–750 nm) and 400 °C (380–800 nm). • PL from the e′–h{sup •} recombination between defect energy levels within the band gap.

  12. Synthesis of silver hollow nanoparticles and observation of photoluminescence emission properties

    International Nuclear Information System (INIS)

    Desarkar, H.S.; Kumbhakar, P.; Mitra, A.K.

    2013-01-01

    Preparation of hollow silver nanoparticles (HSNs) along-with solid silver nanoparticles are reported by Nd:YAG laser ablation of solid silver target immersed in water medium with a laser ablation time (LAT) duration of 50 min and with the incident laser fluence of 151 J/cm 2 . It is found that only solid silver nanoparticles are produced when the experiment is carried out with smaller values of LAT duration. The synthesized samples are characterized by using transmission electron microscopy and UV–Visible absorption spectroscopy. The UV–Visible absorption spectra of the samples show sharp absorptions in the ultraviolet and in visible regions due to interband transition and surface plasmon resonance oscillations in Ag nanoparticles, respectively. It is found that all samples exhibit photoluminescence (PL) emission, at room temperature, in the UV–Visible region peaked at ∼346 nm, due to the recombination of electrons with holes from sp conduction band to d band of Ag. The sample containing HSNs exhibits strong PL emission and the value of peak PL emission intensity is enhanced by the factor of 2.4 in comparison to that obtained from the sample synthesized with LAT duration of 20 min. The synthesized HSNs may find applications in catalysis and in chemical sensing. - Highlights: ►Hollow silver nanoparticles of 15–60 nm particle sizes are prepared by laser ablation. ►Prepared Ag nanoparticles show sharp absorptions in the UV and visible regions. ►Strong interband transition along-with SPR oscillations is reported. ►Enhancement (2.4 times) in photoluminescence emission in the UV region is reported.

  13. Photoluminescence and cathodoluminescence of Mn doped zinc silicate nanophosphors for green and yellow field emissions displays

    Science.gov (United States)

    Omri, K.; Alyamani, A.; Mir, L. El

    2018-02-01

    Mn2+-doped Zn2SiO4 (ZSM2+) was synthesized by a facile sol-gel technique. The obtained samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, photoluminescence (PL) and cathodoluminescence (CL) techniques. Under UV excitation, spectra showed that the α-ZSM2+ phosphor exhibited a strong green emission around 525 nm and reached the highest luminescence intensity with the Mn doping concentration of 5 at.%. However, for the β-ZSM2+ phase, an interesting yellow emission band centered at 575 nm of Mn2+ at the Zn2+ tetrahedral sites was observed. In addition, an unusual red shift with increasing Mn2+ content was also found and attributed to an exchange interaction between Mn2+. Both PL and CL spectra exhibit an intense green and yellow emission centered at 525 and 573 nm, respectively, due to the 4T1 (4G)-6A1 (6S) transition of Mn2+. Furthermore, these results indicated that the Mn2+-doped zinc silicate phosphors may have potential applications in green and yellow emissions displays like field emission displays (FEDs).

  14. Unusual photoluminescence phenomena : New insights in Stokes and anti-Stokes emission

    NARCIS (Netherlands)

    de Jong, M.

    2017-01-01

    Photoluminescent materials are applied in many devices that we use in our daily lives. For example in fluorescent lamps and LED-lamps, photoluminescent materials convert the source light to create white light. Photoluminescent materials can also play a role in more complicated devices, as for

  15. Strong white light emission from a processed porous silicon and its photoluminescence mechanism

    International Nuclear Information System (INIS)

    Karacali, T.; Cicek, K.

    2011-01-01

    We have prepared various porous silicon (PS) structures with different surface conditions (any combination of oxidation, carbonization as well as thermal annealing) to increase the intensity of photoluminescence (PL) spectrum in the visible range. Strong white light (similar to day-light) emission was achieved by carrying out thermal annealing at 1100 deg. C after surface modification with 1-decene of anodic oxidized PS structures. Temperature-dependent PL measurements were first performed by gradually increasing the sample temperature from 10 to 300 K inside a cryostat. Then, we analyzed the measured spectrum of all prepared samples. After the analysis, we note that throughout entire measured spectrum, only two main peaks corresponding to blue and green-orange emission lines (which can be interpreted by quantum size effect and/or configuration coordinate model) were seem to be predominant for all temperature range. To further reveal and analysis these peaks, finally, measured data were inputted into the formula of activation energy of thermal excitation. We found that activation energies of blue and green-orange lines were approximately 49.3 and 44.6 meV, respectively. - Highlights: →Light emitting devices based on silicon technology are of great interest in illumination and display applications. → We have achieved strong white light (similar to day-light) emission from porous silicon. → The most important impact of carbonization on porous silicon and post annealing is the enhancement of room temperature luminescence.

  16. Color-tunable mixed photoluminescence emission from Alq3 organic layer in metal-Alq3-metal surface plasmon structure

    OpenAIRE

    Chen, Nai-Chuan; Liao, Chung-Chi; Chen, Cheng-Chang; Fan, Wan-Ting; Wu, Jin-Han; Li, Jung-Yu; Chen, Shih-Pu; Huang, Bohr-Ran; Lee, Li-Ling

    2014-01-01

    This work reports the color-tunable mixed photoluminescence (PL) emission from an Alq3 organic layer in an Au-Alq3-Au plasmonic structure through the combination of organic fluorescence emission and another form of emission that is enabled by the surface plasmons in the plasmonic structure. The emission wavelength of the latter depends on the Alq3 thickness and can be tuned within the Alq3 fluorescent spectra. Therefore, a two-color broadband, color-tunable mixed PL structure was obtained. Ob...

  17. Temperature-Dependent Photoluminescence Emission from Unstrained and Strained GaSe Nanosheets

    Directory of Open Access Journals (Sweden)

    Duan Zhang

    2017-11-01

    Full Text Available Two-dimensional AIIIBVI layered semiconductors have recently attracted great attention due to their potential applications in piezo-phototronics and optoelectronics. Here, we report the temperature-dependent photoluminescence (PL of strained and unstrained GaSe flakes. It is found that, as the temperature increases, the PL from both the strained (wrinkled and unstrained (flat positions show a prominent red-shift to low energies. However, for the flat case, the slope of PL energy versus temperature at the range of 163–283 K is about −0.36 meV/K, which is smaller than that of the wrinkled one (−0.5 meV/K. This is because more strain can be introduced at the freestanding wrinkled position during the temperature increase, thus accelerates the main PL peak (peak I, direct band gap transition shift to lower energy. Additionally, for the wrinkled sheet, three new exciton states (peaks III, IV, and V appear at the red side of peak I, and the emission intensity is highly dependent on the temperature variation. These peaks can be attributed to the bound exciton recombination. These findings demonstrate an interesting route for optical band gap tuning of the layered GaSe sheet, which are important for future optoelectronic device design.

  18. Reversible Concentration-Dependent Photoluminescence Quenching and Change of Emission Color in CsPbBr3 Nanowires and Nanoplatelets.

    Science.gov (United States)

    Di Stasio, Francesco; Imran, Muhammad; Akkerman, Quinten A; Prato, Mirko; Manna, Liberato; Krahne, Roman

    2017-06-15

    We discuss the photoluminescence (PL) of quantum-confined CsPbBr 3 colloidal nanocrystals of two different shapes (nanowires and nanoplatelets) at different concentrations in solution and in solid-state films. Upon increasing the nanocrystal concentration in solution, a constant drop in photoluminescence quantum yield is observed, accompanied by a significant PL red shift. This effect is reversible, and the original PL can be restored by diluting to the original concentration. We show that this effect can be in part attributed to self-absorption and partly to aggregation. In particular, for nanoplatelets, where the aggregation is mostly irreversible, while the self-absorption effect is reversible, the two contributions can be well separated. Finally, when dry solid-state films are prepared, the emission band is shifted into the green spectral region, close to the bulk CsPbBr 3 band gap, thus preventing blue emission from such films.

  19. Color-tunable mixed photoluminescence emission from Alq3 organic layer in metal-Alq3-metal surface plasmon structure.

    Science.gov (United States)

    Chen, Nai-Chuan; Liao, Chung-Chi; Chen, Cheng-Chang; Fan, Wan-Ting; Wu, Jin-Han; Li, Jung-Yu; Chen, Shih-Pu; Huang, Bohr-Ran; Lee, Li-Ling

    2014-01-01

    This work reports the color-tunable mixed photoluminescence (PL) emission from an Alq3 organic layer in an Au-Alq3-Au plasmonic structure through the combination of organic fluorescence emission and another form of emission that is enabled by the surface plasmons in the plasmonic structure. The emission wavelength of the latter depends on the Alq3 thickness and can be tuned within the Alq3 fluorescent spectra. Therefore, a two-color broadband, color-tunable mixed PL structure was obtained. Obvious changes in the Commission Internationale d'Eclairage (CIE) coordinates and the corresponding emission colors of Au-Alq3-Au samples clearly varied with the Alq3 thickness (90, 130, and 156 nm).

  20. Proportion of influence phases anatase and rutile TiO_2 in the photoluminescence 538 nm emission wavelength

    International Nuclear Information System (INIS)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M.; Viana, R.S.; Junior, S.A.

    2016-01-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO_2 molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm"3 and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  1. Enhancing the Photoluminescence Emission of Conjugated MEH-PPV by Light Processing

    KAUST Repository

    Botiz, Ioan

    2014-04-09

    We show here that treatment of thin films of conjugated polymers by illumination with light leads to an increase of the intensity of their photoluminescence by up to 42%. The corresponding enhancement of absorbance was much less pronounced. We explain this significant enhancement of photoluminescence by a planarization of the conjugated polymer chains induced by photoexcitations even below the glass transition temperature, possibly due to an increased conjugation length. Interestingly, the photoluminescence remains at the enhanced level for more than 71 h after treatment of the films by illumination with light, likely due to the fact that below the glass transition temperature no restoring force could return the conjugated chains into their initial conformational state. © 2014 American Chemical Society.

  2. Excitation wavelength dependent photoluminescence emission behavior, UV induced photoluminescence enhancement and optical gap tuning of Zn0.45Cd0.55S nanoparticles for optoelectronic applications

    Science.gov (United States)

    Osman, M. A.; Abd-Elrahim, A. G.

    2018-03-01

    In the present study, we investigate the excitation wavelength (λex) dependent photoluminescence (PL) behavior in Zn0.45Cd0.55S nanoparticles. The deconvoluted PL emission bands for nanopowders and nanocolloids reveal noticeable spectral blue shift with decreasing λex accompanied by intensity enhancement. This unusual behavior is explained in terms of selective particle size distribution in nanostructures, advancing of fast ionization process at short λex; and solvation process in polar solvent. In addition, we attributed the UV-induced PL intensity enhancement and blue shift of the optical gap to the reduction in particle size by photo-corrosion process associated with the improvement in the quantum size effect; surface modification due to cross-linkage improvement of capping molecules at NPs surface; the creation of new radiative centers and the formation of photo-passivation layers from ZnSO4 and CdSO4, and photo-enhanced oxygen adsorption on Zn0.45Cd0.55S nanoparticles surface.

  3. Modification of erbium photoluminescence excitation spectra for the emission wavelength 1.54 μm in mesoscopic structures

    International Nuclear Information System (INIS)

    Gaponenko, N.V.; Unuchak, D.M.; Mudryi, A.V.; Malyarevich, G.K.; Gusev, O.B.; Stepikhova, M.V.; Krasilnikova, L.V.; Stupak, A.P.; Kleshcheva, S.M.; Samoilovich, M.I.; Tsvetkov, M.Yu.

    2006-01-01

    Photoluminescence excitation (PLE) spectra for the emission wavelength 1.54 μm were studied for erbium-doped xerogels embedded in artificial opals and porous anodic alumina films. Opals were chosen with photonic stop-band in green spectral range, where excitation of 1.54 μm occurs most efficiently. In comparison to the structure erbium-doped titania xerogel/porous anodic alumina/silicon the photoluminescence excitation spectra for 1.54 μm emission wavelength significantly changes for the same xerogels embedded in artificial opals. Enhancement of erbium-related 1.54 μm emission was observed from the structure Fe 2 O 3 xerogel/porous anodic alumina fabricated on silicon, having some incompletely anodized aluminium, under excitation with either the lasing source at 532 nm or xenon lamp. Evident difference in PLE spectra for erbium doped TiO 2 and Fe 2 O 3 xerogels in porous anodic alumina is observed

  4. Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Zhitao [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Banishev, Alexandr A.; Christensen, James; Dlott, Dana D. [School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N., E-mail: naresh.thadhani@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Zhou, Min [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

    2016-07-28

    The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

  5. Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

    International Nuclear Information System (INIS)

    Kang, Zhitao; Banishev, Alexandr A.; Christensen, James; Dlott, Dana D.; Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N.; Xiao, Pan; Zhou, Min

    2016-01-01

    The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

  6. Splitting of photoluminescent emission from nitrogen–vacancy centers in diamond induced by ion-damage-induced stress

    International Nuclear Information System (INIS)

    Olivero, P; Bosia, F; Fairchild, B A; Gibson, B C; Greentree, A D; Spizzirri, P; Prawer, S

    2013-01-01

    We report a systematic investigation on the spectral splitting of negatively charged, nitrogen–vacancy (NV − ) photoluminescent emission in single-crystal diamond induced by strain engineering. The stress fields arise from MeV ion-induced conversion of diamond to amorphous and graphitic material in regions proximal to the centers of interest. In low-nitrogen sectors of a high-pressure–high-temperature diamond, clearly distinguishable spectral components in the NV − emission develop over a range of ∼4.8 THz corresponding to distinct alignment of sub-ensembles which were mapped with micron spatial resolution. This method provides opportunities for the creation and selection of aligned NV − centers for ensemble quantum information protocols. (paper)

  7. Er{sup 3+}-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

    Energy Technology Data Exchange (ETDEWEB)

    Morea, R. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Miguel, A. [Departamento de Física Aplicada I, Escuela Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alda. Urquijo s/n, 48013 Bilbao (Spain); Fernandez, T.T. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Maté, B. [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Ferrer, F.J. [Centro Nacional de Aceleradores, Univ. Sevilla-CSIC, Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Maffiotte, C. [CIEMAT, Departamento de Tecnología, Av. Complutense 40, 28040 Madrid (Spain); Fernandez, J.; Balda, R. [Departamento de Física Aplicada I, Escuela Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alda. Urquijo s/n, 48013 Bilbao (Spain); Materials Physics Center CSIC-UPV/EHU and Donostia International Physics Center, 20018 San Sebastian (Spain); Gonzalo, J., E-mail: j.gonzalo@csic.es [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain)

    2016-02-15

    Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O{sub 2} atmosphere from an Er-doped TeO{sub 2}–ZnO–ZnF{sub 2} bulk glass. Thin film glasses present high refractive index (n≥1.95) and good transparency (T≥80%) in the visible (λ>400 nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 μm is poor. Thermal annealing at moderate temperatures (T≤315 °C), well below glass crystallization, increases the PL intensity by more than one order of magnitude as well as the PL lifetime up to τ≈3.3 ms. Film glasses present a larger fraction of TeO{sub 3} trigonal pyramids than the bulk glass and a very large OH{sup −} content. The structure and composition of film glasses do not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OH{sup −} content. - Highlights: • Transparent Er-doped fluorotellurite films are produced by pulsed laser deposition. • Post-deposition thermal treatments are required to activate Er{sup 3+} photoluminescence. • {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} emission spectrum is similar for bulk and annealed film glasses. • {sup 4}I{sub 13/2} level fluorescence decay is shorter in annealed films than in bulk glasses. • Photoluminescence response relates to hydroxyl groups concentration in film glasses.

  8. Diamond photonic crystal slab: leaky modes and modified photoluminescence emission of surface-deposited quantum dots

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Babchenko, Oleg; Varga, Marián; Kromka, Alexander; Čtyroký, Jiří; Pelant, Ivan

    2012-01-01

    Roč. 2, Dec (2012), s. 1-6 ISSN 2045-2322 R&D Projects: GA ČR(CZ) GAP108/11/0794; GA AV ČR(CZ) IAA101120804; GA AV ČR KJB100100903; GA ČR(CZ) GAP205/10/0046 Grant - others:AVČR(CZ) M100100902 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z20670512 Keywords : photonic crystal * diamond * photoluminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.927, year: 2012 http://www.nature.com/srep/2012/121203/srep00914/full/srep00914.html

  9. Blue to Yellow Photoluminescence Emission and Photocatalytic Activity of Nitrogen Doping in TiO2 Powders

    Directory of Open Access Journals (Sweden)

    Gabriela Byzynski

    2015-01-01

    Full Text Available The defects caused by doping are important for understanding the increased photocatalytic activities of TiO2:N in organic reactions and in the evaluation of OH radical production after doping. TiO2:N was therefore synthesized using a modified polymeric method and N doping was performed by calcination with urea. The resulting powders were characterized using field emission scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, Raman spectroscopy, Fourier transformation infrared spectroscopy, and photoluminescence emission spectroscopy (PL. N doping did not alter the morphology of the nanoparticles, and the anatase phase predominated, with the retention of the rutile phase. The band gap values, superficial areas, and crystallite sizes of the powders decreased after doping. The PL results showed an additional energy level in the TiO2:N band gap structure as a result of TiO2 lattice defects caused by doping. At low N contents, the powders showed continuous emissions from the blue region to the yellow region and a high N content shifted the PL emissions to the red region. These results suggest that the use of these powders could increase the efficiencies of solar cells and water-splitting processes. The photocatalytic activity of the powders under UVC illumination was confirmed for different organic dye molecules. The OH radical production did not change extensively after doping, as shown by experiments with terephthalic acid, and higher photocatalytic efficiencies in Rhodamine-B degradation under UVC illumination were achieved using the doped samples.

  10. Quantitative analysis of the self-absorption and reemission effects on the emission spectrum of photoluminescence in right-angle excitation—detection configuration

    International Nuclear Information System (INIS)

    Wang Zhen-Hua; Wu Yu-E; Zhang Xin-Zheng; Yun Zhi-Qiang; Li Wei; Xu Jing-Jun

    2013-01-01

    A theoretical approach based on differential radiative transport is proposed to quantitatively analyze the self-absorption and reemission effects on the emission spectrum for right angle excitation—detection photoluminescence measurements, and the wavelength dependence of the reemission effect is taken into account. Simulations and experiments are performed using rhodamine 6G solutions in ethanol as model samples. It is shown that the self-absorption effect is the dominant effect on the detected spectrum by inducing pseudo red-shift and reducing total intensity; whereas the reemission effect partly compensates for signal decrease and also results in an apparent signal gain at the wavelengths without absorption. Both effects decrease with the decrease in the sample concentration and the propagation distance of the emission light inside the sample. We therefore suggest that diluted solutions are required for accurate photoluminescence spectrum measurements and photoluminescence-based measurements

  11. Emission channeling lattice location experiments with short-lived isotopes

    CERN Multimedia

    Wahl, U; Ronning, C R

    2007-01-01

    Emission channeling with position-sensitive detectors is a well-established technique at ISOLDE for studying the lattice location of radioactive impurities implanted into single crystals. In the case of electron emitting isotopes, however, due to count rate and noise-related limitations of the detection systems, the technique was restricted to isotopes with half lives above 6 h and electron energies above 40 keV. Recently, major technical developments have been realized and new equipment has been acquired which has allowed these limitations to be overcome and made feasible electron emission channeling experiments with short-lived isotopes and at low electron energies.\\\\ As first application, making use of two new on-line emission channeling setups at ISOLDE, we propose to investigate the lattice location of the transition metals Ni (2.5 h) and Co (1.6 h) in semiconductors, in particular in ZnO and GaN, by means of on-line $\\beta^{-}$-emission channeling experiments. In addition, we would like to study the lat...

  12. Photoluminescence emission from Alq3 organic layer in metal–Alq3–metal plasmonic structure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohr-Ran; Liao, Chung-Chi [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Fan, Wan-Ting [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China); Wu, Jin-Han; Chen, Cheng-Chang; Lin, Yi-Ping; Li, Jung-Yu; Chen, Shih-Pu [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute (ITRI), 195, Sec. 4, Chung-Hsin Road, Chutung 310, Taiwan (China); Ke, Wen-Cheng [Department of Mechanical Engineering, Yuan Ze University, Tao-Yuan 320, Taiwan (China); Chen, Nai-Chuan, E-mail: ncchen001@mail.cgu.edu.tw [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2014-06-01

    The emission properties of an organic layer embedded in a metal–organic–metal (MOM) structure were investigated. A partially radiative odd-SPW as well as a non-radiative even-SPW modes are supported by hybridization of the SPW modes on the opposite organic/metal interface in the structure. Because of the competition by this radiative SPW, the population of excitons that recombine to form non-radiative SPW should be reduced. This may account for why the photoluminescence intensity of the MOM sample is higher than that of an organic–metal sample even though the MOM sample has an additional metal layer that should intuitively act as a filter.

  13. On the origin of excimer emission in electroluminescence and photoluminescence spectra of polyfluorenes

    International Nuclear Information System (INIS)

    Vacha, Martin; Ha, Jaekook; Sato, Hisaya

    2007-01-01

    We report a study on the differences in red-shifted excimer band in photoluminescence (PL) and electroluminescence (EL) spectra of thin films of a copolymer of dibutylfluorene and butylphenylphenoxazine. The relative intensity of the excimer band in PL spectra increases with temperature above the polymer glass transition, and with the intensity of the excitation light. In EL spectra, on the other hand, the relative excimer intensity is seen to decrease with increasing driving voltage. These opposite trends originate from the different nature of excitations in PL and EL spectra: photoexcitation directly creates singlet excitons while electric excitation proceeds via interaction of injected electrons and holes. In case of electric excitation, the observed results might be due to trap-assisted excimer formation

  14. Time resolved photoluminescence studies of long lived emissive specie in F8BT:PFB blends

    Science.gov (United States)

    Gélinas, Simon; Howard, Ian; Friend, Richard; Silva, Carlos

    2009-03-01

    Type-II heterojunctions play a crucial role in organic optoelectronic devices. We use donor-acceptor polyfluorene blends as a model system to understand excited-state dynamics at heterojunctions. These interfacial excitations are intrachain singlet and triplet excitons, geminate polaron pairs, and exciplexes (interfacial charge-transfer excitons). Time-resolved photoluminescence (PL) spectra were taken at 10,and room temperature to investigate the interconversion dynamics of these species. We observe delayed PL with sub-linear excitation fluence dependence. This implies that delayed singlet exciton generation involves a bimolecular annihilation mechanism. By means of kinetic modeling, we propose triplet-triplet exciton annihilation as a regeneration route to singlet excitons, and subsequently to exciplexes. This points to a significant (<15,%) yield of triplet excitons after interfacial charge separation, and to the central role of these species on the interfacial dynamics.

  15. Intense, stable and excitation wavelength-independent photoluminescence emission in the blue-violet region from phosphorene quantum dots

    Science.gov (United States)

    Ge, Shuaipeng; Zhang, Lisheng; Wang, Peijie; Fang, Yan

    2016-01-01

    Nanoscale phosphorene quantum dots (PQDs) with few-layer structures were fabricated by pulsed laser ablation of a bulk black phosphorus target in diethyl ether. An intense and stable photoluminescence (PL) emission of the PQDs in the blue-violet wavelength region is clearly observed for the first time, which is attributed to electronic transitions from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) and occupied molecular orbitals below the HOMO (H-1, H-2), respectively. Surprisingly, the PL emission peak positions of the PQDs are not red-shifted with progressively longer excitation wavelengths, which is in contrast to the cases of graphene and molybdenum disulphide quantum dots. This excitation wavelength-independence is derived from the saturated passivation on the periphery and surfaces of the PQDs by large numbers of electron-donating functional groups which cause the electron density on the PQDs to be dramatically increased and the band gap to be insensitive to the quantum size effect in the PQDs. This work suggests that PQDs with intense, stable and excitation wavelength-independent PL emission in the blue-violet region have a potential application as semiconductor-based blue-violet light irradiation sources. PMID:27265198

  16. White photoluminescence emission from ZrO_2 co-doped with Eu"3"+, Tb"3"+ and Tm"3"+

    International Nuclear Information System (INIS)

    Lovisa, L.X.; Araújo, V.D.; Tranquilin, R.L.; Longo, E.; Li, M.S.; Paskocimas, C.A.; Bomio, M.R.D.; Motta, F.V.

    2016-01-01

    The search for high efficiency, reliable, low power consumption and environmental friendly materials for white light-emitting diodes has become a proficient field. Single-phase doped materials have been made to solve some of these challenges. Particles with color-tunable emission can be obtained by a combination of some lanthanide ions in the host material. The luminescence properties and crystalline structure of ZrO_2 particles co-doped with rare earth ions (RE"3"+ = Tb"3"+, Eu"3"+ and Tm"3"+) calcined at different temperatures were studied. We aimed to investigate the emission spectrum of the particles in the red, green, and blue regions under UV excitation. The x and y coordination chromaticity - (x = 0.34, y = 0.34) and (x = 0.31, y = 0.34) - presented values close to those of the white color (x = y = 0.33). In conclusion, the ZrO_2:RE"3"+ powers were successfully obtained by the complex polymerization method and are promising candidates for white light-emitting applications. - Highlights: The ZrO_2:RE materials presented here are promising photoluminescent materials. The CIE coordinates calculated are disposed in the blank region in the CIE diagram. The results for the Raman confirm the response obtained by XRD: stabilization of cubic phase.

  17. Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Santilli do Nascimento Libanori, Gabriela [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Avansi Jr, Waldir [Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Arnold Schimidt, 13566-590 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN/LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, R. Francisco Degni, 55, Bairro Quitandinha, 14801-907 Araraquara, SP (Brazil)

    2015-09-15

    For this research, we studied the influence of titanium tetrachloride (TC) and titanium tetraisopropoxide (TTP) precursors on CaTiO{sub 3} (CTO) synthesis by employing a microwave-assisted hydrothermal (MAH) method regarding their respective short-, medium- and long-range features to determine if the use of different titanium precursors enhances the structural evolution of the material. The growth mechanism for the formation of the micro-cube-shaped CTO is proposed to obtain nanoparticle aggregation of self-assembly nanoplates. The disorder coupled to the oxygen vacancies of [TiO{sub 5}]–[TiO{sub 6}] in complex clusters in the CTO 1 powder and twists in bonding between the [TiO{sub 6}]–[TiO{sub 6}] complex clusters in the CTO 2 powder were mainly responsible for photoluminescent (PL) emission. - Highlights: • Different titanium precursors enhance the structural evolution of the material. • [TiO{sub 5}]–[TiO{sub 6}] and twists in bonding [TiO{sub 6}]–[TiO{sub 6}] were responsible for PL emission. • Micro-cube shaped was formed by nanoparticle aggregation of self-assembly nanoplates.

  18. Blue emission in photoluminescence spectra of the red phosphor CaAlSiN3:Eu2+ at low Eu2+ concentration

    Science.gov (United States)

    Suda, Yoriko; Kamigaki, Yoshiaki; Yamamoto, Hajime

    2018-04-01

    In red phosphor CaAlSiN3:Eu2+, unintentional blue emission occurs with increasing intensity at low Eu2+ concentrations and also at low measurement temperatures. Time-resolved photoluminescence measurements were used to confirm the decrease in red emission and increase in blue emission with the decreasing Eu2+ concentration. The peak timing of blue emission occurred faster than that of red emission, and long lasting luminescence of red emission was observed as well as that of blue emission. The Eu2+ concentration dependences of the red and blue emissions were similar to those of the g values 4.75 (Eu2+) and 2.0025 (nitrogen vacancies), respectively, which were observed from electron spin resonance (ESR) measurements. The origin of the blue emission is proposed to be nitrogen vacancy defects, which had about the same ESR signal intensity as that of Eu2+ ions in CaAlSiN3:Eu2+ containing 0.01 at. % Eu2+. The possibility of red emission also arising from excited electron tunneling or thermal pathways via nitrogen vacancies is discussed. Long lasting red emission was observed, which is proposed to involve trapped electrons remaining at nitrogen vacancies, yielding blue emission and inducing red emission from Eu2+ ions.

  19. Negative thermal quenching of photoluminescence in ZnO

    International Nuclear Information System (INIS)

    Watanabe, M.; Sakai, M.; Shibata, H.; Satou, C.; Satou, S.; Shibayama, T.; Tampo, H.; Yamada, A.; Matsubara, K.; Sakurai, K.; Ishizuka, S.; Niki, S.; Maeda, K.; Niikura, I.

    2006-01-01

    We have studied photoluminescence (PL) spectra of ZnO single crystals at photon energies ranging between 2.1 and 3.4eV as a function of temperature to determine thermal quenching behavior in PL emission intensity. It appears that the deep level emissions, donor-acceptor pair emissions, and the bound excitonic emissions undergo negative thermal quenching (NTQ) at intermediate temperatures above ∼10K. By employing an NTQ formula expressed analytically as a function of temperature, we have obtained quantitative NTQ characteristics in terms of the activation energies associated with the intermediate states as well as nonradiative channels

  20. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.H. [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Velazquez-Salazar, J.J. [Department of Physics and Astronomy, The University of Texas at San Antonio One UTSA Circle, San Antonio TX 78249 (United States)

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  1. Longer than 1.9 μm photoluminescence emission from InAs quantum structure on GaAs (001) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ke; Ma, Wenquan, E-mail: wqma@semi.ac.cn; Huang, Jianliang; Zhang, Yanhua; Cao, Yulian; Huang, Wenjun; Luo, Shuai; Yang, Tao [Institute of Semiconductors, Chinese Academy of Sciences, Qinghua East Road A 35, Beijing 100083 (China)

    2015-07-27

    We report on photoluminescence (PL) emission with long wavelength for quantum structure by the sub-monolayer (SML) growth technique on GaAs (001) substrate. It is found that the PL emission wavelength can be controlled by controlling the SML InAs deposition amount. At 12 K, the PL peak position of the grown samples changes from about 1.66 to 1.78 μm. At 120 K, the PL emission of a sample reaches 1.91 μm. The physical mechanism responsible for the measured long wavelength PL emission may be related to strong In segregation and intermixing effects occurred in the structure grown by SML growth technique.

  2. UV and visible photoluminescence emission intensity of undoped and In-doped ZnO thin film and photoresponsivity of ZnO:In/Si hetero-junction

    Energy Technology Data Exchange (ETDEWEB)

    Zebbar, N., E-mail: nacbar2003@yahoo.fr [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Chabane, L. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Gabouze, N. [CRTSE, 02 Bd. Frantz Fanon, BP 140, Algiers (Algeria); Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32, El-Alia, Algiers (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32, El-Alia, Algiers (Algeria); Aida, M.S. [LCM et Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Belhousse, S. [CRTSE, 02 Bd. Frantz Fanon, BP 140, Algiers (Algeria); Hadj Larbi, F. [MEMS & Sensors, Division Microélectronique et Nanotechnologie, Centre de Développement des Technologies Avancées (CDTA), BP 17, Baba Hassen, Algiers (Algeria)

    2016-04-30

    Undoped zinc oxide (ZnO) and indium-doped (ZnO:In) thin films were grown at different temperatures (250–400 °C) on alkali-free borosilicate glass and n-Si (100) substrates by Ultrasonic Spray Pyrolysis method. The structural, compositional, optical and electrical properties of ZnO films were investigated by X-ray diffraction, Scanning Electron Microscopy, Rutherford Back Scattering Spectroscopy, Fourier Transform Infrared spectroscopy, photoluminescence (PL) and the four-point probe technique. The predominance of ultraviolet (UV) and blue emission intensities was found to be closely dependent on the resistivity of the film. The visible emission band (peaking at 432 nm) prevails for low film resistivity, ranging from 10{sup −2} to 1 Ω·cm. By contrast, for higher resistivity (> 1 Ω·cm), there is a predominance of the UV band (382 nm). The PL and photoresponsivity results of fabricated ZnO:In/n-Si(100) heterojunctions prepared at different temperatures are discussed. The maximum spectral response of the ZnO:8%In/Si heterojunction diode fabricated at 250 °C was about 80 mA/W at zero bias. The highlighted results are attractive for the optoelectronic applications. - Highlights: • Properties of ZnO thin films grown by Ultrasonic Spray Pyrolysis at 350 °C. • Photoluminescence emission intensity in undoped ZnO film: effect of the resistivity • Photoluminescence emission intensity of In-doped ZnO film is resistivity dependent. • The spectral response of ZnO:In/Si hetero-junction deposited in the range (250–400 °C)

  3. UV and visible photoluminescence emission intensity of undoped and In-doped ZnO thin film and photoresponsivity of ZnO:In/Si hetero-junction

    International Nuclear Information System (INIS)

    Zebbar, N.; Chabane, L.; Gabouze, N.; Kechouane, M.; Trari, M.; Aida, M.S.; Belhousse, S.; Hadj Larbi, F.

    2016-01-01

    Undoped zinc oxide (ZnO) and indium-doped (ZnO:In) thin films were grown at different temperatures (250–400 °C) on alkali-free borosilicate glass and n-Si (100) substrates by Ultrasonic Spray Pyrolysis method. The structural, compositional, optical and electrical properties of ZnO films were investigated by X-ray diffraction, Scanning Electron Microscopy, Rutherford Back Scattering Spectroscopy, Fourier Transform Infrared spectroscopy, photoluminescence (PL) and the four-point probe technique. The predominance of ultraviolet (UV) and blue emission intensities was found to be closely dependent on the resistivity of the film. The visible emission band (peaking at 432 nm) prevails for low film resistivity, ranging from 10 −2 to 1 Ω·cm. By contrast, for higher resistivity (> 1 Ω·cm), there is a predominance of the UV band (382 nm). The PL and photoresponsivity results of fabricated ZnO:In/n-Si(100) heterojunctions prepared at different temperatures are discussed. The maximum spectral response of the ZnO:8%In/Si heterojunction diode fabricated at 250 °C was about 80 mA/W at zero bias. The highlighted results are attractive for the optoelectronic applications. - Highlights: • Properties of ZnO thin films grown by Ultrasonic Spray Pyrolysis at 350 °C. • Photoluminescence emission intensity in undoped ZnO film: effect of the resistivity • Photoluminescence emission intensity of In-doped ZnO film is resistivity dependent. • The spectral response of ZnO:In/Si hetero-junction deposited in the range (250–400 °C)

  4. Influence of Cu substitution on the structural ordering, photocatalytic activity and photoluminescence emission of Ag3-2xCuxPO4 powders

    Science.gov (United States)

    Pereira, Wyllamanney da S.; Sczancoski, Júlio C.; Calderon, Yormary N. C.; Mastelaro, Valmor R.; Botelho, Gleice; Machado, Thales R.; Leite, Edson R.; Longo, Elson

    2018-05-01

    Materials presenting high photocatalytic performance and interesting photoluminescence emissions are promising candidates for photodegradation of organic pollutants discharged into natural waters as well as for development of new electro-optical devices, respectively. In this study, Ag3-2xCuxPO4 (x = 0.00, 0.01, 0.02, 0.04 and 0.08) powders were synthesized by the precipitation method. The long- and short-range structural ordering was affected when the copper (Cu) content was increased in the lattice, as identified by X-ray diffraction patterns, Fourier transform infrared spectroscopy and Raman spectroscopy, respectively. The field emission scanning electron microscope and transmission electron microscope revealed a particle system composed of irregular spherical-like microcrystals. The presence of Cu as well as its real amount in the samples were confirmed by means of X-ray photoelectron spectroscopy and inductively coupled plasma-atomic emission spectrometry, respectively. On increasing Cu level, a slight variation was noted on the photocatalytic activity of Ag3-2xCuxPO4 powders for degradation of rhodamine B under visible light irradiation. A photodegradation mechanism was proposed in details. The photoluminescence emissions were explained by electronic transitions involving intermediary energy levels in the band gap. The origin these energy levels was related to defects caused by the substitution of Ag by Cu in the crystalline structure.

  5. ZnO nanorod arrays prepared by chemical bath deposition combined with rapid thermal annealing: structural, photoluminescence and field emission characteristics

    International Nuclear Information System (INIS)

    Chen, Hung-Wei; He, Hsin-Min; Lee, Yi-Mu; Yang, Hsi-Wen

    2016-01-01

    ZnO nanorod arrays were prepared by low temperature chemical bath deposition (CBD) combined with rapid thermal annealing (RTA) under different ambient conditions. The structure and morphology of the synthesized ZnO have been characterized by field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The obtained ZnO samples are highly crystalline with a hexagonal wurtzite phase and also display well-aligned array structure. A pronounced effect on increased nanorod length was found for the RTA-treated ZnO as compared to the as-grown ZnO. Analysis of XRD indicates that the (0 0 2) feature peak of the as-grown ZnO was shifted towards a lower angle as compared to the peaks of RTA-treated ZnO samples due to the reduction of tensile strain along the c-axis by RTA. Photoluminescence (PL) studies reveal that the ZnO nanorod arrays receiving RTA in an O 2 environment have the sharpest UV emission band and greatest intensity ratio of near band-edge emission (NBE) to deep level emission (DLE). Additionally, the effects of RTA on the field emission properties were evaluated. The results demonstrate that RTA an O 2 environment can lower the turn-on field and improve the field enhancement factor. The stability of the field emission current was also tested for 4 h. (paper)

  6. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina

    2014-04-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  7. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina; Bourlinos, Athanasios B.; Kozak, Ondrej; Berka, Karel; Siskova, Karolina M.; Havrdova, Marketa; Tucek, Jiri; Safarova, Klara; Otyepka, Michal; Giannelis, Emmanuel P.; Zboril, Radek

    2014-01-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  8. Photoluminescence of Diamondoid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Clay, William; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /Stanford U., Geballe Lab.; Sasagawa, Takao; Iwasa, Akio; /TIT, Nagatsuta; Liu, Zhi; /LBNL, ALS; Dahl, Jeremy E.; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /Stanford U., Geballe Lab.; Carlson, Robert M.K.; /Molecular Diamond Technologies, Chevron Technology Ventures; Kelly, Michael; Melos, Nicholas; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /Stanford U., Geballe Lab.; Shen, Zhi-Xun; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /Stanford U., Geballe Lab. /SIMES, Stanford

    2012-04-03

    The photoluminescence of diamondoids in the solid state is examined. All of the diamondoids are found to photoluminesce readily with initial excitation wavelengths ranging from 233 nm to 240 nm (5.3 eV). These excitation energies are more than 1 eV lower than any previously studied saturated hydrocarbon material. The emission is found to be heavily shifted from the absorption, with emission wavelengths of roughly 295 nm (4.2 eV) in all cases. In the dissolved state, however, no uorescence is observed for excitation wavelengths as short as 200 nm. We also discuss predictions and measurements of the quantum yield. Our predictions indicate that the maximum yield may be as high as 25%. Our measurement of one species, diamantane, gives a yield of 11%, the highest ever reported for a saturated hydrocarbon, even though it was likely not at the optimal excitation wavelength.

  9. A facile synthesis of graphene oxide–ZnS/ZnO nanocomposites and observations of thermal quenching of visible photoluminescence emission and nonlinear optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Kole, A.K.; Biswas, S. [Nanoscience Laboratory, Dept. of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India); Tiwary, C.S. [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Kumbhakar, P., E-mail: pathik.kumbhakar@phy.nitdgp.ac.in [Nanoscience Laboratory, Dept. of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India)

    2016-11-15

    Here we have reported a facile synthesis of graphene oxide–ZnS/ZnO nanocomposite and the temperature dependent photoluminescence (PL) emissions in the synthesized materials, which are scarcely been available in the literature. In the present work PL emission in GO and its composites with ZnS and ZnO semiconductor quantum dots (QDs) have been measured at variable temperatures in 283–353 K temperature region. From the measured results it has been found that quenching of PL emission has been taken place in the composite sample and it has been proposed that as the temperature is increased, the excited electrons in the localized states formed by the sp{sup 2} clusters in GO can migrate to the nearby sp{sup 3} defects states, thereby the intensity of PL emission is reduced. Nonlinear Optical (NLO) properties as well as the optical limiting (OL) properties has also been studied by using an indigenously developed Z-scan technique with a 10 ns laser pulse at 1064 nm laser radiation. Two photon absorptions (2PA) behavior have been found to be the dominant mechanism in the synthesized samples. A suitable energy level scheme has been proposed to explain the observed PL emission behavior as well as the 2PA mechanism. The present report will open up a lot of prospects for synthesizing GO-semiconductor nanocomposites with semiconductor materials as well as for potential applications in future luminescent devices.

  10. Methane emissions from sugarcane vinasse storage and transportation systems: Comparison between open channels and tanks

    Science.gov (United States)

    Oliveira, Bruna Gonçalves; Carvalho, João Luís Nunes; Chagas, Mateus Ferreira; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente; Feigl, Brigitte Josefine

    2017-06-01

    Over the last few years the brazilian sugarcane sector has produced an average of 23.5 million liters of ethanol annually. This scale of production generates large amounts of vinasse, which depending on the manner that is disposed, can result significant greenhouse gas emissions. This study aimed to quantify the methane (CH4) emissions associated with the two most widespread systems of vinasse storage and transportation used in Brazil; open channel and those comprising of tanks and pipes. Additionally, a laboratory incubation study was performed with the aim of isolating the effects of vinasse, sediment and the interaction between these factors on CH4 emissions. We observed significant differences in CH4 emissions between the sampling points along the channels during both years of evaluation (2012-2013). In the channel system, around 80% of CH4 emissions were recorded from uncoated sections. Overall, the average CH4 emission intensity was 1.36 kg CO2eq m-3 of vinasse transported in open channels, which was 620 times higher than vinasse transported through a system of tanks and closed pipes. The laboratory incubation corroborated field results, suggesting that vinasse alone does not contribute significant emissions of CH4. Higher CH4 emissions were observed when vinasse and sediment were incubated together. In summary, our findings demonstrate that CH4 emissions originate through the anaerobic decomposition of organic material deposited on the bottom of channels and tanks. The adoption of coated channels as a substitute to uncoated channels offers the potential for an effective and affordable means of reducing CH4 emissions. Ultimately, the modernization of vinasse storage and transportation systems through the adoption of tank and closed pipe systems will provide an effective strategy for mitigating CH4 emissions generated during the disposal phase of the sugarcane ethanol production process.

  11. Red-shift of the photoluminescent emission peaks of CdTe quantum dots due to the synergistic interaction with carbon quantum dot mixtures

    International Nuclear Information System (INIS)

    Pelayo, E; Zazueta, A; López-Delgado, R; Ayón, A; Saucedo, E; Ruelas, R

    2016-01-01

    We report the relatively large red-shift effect observed in down-shifting carbon quantum dots (CQDs) that is anticipated to have a positive impact on the power conversion efficiency of solar cells. Specifically, with an excitation wavelength of 390 nm, CQDs of different sizes, exhibited down-shifted emission peaks centered around 425 nm. However, a solution comprised of a mixture of CQDs of different sizes, was observed to have an emission peak red-shifted to 515 nm. The effect could arise when larger carbon quantum dots capture the photons emitted by their smaller counterparts followed by the subsequent re-emission at longer wavelengths. Furthermore, the red-shift effect was also observed in CdTe QDs when added to a solution with the aforementioned mixture of Carbon QDs. Thus, whereas a solution solely comprised of a collection of CdTe QDs of different sizes, exhibited a down-shifted photoluminescence centered around 555 nm, the peak was observed to be further red-shifted to 580 nm when combined with the solution of CQDs of different sizes. The quantum dot characterization included crystal structure analysis as well as photon absorption and photoluminescence wavelengths. Subsequently, the synthesized QDs were dispersed in a polymeric layer of poly-methyl-methacrylate (PMMA) and incorporated on functional and previously characterized solar cells, to quantify their influence in the electrical performance of the photovoltaic structures. We discuss the synthesis and characterization of the produced Carbon and CdTe QDs, as well as the observed improvement in the power conversion efficiency of the fabricated photovoltaic devices. (paper)

  12. Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

    Energy Technology Data Exchange (ETDEWEB)

    Diroll, Benjamin T.; Talapin, Dmitri V.; Schaller, Richard D.

    2017-02-13

    Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS and newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields of 2% or less for single excitons, which we show results from hole trapping, the samples exhibit low ASE thresholds. Furthermore, four-monolayer CdS samples show ASE at shorter wavelengths than any reported film of colloidal quantum-confined material. This work underlines that low quantum yields for single excitons do not necessarily lead to a poor gain medium. The low ASE thresholds originate from negligible dispersion in thickness, large absorption cross sections of 2.8 × 10–14 cm–2, and rather slow (150 to 300 ps) biexciton recombination. We show that under higher-fluence excitation, ASE can kinetically outcompete hole trapping. Using nanoplatelets as the gain medium, lasing is observed in a linear optical cavity. This work confirms the fundamental advantages of colloidal quantum well structures as gain media, even in the absence of high photoluminescence efficiency.

  13. Strong violet-blue light photoluminescence emission at room temperature in SrZrO3: Joint experimental and theoretical study

    International Nuclear Information System (INIS)

    Longo, V.M.; Cavalcante, L.S.; Erlo, R.; Mastelaro, V.R.; Figueiredo, A.T. de; Sambrano, J.R.; Lazaro, S. de; Freitas, A.Z.; Gomes, L.; Vieira, N.D.; Varela, J.A.; Longo, Elson

    2008-01-01

    Ultrafine ordered and disordered SrZrO 3 powders were prepared by the polymeric precursor method. The structural evolution from structural disorder to order was monitored by X-ray diffraction and X-ray absorption near-edge spectroscopy. Complex cluster vacancies [ZrO 5 .V O Z ]and[SrO 11 .V O Z ] (where V O Z =V O X , V O · andV O ·· ) were proposed for disordered powders. The intense violet-blue light photoluminescence emission measured at room temperature in the disordered powders was attributed to complex cluster vacancies. High-level quantum mechanical calculations within the density functional theory framework were used to interpret the experimental results

  14. Secondary electron emission induced by channeled relativistic electrons in a (1 1 0) Si crystal

    International Nuclear Information System (INIS)

    Korotchenko, K.B.; Kunashenko, Yu P.; Tukhfatullin, T.A.

    2012-01-01

    A new effect that accompanies electrons channeled in a crystal is considered. This phenomenon was previously predicted was called channeling secondary electron emission (CSEE). The exact CSEE cross-section on the basis of using the exact Bloch wave function of electron channeled in a crystal is obtained. The detailed investigation of CSEE cross-section is performed. It is shown that angular distribution of electrons emitted due to CSEE has a complex form.

  15. Photoluminescence light-up detection of zinc ion and imaging in living cells based on the aggregation induced emission enhancement of glutathione-capped copper nanoclusters.

    Science.gov (United States)

    Lin, Liyun; Hu, Yuefang; Zhang, Liangliang; Huang, Yong; Zhao, Shulin

    2017-08-15

    In this work, we prepared glutathione (GSH)-capped copper nanoclusters (Cu NCs) with red emission by simply adjusting the pH of GSH/Cu 2+ mixture at room temperature. A photoluminescence light-up method for detecting Zn 2+ was then developed based on the aggregation induced emission enhancement of GSH-capped Cu NCs. Zn 2+ could trigger the aggregation of Cu NCs, inducing the enhancement of luminescence and the increase of absolute quantum yield from 1.3% to 6.2%. GSH-capped Cu NCs and the formed aggregates were characterized, and the possible mechanism was also discussed. The prepared GSH-capped Cu NCs exhibited a fast response towards Zn 2+ and a wider detection range from 4.68 to 2240μM. The detection limit (1.17μM) is much lower than that of the World Health Organization permitted in drinking water. Furthermore, taking advantages of the low cytotoxicity, large Stokes shift, red emission and light-up detection mode, we explored the use of the prepared GSH-capped Cu NCs in the imaging of Zn 2+ in living cells. The developed luminescence light-up nanoprobe may hold the potentials for Zn 2+ -related drinking water safety and biological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. (n,p) emission channeling measurements on ion-implanted beryllium

    CERN Multimedia

    Jakubek, J; Uher, J

    2007-01-01

    We propose to perform emission-channeling measurements using thermal neutron induced proton emission from ion-implanted $^{7}$Be. The physics questions addressed concern the beryllium doping of III-V and II-VI semiconductors and the host dependence of the electron capture half-life of $^{7}$Be.

  17. Synthesis and photoluminescence enhancement of PVA capped Mn2+ doped ZnS nanoparticles and observation of tunable dual emission: A new approach

    International Nuclear Information System (INIS)

    Viswanath, R.; Bhojya Naik, H.S.; Yashavanth Kumar, G.S.; Prashanth Kumar, P.N.; Harish, K.N.; Prabhakara, M.C.; Praveen, R.

    2014-01-01

    Highlights: • Synthesis of PVA capped Mn 2+ doped ZnS nanoparticles by chemical precipitation method in air atmosphere. • Characterized by the spectral techniques. • Study on their optical properties. • Calculation of particle size by different techniques. • Investigation of the increased luminescence characteristics (UV to IR region) of Mn 2+ doped ZnS ions at room temperature and the origin of the luminescence observed. - Abstract: This paper reports the enhanced photoluminescence (PL) property of polyvinyl alcohol (PVA) capped Mn 2+ doped ZnS nanocrystals prepared by chemical precipitation method. The surface-modified Mn 2+ doped ZnS nanocrystals resulted in the multi-color property. The morphology and crystallite size were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The crystallite size was estimated to be 5 nm from HRTEM and calculated as 2–4 nm from peak broadening of the X-ray diffraction (XRD) pattern with cubic zincblende structure. Increase in the band gap with decrease in the crystallite size was observed from the UV–visible absorption spectrum, which confirms the quantum confinement effect. The room temperature photoluminescence (PL) emission measurements revealed the presence of blue (427 nm) and near IR reddish–orange (752 nm) emission bands in addition to the typical yellow–orange (585 nm) bands in all the Mn 2+ doped samples, which were attributed due to transition within the 3ds configuration of Mn 2+ ions incorporation in ZnS host under UV excitation at 320 nm. As far as we know, the reddish–orange bands at 752 nm near IR region along with the blue and yellow–orange colored PL are reported for the first time. In this way, the PL color from these ZnS nanocrystals can be tuned from UV to near infrared region (IR). The synthesized ZnS:Mn NPs can be further functionalized for using them as biolabels

  18. Synthesis and photoluminescence enhancement of PVA capped Mn{sup 2+} doped ZnS nanoparticles and observation of tunable dual emission: A new approach

    Energy Technology Data Exchange (ETDEWEB)

    Viswanath, R. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Bhojya Naik, H.S., E-mail: hsb_naik@rediffmail.com [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Yashavanth Kumar, G.S.; Prashanth Kumar, P.N.; Harish, K.N. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, 577451 (India); Prabhakara, M.C. [Department of P.G. Studies and Research in Industrial Chemistry, Sir. M.V. Government Science College, Bommanakatte, Shimoga, Bhadravathi, Karnataka, 577302 (India); Praveen, R. [Department of Technical Education, Automobile Technology Branch HMS Polytechnic (Government Aided), Tumkur, Karnataka, 572102 (India)

    2014-05-01

    Highlights: • Synthesis of PVA capped Mn{sup 2+} doped ZnS nanoparticles by chemical precipitation method in air atmosphere. • Characterized by the spectral techniques. • Study on their optical properties. • Calculation of particle size by different techniques. • Investigation of the increased luminescence characteristics (UV to IR region) of Mn{sup 2+} doped ZnS ions at room temperature and the origin of the luminescence observed. - Abstract: This paper reports the enhanced photoluminescence (PL) property of polyvinyl alcohol (PVA) capped Mn{sup 2+} doped ZnS nanocrystals prepared by chemical precipitation method. The surface-modified Mn{sup 2+} doped ZnS nanocrystals resulted in the multi-color property. The morphology and crystallite size were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The crystallite size was estimated to be 5 nm from HRTEM and calculated as 2–4 nm from peak broadening of the X-ray diffraction (XRD) pattern with cubic zincblende structure. Increase in the band gap with decrease in the crystallite size was observed from the UV–visible absorption spectrum, which confirms the quantum confinement effect. The room temperature photoluminescence (PL) emission measurements revealed the presence of blue (427 nm) and near IR reddish–orange (752 nm) emission bands in addition to the typical yellow–orange (585 nm) bands in all the Mn{sup 2+} doped samples, which were attributed due to transition within the 3ds configuration of Mn{sup 2+} ions incorporation in ZnS host under UV excitation at 320 nm. As far as we know, the reddish–orange bands at 752 nm near IR region along with the blue and yellow–orange colored PL are reported for the first time. In this way, the PL color from these ZnS nanocrystals can be tuned from UV to near infrared region (IR). The synthesized ZnS:Mn NPs can be further functionalized for

  19. Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In2O3 nanowires

    Science.gov (United States)

    Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P.; Schaller, Richard D.; Gosztola, David J.; Stroscio, Michael A.; Dutta, Mitra

    2018-04-01

    We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In2O3) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In2O3 nanostructure based device characteristics for potential optoelectronic applications. In2O3 nanowires with cubic crystal structure (c-In2O3) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor-liquid-solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy ({V}{{O}}) defects as confirmed using Raman spectroscopy. A combination of high resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of {V}{{O}} defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.

  20. White photoluminescence emission from ZrO{sub 2} co-doped with Eu{sup 3+}, Tb{sup 3+} and Tm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Lovisa, L.X., E-mail: lovisaengmat@ig.com.br [Departamento de Engenharia de Materiais, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Araújo, V.D. [UACSA, Universidade Federal Rural de Pernambuco, 54510-000, Cabo de Santo Agostinho, PE (Brazil); Tranquilin, R.L.; Longo, E. [LIEC, Universidade Federal de São Carlos, 13565-905, São Carlos, SP (Brazil); Li, M.S. [Instituto de Física de São Carlos, Universidade de São Paulo, 13566-590, São Carlos, SP (Brazil); Paskocimas, C.A.; Bomio, M.R.D.; Motta, F.V. [Departamento de Engenharia de Materiais, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil)

    2016-07-25

    The search for high efficiency, reliable, low power consumption and environmental friendly materials for white light-emitting diodes has become a proficient field. Single-phase doped materials have been made to solve some of these challenges. Particles with color-tunable emission can be obtained by a combination of some lanthanide ions in the host material. The luminescence properties and crystalline structure of ZrO{sub 2} particles co-doped with rare earth ions (RE{sup 3+} = Tb{sup 3+}, Eu{sup 3+} and Tm{sup 3+}) calcined at different temperatures were studied. We aimed to investigate the emission spectrum of the particles in the red, green, and blue regions under UV excitation. The x and y coordination chromaticity - (x = 0.34, y = 0.34) and (x = 0.31, y = 0.34) - presented values close to those of the white color (x = y = 0.33). In conclusion, the ZrO{sub 2}:RE{sup 3+} powers were successfully obtained by the complex polymerization method and are promising candidates for white light-emitting applications. - Highlights: The ZrO{sub 2}:RE materials presented here are promising photoluminescent materials. The CIE coordinates calculated are disposed in the blank region in the CIE diagram. The results for the Raman confirm the response obtained by XRD: stabilization of cubic phase.

  1. Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In 2 O 3 nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P.; Schaller, Richard D.; Gosztola, David J.; Stroscio, Michael A.; Dutta, Mitra

    2018-03-01

    We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In2O3) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In2O3 nanostructure based device characteristics for potential optoelectronic applications. In2O3 nanowires with cubic crystal structure (c-In2O3) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor–liquid–solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy (VO) defects as confirmed using Raman spectroscopy. A combination of high resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of VO defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.

  2. Photoluminescence decay kinetics of doped ZnS nanophosphors

    International Nuclear Information System (INIS)

    Sharma, Rajesh; Bhatti, H S

    2007-01-01

    Doped nanophosphor samples of ZnS:Mn, ZnS:Mn, Co and ZnS:Mn, Fe were prepared using a chemical precipitation method. Photoluminescence (PL) spectra were obtained and lifetime studies of the nanophosphors were carried out at room temperature. To the best of our knowledge, there are very few reports on the photoluminescence investigations of Co-doped or Fe-doped ZnS:Mn nanoparticles in the literature. Furthermore, there is no report on luminescence lifetime shortening of ZnS:Mn nanoparticles doped with Co or Fe impurity. Experimental results showed that there is considerable change in the photoluminescence spectra of ZnS:Mn nanoparticles doped with X (X = Co, Fe). The PL spectra of the ZnS:Mn, Co nanoparticle sample show three peaks at 410, 432 and 594 nm, while in the case of the ZnS:Mn, Fe nanoparticle sample the peaks are considerably different. The lifetimes are found to be in microsecond time domain for 594 nm emission, while nanosecond order lifetimes are obtained for 432 and 411 nm emission in ZnS:Mn, X nanophosphor samples. These lifetimes suggest a new additional decay channel of the carrier in the host material

  3. Tunable luminescent emission characterization of type-I and type-II systems in CdS-ZnSe core-shell nanoparticles: Raman and photoluminescence study.

    Science.gov (United States)

    Ca, Nguyen Xuan; Lien, V T K; Nghia, N X; Chi, T T K; Phan, The-Long

    2015-11-06

    We used wet chemical methods to synthesize core-shell nanocrystalline samples CdS(d)/ZnSe N , where d = 3-6 nm and N = 1-5 are the size of CdS cores and the number of monolayers grown on the cores, respectively. By annealing typical CdS(d)/ZnSe N samples (with d = 3 and 6 nm and N = 2) at 300 °C for various times t an = 10-600 min, we created an intermediate layer composed of Zn1-x Cd x Se and Cd1-x Zn x S alloys with various thicknesses. The formation of core-shell structures and intermediate layers was monitored by Raman scattering and UV-vis absorption spectrometers. Careful photoluminescence studies revealed that the as-prepared CdS(d)/ZnSe N samples with d = 5 nm and N = 2-4, and the annealed samples CdS(3 nm)/ZnSe2 with t an ≤ 60 min and CdS(6 nm)/ZnSe2 with t an ≤ 180 min, show the emission characteristics of type-II systems. Meanwhile, the other samples show the emission characteristics of type-I systems. These results prove that the partial separation of photoexcited carriers between the core and shell is dependent strongly on the engineered core-shell nanostructures, meaning the sizes of the core, shell, and intermediate layers. With the tunable luminescence properties, CdS-ZnSe-based core-shell materials are considered as promising candidates for multiple-exciton generation and single-photon sources.

  4. A 31-channel MR brain array coil compatible with positron emission tomography.

    Science.gov (United States)

    Sander, Christin Y; Keil, Boris; Chonde, Daniel B; Rosen, Bruce R; Catana, Ciprian; Wald, Lawrence L

    2015-06-01

    Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation. The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. © 2014 Wiley Periodicals, Inc.

  5. Emission Channeling Studies of the Lattice Site of Oversized Alkali Atoms Implanted in Metals

    CERN Multimedia

    2002-01-01

    % IS340 \\\\ \\\\ As alkali atoms have the largest atomic radius of all elements, the determination of their lattice configuration following implantation into metals forms a critical test for the various models predicting the lattice site of implanted impurity atoms. The site determination of these large atoms will especially be a crucial check for the most recent model that relates the substitutional fraction of oversized elements to their solution enthalpy. Recent exploratory $^{213}$Fr and $^{221}$Fr $\\alpha$-emission channeling experiments at ISOLDE-CERN and hyperfine interaction measurements on Fr implanted in Fe gave an indication for anomalously large substitutional fractions. To investigate further the behaviour of Fr and other alkali atoms like Cs and Rb thoroughly, more on-line emission channeling experiments are needed. We propose a number of shifts for each element, where the temperature of the implanted metals will be varied between 50$^\\circ$ and 700$^\\circ$~K. Temperature dependent measurements wi...

  6. Emission channeling studies of Indium Phosphide at low temperatures at CERN-ISOLDE

    CERN Document Server

    Amorim, Lígia Marina; Wahl, Ulrich

    $^{111}$In radioactive atoms were implanted into a single crystal of InP. After annealing for lattice recovery of implantation defects, the lattice site location of $^{111}$In/$^{111}$Cd was studied with the emission channeling technique, from room temperature ( 300K) down to 50K at CERN-ISOLDE. This work aims to test a recently developed cooling station for emission channeling experiments. InP is a material with a relatively low Debye temperature, where significant changes of atomic vibrations are expected with temperature, thus providing an ideal test ground of the effects, which can be expected to influence the data, i.e., de-channeling from lattice vibration and changes of the root mean square displacement (r.m.s.) of the atomic position of the probe atom. In the future we intend to apply these studies to monitor individual impurities or lattice constituents, with temperature, upon phase transitions as well as studying lattice sites of dopants implanted at low temperature.

  7. Structure, composition, morphology, photoluminescence and cathodoluminescence properties of ZnGeN{sub 2} and ZnGeN{sub 2}:Mn{sup 2+} for field emission displays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.-H. [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China); Guangzhou Research Institute of Non-ferrous Metals, Guangzhou, Guangdong 510651 (China); Wang, J., E-mail: ceswj@mail.sysu.edu.cn [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China); Yeh, C.-W.; Ke, W.-C.; Liu, R.-S. [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Tang, J.-K. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Xie, M.-B.; Liang, H.-B.; Su, Q. [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275 (China)

    2010-12-15

    Yellowish-orange-emitting ZnGeN{sub 2} and orange-red-emitting ZnGeN{sub 2}:Mn were synthesized by a facile and mild gas-reduction-nitridation reaction at 1153 K under NH{sub 3} flow with air-stable raw materials ZnO, GeO{sub 2} and MnCO{sub 3}. The structure, composition, morphology, photoluminescence and cathodoluminescence properties of ZnGeN{sub 2} doped with or without Mn{sup 2+} were systematically investigated. Rietveld refinements show that the as-synthesized samples are obtained as single-phase compounds and crystallize as an orthorhombic structure with a space group of Pna2{sub 1}. The actual chemical composition of the as-prepared ZnGeN{sub 2} determined by energy dispersive X-ray spectroscopy suggests that the Ge vacancy defects probably exist in the host. The SEM image reveals that the Zn{sub 0.99}Mn{sub 0.01}GeN{sub 2} particles form aggregates {approx}500-600 nm in size. The diffuse reflection spectrum and photoluminescence excitation spectrum confirm that the band edge absorption of ZnGeN{sub 2} at low energy is 3.3 eV ({approx}376 nm). Upon UV light excitation and electron beam excitation, ZnGeN{sub 2} gives an intense yellowish-orange emission around 580-600 nm, associated with a deep defect level due to the Ge vacancy defects, and ZnGeN{sub 2}:Mn shows an intense red emission at 610 nm due to the {sup 4}T{sub 1g}({sup 4}G) {yields} 6A{sub 1g}({sup 6}S) of Mn{sup 2+}. The unusual red emission of Mn{sup 2+} in tetrahedral Zn{sup 2+} sites is attributed to the strong nephelauxetic effect between Mn{sup 2+} and the surrounding tetrahedrally coordinated nitrogen. The photoluminescence and cathodoluminescence emission colors of ZnGeN{sub 2}:Mn have a high color purity of {approx}93-98%. These results demonstrate that ZnGeN{sub 2}:Mn is a novel, promising red-emitting nitride, potentially applicable to field emission displays with brilliant color-rendering properties and a large color gamut.

  8. Electronic band structure in porous silicon studied by photoluminescence and photoluminescence excitation spectroscopy

    International Nuclear Information System (INIS)

    Lee, Ki-Won; Kim, Young-You

    2004-01-01

    In this research, we used photoluminescence (PL) and photoluminescence excitation (PLE) to visualize the electronic band structure in porous silicon (PS). From the combined results of the PLE measurements at various PL emission energies and the PL measurements under excitation at various PLE absorption energies, we infer that three different electronic band structures, originating from different luminescent origins, give rise to the PL spectrum. Through either thermal activation or diffusive transfer, excited carriers are moved to each of the electronic band structures.

  9. Attribution of atmospheric sulfur dioxide over the English Channel to dimethyl sulfide and changing ship emissions

    Science.gov (United States)

    Yang, Mingxi; Bell, Thomas G.; Hopkins, Frances E.; Smyth, Timothy J.

    2016-04-01

    Atmospheric sulfur dioxide (SO2) was measured continuously from the Penlee Point Atmospheric Observatory (PPAO) near Plymouth, United Kingdom, between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near Plymouth Sound. A new International Maritime Organization (IMO) regulation came into force in January 2015 to reduce the maximum allowed sulfur content in ships' fuel 10-fold in sulfur emission control areas such as the English Channel. Our observations suggest a 3-fold reduction in ship-emitted SO2 from 2014 to 2015. Apparent fuel sulfur content calculated from coincidental SO2 and carbon dioxide (CO2) peaks from local ship plumes show a high level of compliance to the IMO regulation (> 95 %) in both years (˜ 70 % of ships in 2014 were already emitting at levels below the 2015 cap). Dimethyl sulfide (DMS) is an important source of atmospheric SO2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO2 burden over the English Channel increased from about one-third in 2014 to about one-half in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

  10. Low-temperature photoluminescence in chalcogenide glasses doped with rare-earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Kostka, Petr, E-mail: petr.kostka@irsm.cas.cz [Institute of Rock Structure and Mechanics AS CR, V Holešovičkách 41, 182 09 Praha 8 (Czech Republic); Zavadil, Jiří [Institute of Photonics and Electronics AS CR, Chaberská 57, 182 51 Praha 8, Kobylisy (Czech Republic); Iovu, Mihail S. [Institute of Applied Physics, Academy of Sciences of Moldova, Str. Academiei 5, MD-28 Chisinau, Republic of Moldova (Moldova, Republic of); Ivanova, Zoya G. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia (Bulgaria); Furniss, David; Seddon, Angela B. [Mid-Infrared Photonics Group, George Green Institute for Electromagnetics Research, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2015-11-05

    Sulfide and oxysulfide bulk glasses Ga-La-S-O, Ge-Ga-S and Ge-Ga-As-S doped, or co-doped, with various rare-earth (RE{sup 3+}) ions are investigated for their room temperature transmission and low-temperature photoluminescence. Photoluminescence spectra are collected by using external excitation into the Urbach tail of the fundamental absorption edge of the host-glass. The low-temperature photoluminescence spectra are dominated by the broad-band luminescence of the host glass, with superimposed relatively sharp emission bands due to radiative transitions within 4f shells of RE{sup 3+} ions. In addition, the dips in the host-glass luminescence due to 4f-4f up-transitions of RE{sup 3+} ions are observed in the Ge-Ga-S and Ge-Ga-As-S systems. These superimposed narrow effects provide a direct experimental evidence of energy transfer between the host glass and respective RE{sup 3+} dopants. - Highlights: • An evidence of energy transfer from host-glass to doped-in RE ions is presented. • Energy transfer is manifested by dips in host-glass broad-band luminescence. • This channel of energy transfer is documented on selected RE doped sulfide glasses. • Photoluminescence spectra are dominated by broad band host-glass luminescence. • Presence of RE ions is manifested by superimposed narrow 4f-4f transitions.

  11. Intercomparison of two BRDF models in the estimation of the directional emissivity in MIR channel from MSG1-SEVIRI data.

    Science.gov (United States)

    Jiang, Geng-Ming; Li, Zhao-Liang

    2008-11-10

    This work intercompared two Bi-directional Reflectance Distribution Function (BRDF) models, the modified Minnaert's model and the RossThick-LiSparse-R model, in the estimation of the directional emissivity in Middle Infra-Red (MIR) channel from the data acquired by the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) onboard the first Meteosat Second Generation (MSG1). The bi-directional reflectances in SEVIRI channel 4 (3.9 microm) were estimated from the combined MIR and Thermal Infra-Red (TIR) data and then were used to estimate the directional emissivity in this channel with aid of the BRDF models. The results show that: (1) Both models can relatively well describe the non-Lambertian reflective behavior of land surfaces in SEVIRI channel 4; (2) The RossThick-LiSparse-R model is better than the modified Minnaert's model in modeling the bi-directional reflectances, and the directional emissivities modeled by the modified Minnaert's model are always lower than the ones obtained by the RossThick-LiSparse-R model with averaged emissivity differences of approximately 0.01 and approximately 0.04 over the vegetated and bare areas, respectively. The use of the RossThick-LiSparse-R model in the estimation of the directional emissivity in MIR channel is recommended.

  12. Sol–gel synthesis and photoluminescence studies on colour tuneable Dy3+/Tm3+ co-doped NaGd(WO4)2 phosphor for white light emission

    International Nuclear Information System (INIS)

    Durairajan, A.; Balaji, D.; Rasu, K. Kavi; Moorthy Babu, S.; Hayakawa, Y.; Valente, M.A.

    2015-01-01

    A series of Dy 3+ /Tm 3+ ion co-doped NaGd(WO 4 ) 2 (NGW) phosphors were synthesised by a sol–gel method at low temperature for white light emission. The structural and luminescence properties of the synthesised phosphors were studied by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman and photoluminescence techniques. In Dy 3+ /Tm 3+ :NGW phosphors, the dopant ions substituted Gd 3+ ions that are located in S 4 sites of NGW host lattice. In NGW host, under UV excitation the Dy 3+ ions have shown strong yellow ( 4 F 9/2 → 6 H 13/2 ) and comparatively weak blue ( 4 F 9/2 → 6 H 15/2 ) emission transitions at 575 and 488 nm, respectively. Due to deficient blue colour the overall emission falls in yellow region. Hence, Tm 3+ ions having strong blue emission at 455 nm corresponding to the transition 1 D 2 → 3 F 4 were co-activated along with Dy 3+ ions in NGW matrix. By changing the doping concentrations of Tm 3+ and Dy 3+ ions in NGW, white light emission was tuned by 353 nm excitation wavelength. Their corresponding colour co-ordinates were calculated and found to be very close to the white colour chromaticity co-ordinates (0.333, 0.333). - Highlights: • Dy 3+ and Dy 3+ /Tm 3+ :NGW phosphors were synthesised by sol–gel methods. • The excitation spectrum confirmed the strong absorption in near-UV region. • The emission spectrum shows the yellow and white emission to doped and co-doped phosphors respectively. • The CIE co-ordinate conforms close to daylight emission

  13. Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

    International Nuclear Information System (INIS)

    Murphy, J. R.; Delikanli, S.; Demir, H. V.; Scrace, T.; Zhang, P.; Norden, T.; Petrou, A.; Thomay, T.; Cartwright, A. N.

    2016-01-01

    We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.

  14. Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J. R. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Delikanli, S.; Demir, H. V., E-mail: volkan@bilkent.edu.tr [LUMINOUS Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, Singapore 639798 (Singapore); Department of Electrical and Electronics Engineering, Department of Physics, UNAM−Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Scrace, T.; Zhang, P.; Norden, T.; Petrou, A., E-mail: petrou@buffalo.edu [Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Thomay, T.; Cartwright, A. N. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States)

    2016-06-13

    We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.

  15. Two-level quenching of photoluminescence in hexagonal boron nitride micropowder

    Energy Technology Data Exchange (ETDEWEB)

    Henaish, A. M. A. [Ural Federal University, NANOTECH Center, Mira Street, 19, Yekaterinburg, Russia, 620002 (Russian Federation); Tanta University, Physics Department, Tanta, Egypt, 31527 (Egypt); Vokhmintsev, A. S.; Weinstein, I. A., E-mail: i.a.weinstein@urfu.ru [Ural Federal University, NANOTECH Center, Mira Street, 19, Yekaterinburg, Russia, 620002 (Russian Federation)

    2016-03-29

    The processes of photoluminescence thermal quenching in the range RT – 800 K of h-BN micropowder in the 3.56 eV band were studied. It was found that two non-radiative channels of excitations relaxation with activation energies of 0.27 and 0.81 eV control the quenching for emission observed. It was assumed that emptying the shallow traps based on O{sub N}-centers characterized external quenching in RT – 530 K range and non-radiative mechanism of donor-acceptor recombination began to dominate at T > 530 K.

  16. Two-level quenching of photoluminescence in hexagonal boron nitride micropowder

    International Nuclear Information System (INIS)

    Henaish, A. M. A.; Vokhmintsev, A. S.; Weinstein, I. A.

    2016-01-01

    The processes of photoluminescence thermal quenching in the range RT – 800 K of h-BN micropowder in the 3.56 eV band were studied. It was found that two non-radiative channels of excitations relaxation with activation energies of 0.27 and 0.81 eV control the quenching for emission observed. It was assumed that emptying the shallow traps based on O N -centers characterized external quenching in RT – 530 K range and non-radiative mechanism of donor-acceptor recombination began to dominate at T > 530 K.

  17. Emission Channeling Investigation of Implantation Defects and Impurities in II-VI-Semiconductors

    CERN Multimedia

    Trojahn, I; Malamud, G; Straver, J; Ronnqvist, C; Jahn, S-G; Restle, M

    2002-01-01

    Detailed knowledge on the behaviour of implantation damage and its influence on the lattice position and environment of implanted dopants in II-VI-compound semiconductors is necessary for a clear interpretation of results from other investigation methods and finally for technical utilization. Besides, a precise localization of impurities could help to clarify the discussion about the instability of the electrical properties of some dopants, called " aging ".\\\\ \\\\We intend to use the emission channeling method to investigate: \\\\ \\\\i) The behaviour of implantation damage which shall be probed by the lattice location of isoelectronic isotopes (Zn,Cd,Hg,Se,Te) directly after implantation at different temperatures, doses and vacancy densities and after annealing treatments, and ii) the precise lattice sites of the acceptor Ag and donor In under different conditions by implanting precursors Cd and In isotopes. \\\\ \\\\Further on we would like to test the application of a two-dimensional position and energy sensitive e...

  18. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    International Nuclear Information System (INIS)

    Shimomura, K.; Kamiya, I.

    2015-01-01

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers

  19. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, K., E-mail: sd12502@toyota-ti.ac.jp; Kamiya, I., E-mail: kamiya@toyota-ti.ac.jp [Toyota Technological Institute 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-02-23

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers.

  20. New channeling effects in the radiative emission of 150 GeV electrons in a thin germanium crystal

    International Nuclear Information System (INIS)

    Belkacem, A.; Chevallier, M.; Gaillard, M.J.; Genre, R.; Kirsch, R.; Poizat, J.C.; Remillieux, J.; Bologna, G.; Peigneux, J.P.; Sillou, D.; Spighel, M.; Cue, N.; Kimball, J.C.; Marsh, B.; Sun, C.R.

    1986-01-01

    The orientation dependence of the radiative emission of 150 GeV electrons and positrons incident at small angles with respect to the axial direction of a thin (0.185 mm) Ge crystal has been observed. The processes are well understood, except for channeled electrons, which radiate unexpected high energy photons. (orig.)

  1. Emission channeling with short-lived isotopes lattice location of impurities in semiconductors and oxides

    CERN Multimedia

    We propose to perform emission channeling lattice location experiments in a number of semiconductor and oxide systems of technological relevance: \\\\- The lattice location of the transition metal probes $^{56}$Mn ($\\textit{t}_{1/2}$=2.6 h), $^{59}$Fe (45 d), $^{61}$Co (1.6 h) and $^{65}$Ni (2.5 h) is to be investigated in materials of interest as dilute magnetic semiconductors, such as GaMnAs, GaMnN, GaFeN, AlGaN, SiC, and in a number of oxides that are candidates for “single ion ferromagnetism”, in particular SrTiO$_3$ and LiNbO$_3$.\\\\- The topic of $\\textit{p}$-type doping of nitride semiconductors shall be addressed by studying the lattice sites of the acceptor dopants Mg and Be in GaN and AlN using the short-lived probes $^{27}$Mg (9.5 min) and $^{11}$Be (13.8 s). The aim is to reach a lattice location precision around 0.05 Å in order to provide critical tests for recent theoretical models which e.g. have predicted displacements of the Mg atom from the ideal substitutional Ga and Al sites of the order...

  2. Preparation and Photoluminescence of Tungsten Disulfide Monolayer

    Directory of Open Access Journals (Sweden)

    Yanfei Lv

    2018-05-01

    Full Text Available Tungsten disulfide (WS2 monolayer is a direct band gap semiconductor. The growth of WS2 monolayer hinders the progress of its investigation. In this paper, we prepared the WS2 monolayer through chemical vapor transport deposition. This method makes it easier for the growth of WS2 monolayer through the heterogeneous nucleation-and-growth process. The crystal defects introduced by the heterogeneous nucleation could promote the photoluminescence (PL emission. We observed the strong photoluminescence emission in the WS2 monolayer, as well as thermal quenching, and the PL energy redshift as the temperature increases. We attribute the thermal quenching to the energy or charge transfer of the excitons. The redshift is related to the dipole moment of WS2.

  3. Blue photoluminescent carbon nanodots from limeade

    Energy Technology Data Exchange (ETDEWEB)

    Suvarnaphaet, Phitsini [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); ThEP Center, Commission of Higher Education, 328 Si Ayuthaya Rd (Thailand); Tiwary, Chandra Sekhar [Department of Materials Science and Nano Engineering, Rice University, Houston, TX 7005 (United States); Wetcharungsri, Jutaphet; Porntheeraphat, Supanit [NECTEC, National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathumthani 12120 (Thailand); Hoonsawat, Rassmidara [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); ThEP Center, Commission of Higher Education, 328 Si Ayuthaya Rd (Thailand); Ajayan, Pulickel Madhavapanicker [Department of Materials Science and Nano Engineering, Rice University, Houston, TX 7005 (United States); Tang, I-Ming [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Department of Material Science, Faculty of Science, Kasetsart University, Bangkok 10400 (Thailand); ThEP Center, Commission of Higher Education, 328 Si Ayuthaya Rd (Thailand); Asanithi, Piyapong, E-mail: asanithi@hotmail.com [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); ThEP Center, Commission of Higher Education, 328 Si Ayuthaya Rd (Thailand)

    2016-12-01

    Carbon-based photoluminescent nanodot has currently been one of the promising materials for various applications. The remaining challenges are the carbon sources and the simple synthetic processes that enhance the quantum yield, photostability and biocompatibility of the nanodots. In this work, the synthesis of blue photoluminescent carbon nanodots from limeade via a single-step hydrothermal carbonization process is presented. Lime carbon nanodot (L-CnD), whose the quantum yield exceeding 50% for the 490 nm emission in gram-scale amounts, has the structure of graphene core functionalized with the oxygen functional groups. The micron-sized flake of the as-prepared L-CnD powder exhibits multicolor emission depending on an excitation wavelength. The L-CnDs are demonstrated for rapidly ferric-ion (Fe{sup 3+}) detection in water compared to Fe{sup 2+}, Cu{sup 2+}, Co{sup 2+}, Zn{sup 2+}, Mn{sup 2+} and Ni{sup 2+} ions. The photoluminescence quenching of L-CnD solution under UV light is used to distinguish the Fe{sup 3+} ions from others by naked eyes as low concentration as 100 μM. Additionally, L-CnDs provide exceptional photostability and biocompatibility for imaging yeast cell morphology. Changes in morphology of living yeast cells, i.e. cell shape variation, and budding, can be observed in a minute-period until more than an hour without the photoluminescent intensity loss. - Highlights: • Photoluminescent carbon nanodots are synthesized from limeade. • The quantum yield of lime carbon nanodots is higher than 50%. • The lime carbon nanodots can be applied for detecting of Fe{sup 3+} ions and for imaging living yeast cells.

  4. Game Theoretic Analysis of Carbon Emission Abatement in Fashion Supply Chains Considering Vertical Incentives and Channel Structures

    Directory of Open Access Journals (Sweden)

    Longfei He

    2015-04-01

    Full Text Available We study an emission-dependent dyadic fashion supply chain made up of a supplier and a manufacturer, both of which can reduce their own component/product emissions to serve the carbon-footprint sensitive consumers. With Carbon Tax regulation, we consider four scenarios resulting from two ways in form of adopting transfer price contract and/or introducing third-party emission-reduction service (TPERS to enhance the efficiency of systematic emission reductions. We refine four models from these corresponding scenarios, which in turn constitute a decision-making framework composed of determining vertical incentives and choosing supply chain structures. By exploiting Stackelberg games in all models, we compare their emission reduction efficiencies and profitability for each pair of settings. Theoretic analysis and numerical studies show that adopting vertical transfer payment schemes can definitely benefit channel carbon footprint reduction and Pareto improvement of supply chain profitability, regardless of whether the emission-reduction service exists or not. However, whether introducing TPERS or not is heavily depending on systematic parameters when the transfer payment incentive is adopted there. We also provide insights on the sensitivity of carbon tax parameters with respect to the supply chain performance, overall carbon emission reduction, vertical incentive and TPERS adopting decision-makings.

  5. A Critical Comparison of Alternative Distribution Configurations in Omni-Channel Retailing in Terms of Cost and Greenhouse Gas Emissions

    Directory of Open Access Journals (Sweden)

    Marco Melacini

    2018-01-01

    Full Text Available New opportunities and challenges forced by the ever-increasing importance of the online channel have arisen for retailers. The retailing industry is moving to a new phase, in which the distinctions between traditional and online channels disappear, namely omni-channel (OC retailing. At the same time, the awareness of environmentally sustainable processes has been enhanced around the world and the environmental impact that results from the online order fulfilment process is becoming a key issue for logistics managers. The new challenge is to understand how multiple channels can be synergistically managed to provide a seamless customer experience, taking an economic and environmental perspective simultaneously. Retailers need to define the distribution configuration for serving the online demand, making decisions on the integration level between online and traditional channels. In this paper, we developed an assessment model of the operational costs and greenhouse gas emissions for three distribution configurations in OC retailing. The model was also applied to a real case operating in the consumer electronics industry. Results highlighted that the search for synergies between online and traditional flows in both warehouse and transport activities is a key factor for the economic and environmental sustainability of OC systems.

  6. Multicolor photoluminescence in ITQ-16 zeolite film

    KAUST Repository

    Chen, Yanli

    2016-09-07

    Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photoluminescence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results indicate that Si―OH and non-bridging oxygen hole centers(NBOHCs) are responsible for the origin of green and red emissions at 540―800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals(≡SiO2), ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively. © 2016, Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH.

  7. Defect induced photoluminescence in MoS2 quantum dots and effect of Eu3+/Tb3+ co-doping towards efficient white light emission

    Science.gov (United States)

    Haldar, Dhrubaa; Ghosh, Arnab; Bose, Saptasree; Mondal, Supriya; Ghorai, Uttam Kumar; Saha, Shyamal K.

    2018-05-01

    Intensive research has been carried out on optical properties of MoS2 quantum dots for versatile applications in photo catalytic, sensing and optoelectronic devices. However, white light generation from MoS2 quantum dots particularly using doping effect is relatively unexplored. Herein we report successful synthesis of Europium (Eu)/Terbium (Tb) co-doped MoS2 quantum dots to achieve white light for potential applications in optoelectronic devices. The dopant ions are introduced into the host lattice to retain the emission colors to cover the entire range of visible light of solar spectrum. Perfect white light (CIE = 0.31, 0.33) with high intensity (quantum yield = 28.29%) is achieved in these rare earth elements co-doped quantum dot system. A new peak is observed in the NIR region which is attributed to the defects present in MoS2 quantum dots. Temperature dependent study has been carried out to understand the origin of this new peak in the NIR region. It is seen that the 'S' defects in the QDs cause the appearance of this peak which shows a blue shift at higher temperature.

  8. Proportion of influence phases anatase and rutile TiO{sub 2} in the photoluminescence 538 nm emission wavelength; Influencia da proporcao das fases anatasio e rutilo na fotoluminescincia do TiO{sub 2} em comprimento de onda de emissao de 538 nm

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M., E-mail: dagobertoufcg@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Viana, R.S.; Junior, S.A. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

    2016-07-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO{sub 2} molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm{sup 3} and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  9. Development of 40 channel waveform sampling CMOS ASIC board for Positron Emission Tomography

    International Nuclear Information System (INIS)

    Shimazoe, Kenji; Yeol, Yeom-Jung; Minamikawa, Yasuhiro; Tomida, Yuki; Takahashi, Hiroyuki; Fujita, Kaoru; Nakazawa, Masaharu; Murayama, Hideo

    2007-01-01

    We have designed and fabricated 10 channel/6-bit waveform sampling ASICs using ROHM 0.35 μm CMOS technology. This chip was designed for GSO-APD γ-ray detector and provides a function of 'waveform recording' at a sampling frequency of 100 MHz. This chip has 10 channel inputs and each channel has preamp/variable gain amplifier/6-bit folding ADC. The folding ADC greatly reduces the number of comparators and the power consumption of the chip. This chip provides a full function of recording a transient behavior of detector charge signals for each pulse. Self-trigger function is equipped with the system and this will enable simultaneous record of all input waveforms. Each channel has 64 words FIFO where each waveform data are stored. Stored data are converted to serial data and passed to an FPGA where we can implement a detailed signal processing. This chip is operated at 3.3 V and the power consumption is 1.2 W/chip. We have developed a data acquisition board using four bare chips. This board has 40 input channels and we plan to use this board for APD-based DOI-PET detector system which utilizes several different crystals to recognize depth positions by the difference in their decay times

  10. Lattice location of impurities in semiconductors: a RBS/channeling and proton-induced x-ray emission study

    Energy Technology Data Exchange (ETDEWEB)

    Kringhoj, P [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1994-12-31

    Rutherford backscattering spectrometry (RBS)/channeling and proton-induced x-ray emission (PIXE) are two well established and characterised techniques. Over the last three decades RBS/channeling measurements has been performed to extract the substitutional fraction of impurities in both elemental and compound semiconductors. However, due to the limitation of RBS, only elements heavier than the host crystal can be examined (except for a few elements, where a nuclear reaction or a resonance can be used). In silicon this limitation is acceptable, due to the low mass of Si, but in the III-V compounds (e.g. InP), the technique is limited to a few elements of hardly no technological or fundamental interest. One can overcome this by combining RBS/channeling with PIXE, where PIXE is applied to detect elements with a mass lower than the host crystal. In the present work, the lattice location of Ge in InP has been studied and compared to the group-III impurity Ga, and the group-VI impurity Se which is known to be a donor. The (RBS)/channeling technique has been used to detect not only the substitutional fraction, but also the relative population of the two sublattices. The half-width is approximately equal to the characteristic angle, {psi}{sub 1}. The channeling data obtained indicate that all three dopants are located exclusively on substitutional sites and that Ga is occuping the In position, Se theP position and that Ge is distributed equally between both sublattices. 6 refs., 1 tab., 3 figs.

  11. Lattice location of impurities in semiconductors: a RBS/channeling and proton-induced x-ray emission study

    Energy Technology Data Exchange (ETDEWEB)

    Kringhoj, P. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1993-12-31

    Rutherford backscattering spectrometry (RBS)/channeling and proton-induced x-ray emission (PIXE) are two well established and characterised techniques. Over the last three decades RBS/channeling measurements has been performed to extract the substitutional fraction of impurities in both elemental and compound semiconductors. However, due to the limitation of RBS, only elements heavier than the host crystal can be examined (except for a few elements, where a nuclear reaction or a resonance can be used). In silicon this limitation is acceptable, due to the low mass of Si, but in the III-V compounds (e.g. InP), the technique is limited to a few elements of hardly no technological or fundamental interest. One can overcome this by combining RBS/channeling with PIXE, where PIXE is applied to detect elements with a mass lower than the host crystal. In the present work, the lattice location of Ge in InP has been studied and compared to the group-III impurity Ga, and the group-VI impurity Se which is known to be a donor. The (RBS)/channeling technique has been used to detect not only the substitutional fraction, but also the relative population of the two sublattices. The half-width is approximately equal to the characteristic angle, {psi}{sub 1}. The channeling data obtained indicate that all three dopants are located exclusively on substitutional sites and that Ga is occuping the In position, Se theP position and that Ge is distributed equally between both sublattices. 6 refs., 1 tab., 3 figs.

  12. Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry.

    Science.gov (United States)

    McCloy, J S; Sundaram, S K; Matyas, J; Woskov, P P

    2011-05-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.

  13. X-ray and γ-ray emission from channeled relativistic electrons and positrons

    International Nuclear Information System (INIS)

    Terhune, R.W.; Pantell, R.H.

    1977-01-01

    The characteristics of the radiation from channeled relativistic electrons and positrons are discussed and model calculations carried out. Radiation near 2.5 keV associated with transitions etween the 2 p→1s eigenstates of 2-MeV electrons channeled along the axis of MgO is predicted with 50 times the usual bremsstrahlung intensity in a 10% bandwidth. Recent low-energy bremsstrahlung measurements made with 28-MeV electrons propagating along an axis in silicon are interpreted in terms of this model

  14. Enhanced photoluminescence from porous silicon by hydrogen-plasma etching

    International Nuclear Information System (INIS)

    Wang, Q.; Gu, C.Z.; Li, J.J.; Wang, Z.L.; Shi, C.Y.; Xu, P.; Zhu, K.; Liu, Y.L.

    2005-01-01

    Porous silicon (PS) was etched by hydrogen plasma. On the surface a large number of silicon nanocone arrays and nanocrystallites were formed. It is found that the photoluminescence of the H-etched porous silicon is highly enhanced. Correspondingly, three emission centers including red, green, and blue emissions are shown to contribute to the enhanced photoluminescence of the H-etched PS, which originate from the recombination of trapped electrons with free holes due to Si=O bonding at the surface of the silicon nanocrystallites, the quantum size confinement effect, and oxygen vacancy in the surface SiO 2 layer, respectively. In particular, the increase of SiO x (x<2) formed on the surface of the H-etched porous silicon plays a very important role in enhancing the photoluminescence properties

  15. Photoluminescence measurements of ZnO heterostructures

    International Nuclear Information System (INIS)

    Adachi, Yutaka; Sakaguchi, Isao; Ohashi, Naoki; Haneda, Hajime; Ryoken, Haruki; Takenaka, Tadashi

    2003-01-01

    ZnO thin films were grown on TbAlO 3 single crystal substrates by pulsed laser deposition. In photoluminescence (PL) measurements, strong emissions from TbAlO 3 were observed with the emission from ZnO when the film thickness was less than 100 nm. The relationship between the ZnO film thickness and the emission intensity from TbAlO 3 was investigated in order to determine the penetration depth of excitation light. Information on the heterostructures ranging from the surface to a depth of 300 nm was obtained by PL measurements in this study, and the absorption coefficient for a wavelength of 325 nm was estimated to be 1.31x10 5 cm -1 . (author)

  16. Emission channeling studies on transition-metal doped GaN and ZnO: Cation versus anion substitution

    CERN Document Server

    AUTHOR|(CDS)2070176; Wahl, Ulrich; Martins Correia, Joao; Amorim, Lígia; Silva, Daniel; Decoster, Stefan; Castro Ribeiro Da Silva, Manuel; Temst, Kristiaan; Vantomme, André

    2014-01-01

    The magnetic and electric properties of impurities in semiconductors are strongly dependent on the lattice sites which they occupy. While the majority site can often be predicted based on chemical similarities with the host elements and is usually simple to confirm experimentally, minority sites are far more complicated to predict, detect and identify. We have carried out extensive beta− emission channeling studies on the lattice location of transition metal impurities in wide-gap dilute magnetic semiconductors, namely Co and Mn in GaN and ZnO, making use of radioactive 61Co and 56Mn implanted at the ISOLDE facility at CERN. In addition to the majority occupation of cation (Ga, Zn) sites, we located significant fractions (of the order of 20%) of the Co and Mn impurities in anion (N, O) sites, which are virtually unaffected by thermal annealing up to 900 °C. Here, we present the beta− emission channeling experiments on 61Co-implanted GaN. We discuss these results in the context of our recent reports of mi...

  17. Drawing the geometry of 3d transition metal-boron pairs in silicon from electron emission channeling experiments

    CERN Document Server

    Silva, Daniel; Wahl, Ulrich; Martins Correia, Joao; Augustyns, Valerie; De Lemos Lima, Tiago Abel; Granadeiro Costa, Angelo Rafael; David Bosne, Eric; Castro Ribeiro Da Silva, Manuel; Esteves De Araujo, Araujo Joao Pedro; Da Costa Pereira, Lino Miguel

    2016-01-01

    Although the formation of transition metal-boron pairs is currently well established in silicon processing, the geometry of these complexes is still not completely understood. We investigated the lattice location of the transition metals manganese, iron, cobalt and nickel in n- and p+-type silicon by means of electron emission channeling. For manganese, iron and cobalt, we observed an increase of sites near the ideal tetrahedral interstitial position by changing the doping from n- to p+-type Si. Such increase was not observed for Ni. We ascribe this increase to the formation of pairs with boron, driven by Coulomb interactions, since the majority of iron, manganese and cobalt is positively charged in p+-type silicon while Ni is neutral. We propose that breathing mode relaxation around the boron ion within the pair causes the observed displacement from the ideal tetrahedral interstitial site. We discuss the application of the emission channeling technique in this system and, in particular, how it provides insi...

  18. Strong white photoluminescence from annealed zeolites

    International Nuclear Information System (INIS)

    Bai, Zhenhua; Fujii, Minoru; Imakita, Kenji; Hayashi, Shinji

    2014-01-01

    The optical properties of zeolites annealed at various temperatures are investigated for the first time. The annealed zeolites exhibit strong white photoluminescence (PL) under ultraviolet light excitation. With increasing annealing temperature, the emission intensity of annealed zeolites first increases and then decreases. At the same time, the PL peak red-shifts from 495 nm to 530 nm, and then returns to 500 nm. The strongest emission appears when the annealing temperature is 500 °C. The quantum yield of the sample is measured to be ∼10%. The PL lifetime monotonously increases from 223 μs to 251 μs with increasing annealing temperature. The origin of white PL is ascribed to oxygen vacancies formed during the annealing process. -- Highlights: • The optical properties of zeolites annealed at various temperatures are investigated. • The annealed zeolites exhibit strong white photoluminescence. • The maximum PL enhancement reaches as large as 62 times. • The lifetime shows little dependence on annealing temperature. • The origin of white emission is ascribed to the oxygen vacancies

  19. Tuning photoluminescence of ZnS nanoparticles by silver

    Indian Academy of Sciences (India)

    Wintec

    Ag@ZnS core-shell nanoparticles. ... doped ZnS NPs and thus changes the emission charac- teristics. We also ... Nanoparticles; photoluminescence; silver; zinc sulfide; doping. 1. ..... Sooklal K, Brain S, Angel M and Murphy C J 1996 J. Phys.

  20. Optical emissions from an ionized channel produced by an electron beam

    International Nuclear Information System (INIS)

    Fessenden, T.J.

    1977-01-01

    Quantitative measurements of the visible light generated by the Astron beam (5 MeV, 400 A) in passing through 500 torr air and nitrogen are reported. Experiments show that in the presence of the beam, the light is from .01 to 0.1 percent sun's brightness. After the beam, the light decays extremely rapidly. The size and position of the beam in the gas can be determined from observations of the channel light

  1. Entrance channel dependent light-charged particle emission of the 156Er compound

    International Nuclear Information System (INIS)

    Liang, J.F.; Bierman, J.D.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R.; van Schagen, J.P.S.

    1996-01-01

    Light-charged particle decay from the 156 Er compound nucleus, populated by 12 C+ 144 Sm and 60 Ni+ 96 Zr at the same excitation energy, were measured in coincidence with the evaporation residues. The high energy slope of charged particle spectra for the 60 Ni-induced reaction is steeper than for the 12 C-induced reaction. Model calculations including particle evaporation during compound nucleus formation result in good agreement with the data. This suggests that the difference in the charged particle spectra between the two entrance channels is due to a longer formation time in the 60 Ni-induced reaction. 14 refs., 3 figs

  2. Multiple particle emission after 11Li beta-decay: exploring new decay channels

    International Nuclear Information System (INIS)

    Madurga, M.; Borge, M. J. G.; Fynbo, H. O. U.; Prezado, Y.; Tengblad, O.; Jonson, B.; Nyman, G.; Riisager, K.

    2007-01-01

    We present here a study of the three-body, nα 6 He particle break-up of 11 Be(10.6) following 11 Li β-decay. The emitted charged particles were detected in coincidence using a cubic set-up of highly segmented silicon detectors, allowing us to measure simultaneously energy and trajectory. The three body break-up of 11 Be(10.5) through the intermediate state 10 Be(9.6) was modeled using the multiple-level single-channel R-Matrix formalism

  3. The nature of the photoluminescence in amorphized PZT

    International Nuclear Information System (INIS)

    Silva, M.S.; Cilense, M.; Orhan, E.; Goes, M.S.; Machado, M.A.C.; Santos, L.P.S.; Paiva-Santos, C.O.; Longo, E.; Varela, J.A.; Zaghete, M.A.; Pizani, P.S.

    2005-01-01

    The polymeric precursor method was used to synthesize lead zirconate titanate powder (PZT). The crystalline powder was then amorphized by a high-energy ball milling process during 120 h. A strong photoluminescence emission was observed at room temperature for the amorphized PZT powder. The powders were characterized by XRD and the percentage of amorphous phase was calculated through Rietveld refinement. The microstructure for both phases was investigated by TEM. The optical gap was calculated through the Wood and Tauc method using the UV-Vis. data. Quantum mechanical calculations were carried out to give an interpretation of the photoluminescence in terms of electronic structure

  4. Characteristics of exciton photoluminescence kinetics in low-dimensional silicon structures

    CERN Document Server

    Sachenko, A V; Manojlov, E G; Svechnikov, S V

    2001-01-01

    The time-resolved visible photoluminescence of porous nanocrystalline silicon films obtained by laser ablation have been measured within the temperature range 90-300 K. A study has been made of the interrelationship between photoluminescence characteristics (intensity, emission spectra, relaxation times, their temperature dependencies and structural and dielectric properties (size and shapes of Si nanocrystals, oxide phase of nanocrystal coating, porosity). A photoluminescence model is proposed that describes photon absorption and emission occurring in quantum-size Si nanocrystals while coupled subsystems of electron-hole pairs and excitons take part in the recombination. Possible excitonic Auger recombination mechanism in low-dimensional silicon structures is considered

  5. Possibility of adjusting the photoluminescence spectrum of Ca scheelites to the emission spectrum of incandescent lamps: [ nCaWO4-(1- n)CaMoO4]: Eu3+ solid solutions

    Science.gov (United States)

    Bakovets, V. V.; Zolotova, E. S.; Antonova, O. V.; Korol'kov, I. V.; Yushina, I. V.

    2016-12-01

    The specific features of the photoluminescence of [ nCaWO4-(1- n)CaMoO4]:Eu3+ solid solutions with the scheelite structure are examined using X-ray phase analysis and photoluminescence, Raman scattering, and diffuse reflectance spectroscopy. The studied features are associated with a change in the long- and short-range orders of the crystal lattice upon variations in the composition of solutions in the range n = 0-1.0 (with a pitch of 0.2) at a concentration of red photoluminescence activator Eu3+ of 2 mol %. The mechanism of the modification of photoluminescence of solid solutions upon variations in their composition has been discussed. Anomalies in the variations in parameters of the crystal lattice, its short-range order, and luminescence spectra have been observed in the transition from pure compounds CaMoO4:Eu3+ and CaWO4:Eu3+ to solutions; the concentration of Eu3+ ions in the centrosymmetric localization increases (decreases) in the transition from the molybdate (tungstate). It has been demonstrated that the spectral radiant emittance of solid solution [0.4CaWO4-0.6CaMoO4]:Eu3+ (2 mol %) is the closest to that of an incandescent lamp.

  6. Dependence of photoluminescence (PL) emission intensity on Eu3+ and ZnO concentrations in Y2O3:Eu3+ and ZnO·Y2O3:Eu3+ nanophosphors

    CSIR Research Space (South Africa)

    Mhlongo, GH

    2011-08-01

    Full Text Available Y2O3:Eu3+ and ZnO·Y2O3:Eu3+ nanophosphor powders with different concentrations of Eu3+ ions were synthesized by a sol–gel method and their luminescence properties were investigated. The red photoluminescence (PL) from Eu3+ ions with the main...

  7. Photoluminescence properties of Co-doped ZnO nanocrystals

    DEFF Research Database (Denmark)

    Lommens, P.; Smet, P.F.; De Mello Donega, C.

    2006-01-01

    We performed photoluminescence experiments on colloidal, Co -doped ZnO nanocrystals in order to study the electronic properties of Co in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co dopant. The spectral...... position and width of this emission does not depend on particle size or Co concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co-emission band. We conclude that Co ions are strongly localized in the ZnO host, making the formation of a Co d-band unlikely. Magnetic measurements...

  8. Photoluminescence study of as-grown vertically standing wurtzite InP nanowire ensembles.

    Science.gov (United States)

    Iqbal, Azhar; Beech, Jason P; Anttu, Nicklas; Pistol, Mats-Erik; Samuelson, Lars; Borgström, Magnus T; Yartsev, Arkady

    2013-03-22

    We demonstrate a method that enables the study of photoluminescence of as-grown nanowires on a native substrate by non-destructively suppressing the contribution of substrate photoluminescence. This is achieved by using polarized photo-excitation and photoluminescence and by making an appropriate choice of incident angle of both excitation beam and photoluminescence collection direction. Using TE-polarized excitation at a wavelength of 488 nm at an incident angle of ∼70° we suppress the InP substrate photoluminescence relative to that of the InP nanowires by about 80 times. Consequently, the photoluminescence originating from the nanowires becomes comparable to and easily distinguishable from the substrate photoluminescence. The measured photoluminescence, which peaks at photon energies of ∼1.35 eV and ∼1.49 eV, corresponds to the InP substrate with zinc-blende crystal structure and to the InP nanowires with wurtzite crystal structure, respectively. The photoluminescence quantum yield of the nanowires was found to be ∼20 times lower than that of the InP substrate. The nanowires, grown vertically in a random ensemble, neither exhibit substantial emission polarization selectivity to the axis of the nanowires nor follow excitation polarization preferences observed previously for a single nanowire.

  9. Characterization of CdSe polycrystalline films by photoluminescence spectroscopy

    International Nuclear Information System (INIS)

    Brasil, M.J.S.P.

    1985-01-01

    The characterization of CdSe polycristalline films were done by photoluminescence spectroscopy, X-ray diffraction analysis, diagrams IxV, and efficiency of solar energy conversion for cells done by these films. The experimental data shown strong temperature dependence of annealing, and the optimum temperature around 650 0 C was determined. The films did not present photoluminescence before heat treatment, but the annealed sample spectrum showed fine structures in the excitonic region, crystal phase transformation, enhancement of grain size, and better efficiency of the cell. Measurements of photoluminescence between 2 and 300 K, showed two bands of infrared emission, width and intense enough. The shape, at half-width, and the integrated intensity of one these bands were described by a configuration coordinate model for deep centers. Based on obtained results, some hypothesis about the origin of these bands and its correlation with efficiency of cells done with CdSe polycrystalline films, are proposed. (M.C.K.) [pt

  10. Denitrification capacity and greenhouse gas emissions of soils in channelized and restored reaches along an Alpine river corridor

    Science.gov (United States)

    Shrestha, Juna; Niklaus, Pascal; Samaritani, Emanuela; Frossard, Emmanuel; Tockner, Klement; Luster, Jörg

    2010-05-01

    In order to assess the effects of river restoration on water and air quality, the biogeochemical functions of channelized and restored river reaches have to be quantified. The objective of this study was to compare denitrification potential and greenhouse gas emissions of functional processing zones (FPZ) in a channelized and a recently restored reach of the alpine river Thur in north-eastern Switzerland. The study was part of the project cluster RECORD of the ETH domain, Switzerland, which was initiated to increase the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The denitrification potential represents an important aspect of the soil filter function related to water quality. Besides, it also contributes to the emission of greenhouse gases. Extensively used pasture growing on a sandy loam is the characteristic FPZ of the channelized section. The restored section encompasses five FPZ: (i) bare gravel bars sparsely colonized by plants, (ii) gravel bars densely colonized by grass (mainly canary reed grass with up to 80 cm sandy deposits), (iii) mixed forest dominated by ash and maple, (iv) riparian forest dominated by willow (Salix alba), (v) older overbank sediments stabilized during restoration with young willows separating the forests from the river-gravel bar system (willow bush). The FPZ were sampled in January, April, August and October 2009. In addition, in June and July 2009 two flood events were monitored in the restored section with more frequent samplings. At each date, topsoil samples were collected in each FPZ (four replicates per samples) and analyzed for denitrifier enzyme activity (DEA). In addition, gas samples were taken in-situ using the closed chamber technique to measure soil respiration as well as N2O and CH4 fluxes. In all FPZ, the denitrification potential was mainly governed by soil moisture. It was highest in the willow forest exhibiting low spatial variability. The DEA in pasture, grass zone

  11. Multi-channel electronics for secondary emission grid profile monitor of TTF linac

    International Nuclear Information System (INIS)

    Reingardt-Nikoulin, P.; Gaidash, V.; Mirzojan, A.; Kocharyan, V.; Noelle, D.

    2004-01-01

    According to the TTF beam experimental program, a measurement f the time dependence of the energy spread within the bunch train should be done by means of a standard device for profile measurements, that is Secondary Emission Grid (SEMG). SEMG on the high-energy TTF beam is placed in the focal plane of the magnet spectrometer. It should measure the total energy spread in the range from 0.1% up to a few percents for any single or any group of electron bunches in the bunch train of TTF Linac. SEMG profile measurements with new high sensitive electronics are described. Beam results of SEMG Monitor test are given for two modifications of an electronic preamplifier

  12. Correlation between surface modification and photoluminescence properties of β-Ga2O3 nanostructures

    Directory of Open Access Journals (Sweden)

    R. Jangir

    2016-03-01

    Full Text Available In this work three different growth methods have been used to grow β-Ga2O3 nanostructures. The nanostructures were characterized by Grazing Incident X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Photoluminescence Spectroscopy. Photoluminescence spectra for all the samples of β-Ga2O3 nanostructures exhibit an UV and blue emission band. The relative intensity of UV and blue luminescence is strongly affected by the surface defects present on the nanostructures. Our study shows that Photoluminescence intensity of UV and blue luminescence can be reliably used to determine the quality of β-Ga2O3 nanostructures. Further the work opens up the possibility of using UV excitation and subsequent Photoluminescence analysis as a possible means for oxygen sensing. The Photoluminescence mechanism in β-Ga2O3 nanostructures is also discussed.

  13. New organically templated photoluminescence iodocuprates(I)

    International Nuclear Information System (INIS)

    Hou Qin; Zhao Jinjing; Zhao Tianqi; Jin Juan; Yu Jiehui; Xu Jiqing

    2011-01-01

    Two types of organic cyclic aliphatic diamine molecules piperazine (pip) and 1,3-bis(4-piperidyl)propane (bpp) were used, respectively, to react with an inorganic mixture of CuI and KI in the acidic CH 3 OH solutions under the solvothermal conditions, generating finally three new organically templated iodocuprates as 2-D layered [(Hpip)Cu 3 I 4 ] 1, 1-D chained [tmpip][Cu 2 I 4 ] 2 (tmpip=N,N,N',N'-tetramethylpiperazinium) and dinuclear [H 2 bpp] 2 [Cu 2 I 5 ] I.2H 2 O 3. Note that the templating agent tmpip 2+ in compound 2 originated from the in situ N-alkylation reaction between the pip molecule and the methanol solvent. The photoluminescence analysis indicates that the title compounds emit the different lights: yellow for 1, blue for 2 and yellow-green for 3, respectively. - Graphical abstract: The solvothermal self-assemblies of CuI, KI and pip/bpp in acidic CH 3 OH solutions created three iodocuprates 2-D layered [(Hpip)Cu 3 I 4 ] 1, 1-D chained [tmpip][Cu 2 I 4 ] 2 and dinuclear [H 2 bpp] 2 [Cu 2 I 5 ] I.2H 2 O 3. Highlights: → A new layered iodocuprate(I) with 20-membered rings was hydrothermally prepared. → A simple approach to prepare the new organic templating agent was reported. → Photoluminescence analysis indicates the emission for iodocuprate(I) is associated with the Cu...Cu interactions.

  14. Discharge on boiling in a channel: effect of channel geometry on the performance characteristics of determining metals in a liquid flow by atomic emission spectrometry

    International Nuclear Information System (INIS)

    Zuev, B.K.; Yagov, V.V.; Grachev, A.S.

    2006-01-01

    Discharge on boiling in a channel was studied as a new atomization and excitation source for spectrochemical analysis in a flow of electrolyte solutions. The discharge arises between the liquid walls of a vapor lock formed in the channel of a dielectric membrane because of the rapid Joule heating of the liquid in the channel. The effect of channel geometry on the reproducibility of the integrated light intensity was studied. The background radiation spectrum was measured over the range 220-900 nm, and the possibility of determining alkali and alkaline earth metals in a flow was studied. The parameters of linear calibration equations and the detection limits for these metals are given [ru

  15. Modelling absorption and photoluminescence of TPD

    Energy Technology Data Exchange (ETDEWEB)

    Vragovic, Igor [Dpto. de Fisica Aplicada and Inst. Universitario de Materiales de Alicante, Universidad de Alicante, E-03080 Alicante (Spain)], E-mail: igor.vragovic@ua.es; Calzado, Eva M.; Diaz Garcia, Maria A.; Himcinschi, C. [Max-Planck-Institut fuer Mikrostrukturphysik, D-06120 Halle (Germany); Gisslen, L.; Scholz, R. [Walter Schottky Institut, Technische Universitaet Muenchen, D-85748 Garching (Germany)

    2008-05-15

    We analyse the optical spectra of N,N{sup '}-diphenyl-N,N{sup '}-bis(3-methyl-phenyl)-(1,1{sup '}-biphenyl)-4,4{sup '}-diamine (TPD) doped polystyrene films. The aim of the present paper is to give a microscopic interpretation of the significant Stokes shift between absorption and photoluminescence, which makes this material suitable for stimulated emission. The optimized geometric structures and energies of a neutral TPD monomer in ground and excited states are obtained by ab initio calculations using Hartree-Fock and density functional theory. The results indicate that the second distinct peak observed in absorption may arise either from a group of higher electronic transitions of the monomer or from the lowest optical transitions of a TPD dimer.

  16. Modelling absorption and photoluminescence of TPD

    International Nuclear Information System (INIS)

    Vragovic, Igor; Calzado, Eva M.; Diaz Garcia, Maria A.; Himcinschi, C.; Gisslen, L.; Scholz, R.

    2008-01-01

    We analyse the optical spectra of N,N ' -diphenyl-N,N ' -bis(3-methyl-phenyl)-(1,1 ' -biphenyl)-4,4 ' -diamine (TPD) doped polystyrene films. The aim of the present paper is to give a microscopic interpretation of the significant Stokes shift between absorption and photoluminescence, which makes this material suitable for stimulated emission. The optimized geometric structures and energies of a neutral TPD monomer in ground and excited states are obtained by ab initio calculations using Hartree-Fock and density functional theory. The results indicate that the second distinct peak observed in absorption may arise either from a group of higher electronic transitions of the monomer or from the lowest optical transitions of a TPD dimer

  17. Detection of certain minerals of uranium, zinc, lead and other metals using photoluminescence

    International Nuclear Information System (INIS)

    Seigel, H.O.; Robbins, J.C.

    1980-01-01

    We have discovered that certain photoluminescent minerals of uranium, lead, zinc, fluorine, tungsten and other elements which may naturally occur at the surface of the earth can be selectively detected in the presence of most other photoluminescent minerals and organic materials which are likely to occur at the earth's surface. The base of selective ldetection is the discovery that the lifetimes of photoluminescent emission of materials in the latter class are much shorter than the lifetimes of photoluminescent emission of materials in the former class. This invention utilizes this discovery in the detection of minerals of uranium, zinc, lead, flourine, tungsten, molybdenum, mercury and other elements. In one embodiment of the invention, using a laser or other short duration source of optical excitation, measurements of the photoluminescent response of the earth are made at times sufficiently long for the photoluminescence of other common and unwanted sources to have substantially decayed, thereby selectively detection and identifying certain minerals of potiential economic interest. In another embodiment a source of light is modulated at a predetermined frequency and the photoluminescent response of the earth which is out-of-phase with the source is measured. In a third embodiment this source of light may be incident solar radiation after passage through asuitable modulator

  18. Chitosan/ZnAl_2O_4 films: structural evaluation and photoluminescent

    International Nuclear Information System (INIS)

    Araujo, P.M.A.G.; Costa, A.C.F.M.

    2014-01-01

    The photoluminescent materials have been the focus of intense research and applications in optics, electronics and biological areas. This work reports obtaining chitosan/ZnAl_2O_4 film in proportions of 1: 1, 1: 2, 1: 3, 1:4 to 1:5 by weight, and assess the structural properties of the films and photoluminescence. The samples were characterized by XRD, FTIR, emission and excitation. By XRD was found that all samples showed characteristic peaks of chitosan and ZnAl_2O_4. The FTIR spectra for all concentrations of Qs/NPs films exhibit characteristic bands of Qs and trend banding of ions ZnAl_2O_4. The emission and excitation spectra revealed the presence of a broadband processes associated with charge transfer to the Al"3"+ O"2"-, all samples showed good photoluminescent properties being that higher intensities of photoluminescence gave to the film concentration 1:4 being promising for photoelectronic applications. (author)

  19. Structural and photoluminescence properties of Si-based nanosheet bundles rooted on Si substrates

    Science.gov (United States)

    Yuan, Peiling; Tamaki, Ryo; Kusazaki, Shinya; Atsumi, Nanae; Saito, Yuya; Kumazawa, Yuki; Ahsan, Nazmul; Okada, Yoshitaka; Ishida, Akihiro; Tatsuoka, Hirokazu

    2018-04-01

    Si-based nanosheet bundles were synthesized by the extraction of Ca atoms from CaSi2 microwalls grown on Si substrates by inositol hexakisphosphate solution or thermal treatment in FeCl2 vapor. The structural and photoluminescence properties of the Si-based nanosheet bundles were examined. The photoluminescence emissions in the visible region were clearly observed, and the temperature and excitation intensity dependences of the emissions were characterized. The observed Si-based nanosheets consist of thin Si layers, and a superlattice-like layered structural model is proposed to describe the Si-based nanosheet bundle structures and their photoluminescence property. The photoluminescence property of the nanosheets significantly depends on their treatment process. The luminescence mechanism of the nanosheets was discussed.

  20. Photoluminescence study of aligned ZnO nanorods grown using chemical bath deposition

    International Nuclear Information System (INIS)

    Urgessa, Z.N.; Oluwafemi, O.S.; Dangbegnon, J.K.; Botha, J.R.

    2012-01-01

    The photoluminescence study of self-assembled ZnO nanorods grown on a pre-treated Si substrate by a simple chemical bath deposition method at a temperature of 80 °C is hereby reported. By annealing in O 2 environment the UV emission is enhanced with diminishing deep level emission suggesting that most of the deep level emission is due to oxygen vacancies. The photoluminescence was investigated from 10 K to room temperature. The low temperature photoluminescence spectrum is dominated by donor-bound exciton. The activation energy and binding energy of shallow donors giving rise to bound exciton emission were calculated to be around 13.2 meV, 46 meV, respectively. Depending on these energy values and nature of growth environment, hydrogen is suggested to be the possible contaminating element acting as a donor.

  1. Photoluminescence study of aligned ZnO nanorods grown using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Urgessa, Z.N. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S. [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Dangbegnon, J.K. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Botha, J.R., E-mail: Reinhardt.Botha@nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    The photoluminescence study of self-assembled ZnO nanorods grown on a pre-treated Si substrate by a simple chemical bath deposition method at a temperature of 80 Degree-Sign C is hereby reported. By annealing in O{sub 2} environment the UV emission is enhanced with diminishing deep level emission suggesting that most of the deep level emission is due to oxygen vacancies. The photoluminescence was investigated from 10 K to room temperature. The low temperature photoluminescence spectrum is dominated by donor-bound exciton. The activation energy and binding energy of shallow donors giving rise to bound exciton emission were calculated to be around 13.2 meV, 46 meV, respectively. Depending on these energy values and nature of growth environment, hydrogen is suggested to be the possible contaminating element acting as a donor.

  2. Photoluminescence under high-electric field of PbS quantum dots

    Directory of Open Access Journals (Sweden)

    B. Ullrich

    2012-12-01

    Full Text Available The effect of a laterally applied electric field (≤10 kV/cm on the photoluminescence of colloidal PbS quantum dots (diameter of 2.7 nm on glass was studied. The field provoked a blueshift of the emission peak, a reduction of the luminescent intensity, and caused an increase in the full width at half maximum of the emission spectrum. Upon comparison with the photoluminescence of p-type GaAs exhibits the uniqueness of quantum dot based electric emission control with respect to bulk materials.

  3. Inorganic pigments doped with tris(pyrazol-1-yl)borate lanthanide complexes: A photoluminescence study

    Energy Technology Data Exchange (ETDEWEB)

    Gheno, Giulia, E-mail: giulia.gheno@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari di Venezia, Dorsoduro 2137, 30123 Venezia (Italy); Bortoluzzi, Marco; Ganzerla, Renzo [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari di Venezia, Dorsoduro 2137, 30123 Venezia (Italy); Enrichi, Francesco [CIVEN, Coordinamento Interuniversitario Veneto per le Nanotecnologie, Via delle Industrie 5, 30175 Marghera, Venezia (Italy)

    2014-01-15

    The inorganic pigments malachite, Egyptian blue, Ercolano blue and chrome yellow have been doped with the neutral homoleptic Ln(III) complex Ln(Tp){sub 3} (Ln=Eu, Tb; Tp=hydrotris(pyrazol-1-yl)borate) in the presence of arabic gum or acrylic emulsion as binders, in order to obtain photoluminescent materials of interest for cultural heritage restoration. The doped pigments have shown emissions associated to f–f transitions in the visible range upon excitation with UV light. Thermal and UV-light ageings have been carried out. In all the cases the photoluminescent behaviour is maintained, but in the cases of acrylic-based paints emission spectra and lifetimes are strongly influenced by thermal treatments. The choice of binder and pigments influences the photoluminescent behaviour of the corresponding film paints. -- Highlights: • Inorganic pigments doped with photoluminescent lanthanide complexes. • Hydrotris(pyrazol-1-yl)borate (Tp) as antenna-ligand for Eu(III) and Tb(III). • Emission associated to f–f transitions upon excitation with UV light. • Photoluminescence of paints influenced by the choice of binder and pigments. • Photoluminescence after ageing depending upon the type of binder.

  4. Photoluminescence of spray pyrolysis deposited ZnO nanorods

    Directory of Open Access Journals (Sweden)

    Mikli Valdek

    2011-01-01

    Full Text Available Abstract Photoluminescence of highly structured ZnO layers comprising well-shaped hexagonal rods is presented. The ZnO rods (length 500-1,000 nm, diameter 100-300 nm were grown in air onto a preheated soda-lime glass (SGL or ITO/SGL substrate by low-cost chemical spray pyrolysis method using zinc chloride precursor solutions and growth temperatures in the range of 450-550°C. We report the effect of the variation in deposition parameters (substrate type, growth temperature, spray rate, solvent type on the photoluminescence properties of the spray-deposited ZnO nanorods. A dominant near band edge (NBE emission is observed at 300 K and at 10 K. High-resolution photoluminescence measurements at 10 K reveal fine structure of the NBE band with the dominant peaks related to the bound exciton transitions. It is found that all studied technological parameters affect the excitonic photoluminescence in ZnO nanorods. PACS: 78.55.Et, 81.15.Rs, 61.46.Km

  5. Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically bent crystal

    International Nuclear Information System (INIS)

    Krause, W.; Korol, A.V.; Department of Physics, St Petersburg State Maritime Technical University, Leninskii prospect 101, St Petersburg 198262; Solov'yov, A.V.; AF Ioffe Physical-Technical Institute of the Academy of Sciences of Russia, Polytechnicheskaya 26, St Petersburg 194021; Greiner, W.

    2000-01-01

    We present the results of numerical calculations of the channelling and undulator radiation generated by ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due to either the propagation of a transverse acoustic wave through the crystal, or the static strain as it occurs in superlattices. The periodically bent crystal serves as an undulator. We investigate the dependence of the intensities of both the ordinary channelling and the undulator radiations on the parameters of the periodically bent channel with simultaneous account for the de-channelling effect of the positrons. We demonstrate that there is a range of parameters in which the undulator radiation dominates over the channelling one and the characteristic frequencies of both types of radiation are well separated. This result is important, because the undulator radiation can be used to create a tunable source of x-ray and γ-radiation. (author). Letter-to-the-editor

  6. Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

    KAUST Repository

    Chaieb, Sahraoui

    2015-04-09

    Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

  7. Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon

    KAUST Repository

    Chaieb, Saharoui; Mughal, Asad Jahangir

    2015-01-01

    Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.

  8. Photoluminescence of ZnBeMnSe solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Strzałkowski, K., E-mail: skaroll@fizyka.umk.pl; Firszt, F.; Marasek, A.

    2017-04-15

    In this paper optical properties of Zn{sub 1-x-y}Be{sub x}Mn{sub y}Se mixed semiconductors were studied as a function of both, temperature and excitation power. The crystals under investigation were grown by the high-pressure, high-temperature vertical Bridgman technique within the range of the composition 0.05≤x, y≤0.2. Photoluminescence spectra for the lowest content of Mn and Be exhibit character typical for II-VI semiconductors together with intensive yellow-orange manganese emission. Evolution of the excitonic emission as the function of temperature allowed determining the energy gap of the investigated semiconductors. Absorbance and photoluminescence excitation spectra confirmed crystal field splitting of excited atomic terms of manganese ions into the states, denoted according to the crystal field theory in the case of tetrahedral symmetry. Temperature and laser power dependences of luminescence showed anomalous behavior of the manganese emission. It turned out that the position of the Mn{sup 2+} related luminescence band does not change monotonically with the variation of the temperature or the excitation power. Finally, switching of the manganese emission has been observed. By increasing laser power of exciting radiation, the Mn-related emission could be quenched by almost two orders in magnitude. This effect was especially strong at low temperature and it was fully reversible.

  9. Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

    International Nuclear Information System (INIS)

    Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

    2013-01-01

    A novel metal organic framework (MOF) formulated as [Eu(H 2 O) 2 (fdc)(ox) 0.5 ·(H 2 O)] n (1, fdc 2− =2,5-furandicarboxylate, ox 2− =oxalate), was hydrothermally synthesized via in situ ox 2− generation from the partial decomposition of the fdc 2− ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H 2 O, ox 2− and fdc 2− ) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu 3+ red emission and the differences observed reflects the slightly different structures of these polymorphs. - Graphical abstract: Exploring metal organic framework polymorphism in the system Eu(H 2 O) 2 (fdc)(ox) 0.5 ·(H 2 O)] n (fdc 2− =2,5-furandicarboxylate, ox 2− =oxalate) for tuning light emission. Display Omitted - Highlights: • Synthesis of Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOF polymorphs. • Detailed single-crystal study of polymorphs including hydrogen-bonding networks. • Photoluminescence spectroscopy show subtle differences light emission properties

  10. Rhodamine 6G impregnated porous silica: A photoluminescence study

    Energy Technology Data Exchange (ETDEWEB)

    Anedda, A. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy); Carbonaro, C.M. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy)]. E-mail: cm.carbonaro@dsf.unica.it; Clemente, F. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Corpino, R. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Ricci, P.C. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Rossini, S. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy)

    2005-12-15

    The optical properties of rhodamine 6G dye confined in porous silica are reported. Photoluminescence properties of embedded chromophores in mesoporous hosts can be affected by the surrounding matrices: shifts in emission spectra and variations of photoluminescence quantum yield are found as compared to dye solutions. Host-guest interactions are studied here by varying both SiO{sub 2} xerogels porosity and the dye concentration. Comparing samples obtained by impregnating matrices with 5.4 and 18.2 nm pores with solutions having concentrations in the rhodamine 6G high laser gain, matrices with 5.4 nm pores impregnated with a dye concentration of 5 x 10{sup -4} M are found to be the most stable and efficient in the examined range.

  11. Photoluminescence of nanocrystals embedded in oxide matrices

    International Nuclear Information System (INIS)

    Estrada, C.; Gonzalez, J.A.; Kunold, A.; Reyes-Esqueda, J.A.; Pereyra, P.

    2006-12-01

    We used the theory of finite periodic systems to explain the photoluminescence spectra dependence on the average diameter of nanocrystals embedded in oxide matrices. Because of the broad matrix band gap, the photoluminescence response is basically determined by isolated nanocrystals and sequences of a few of them. With this model we were able to reproduce the shape and displacement of the experimentally observed photoluminescence spectra. (author)

  12. Analysis of Carbon Emission Reduction in a Dual-Channel Supply Chain with Cap-And-Trade Regulation and Low-Carbon Preference

    Directory of Open Access Journals (Sweden)

    Xiaoyan Wang

    2018-02-01

    Full Text Available This paper focuses on the reduction of carbon emissions driven by cap-and-trade regulation and consumers’ low-carbon preference in a dual-channel supply chain. Under the low-carbon environment, we also discuss the pricing strategies and the profits for the supply chain members using the Stackelberg game model in two cases. In the first (second case where the initial proportion of consumers who prefer the online direct channel (traditional retail channel is “larger”, the direct sale price of low-carbon products could be set higher than (equal to the wholesale price. And it is shown that in both cases, tighter cap-and-trade regulation and higher low-carbon preference stimulate the manufacturer to cut carbon emissions in its production process. However, improving consumers’ low-carbon preference is more acceptable to the supply chain members. It always benefits the manufacturer and the retailer. In comparison, the firm’s profit increases with carbon price only when the clean production level is relatively high. Our findings can provide useful managerial insights for policy-makers and firms in the development of low-carbon sustainability.

  13. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  14. Photoluminescence properties of perovskite multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Macario, Leilane Roberta; Longo, Elson, E-mail: leilanemacario@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil); Mazzo, Tatiana Martelli [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Bouquet, Valerie; Deputier, Stephanie; Ollivier, Sophie; Guilloux-Viry, Maryline [Universite de Rennes (France)

    2016-07-01

    Full text: The knowledge of the optical properties of thin films is important in many scientific, technological and industrial applications of thin films such as photoconductivity, solar energy, photography, and numerous other applications [1]. In this study, perovskite type oxides were grown by pulsed laser deposition [2] in order to obtain thin films with applicable optical properties. The LaNiO{sub 3} (LN), BaTiO{sub 3} (BT) and KNbO{sub 3} (KNb) targets were prepared by solid-state reaction. The X-ray Diffraction revealed the presence of the desired phases, containing the elements of interest in the targets and in the thin films that were produced. The LN, BT and KNb thin films were polycrystalline and the corresponding diffraction peaks were indexed in the with JCPDS cards n. 00-033-0711, n. 00-005-0626, and n. 00-009-0156, respectively. The multilayers films were polycrystalline. The majority of the micrographs obtained by scanning electron microscopy presented films with a thickness from 100 to 400 nm. The photoluminescent (PL) emission spectra of thin films show different broad bands that occupies large region of the visible spectrum, ranging from about 300-350 to 600-650 nm of the electromagnetic spectrum. The PL emission is associated with the order-disorder structural, even small structural changes can modify the interactions between electronic states. The structural disorder results in formation of new energy levels in the forbidden region. The proximity or distance of these new energy levels formed in relation to valence band and to the conduction band results in PL spectra located at higher or lower energies. These interactions change the electronic states which can be influenced by defects, particularly the interface defects between the layers of the thin films. The presence of defects results in changes in the broad band matrix intensity and in displacement of the PL emission maximum. (author)

  15. Advanced Modular, Multi-Channel, High Speed Fiber Optic Sensing System for Acoustic Emissions Monitoring, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to prove the feasibility of innovations based on ultra-light-weight, ultra-high-speed, multi-channel,...

  16. Crystal habit dependent quantum confined photoluminescence of zinc oxide nanostructures

    International Nuclear Information System (INIS)

    Arellano, Ian Harvey J.; Payawan, Leon Jr. M.; Sarmago, Roland V.

    2008-01-01

    Diverse zinc oxide crystal habits namely wire, rods, tubes, whiskers and tetrapods were synthesized via hydrothermal and carbothermal reduction routes. A vapor current induced regionalization in the carbothermal synthesis lead to the isolation of these crystal habits for characterization. The surface morphology of the nanostructures was analyzed via field emission scanning electron microscopy (FESEM). The morphology and crystallinity of the as-synthesized nanostructure architectural motifs were related to their photoluminescence (PL). The photoluminescence at 157 nm was taken using F2 excimer laser and a crystal habit dependent response was observed. X-ray diffraction (XRD) analyses were conducted to deduce the degree of crystallinity showing results consistent with the excitonic emission at the band edge and visible emission at the electron-hole recombination sites. The presence of minimal crystal defects which gave the green emission was supported by energy dispersive spectroscopy (EDS) data. Transmission spectroscopy for the tetrapods exhibited an interesting PL reduction associated with high-energy deep traps in the nanostructures. Furthermore, some intensity dependent characteristics were deduced indicating quantum confined properties of these nano structures. (author)

  17. Synthesis and photoluminescence property of silicon carbide ...

    Indian Academy of Sciences (India)

    Administrator

    The β-SiC nanowires thin films exhibit the strong photoluminescence (PL) peak at a wavelength of. 400 nm, which is significantly ... in the nanowires. Keywords. SiC nanowires; nanocrystalline diamond; crystal growth; photoluminescence. 1. ... unique mechanical, electrical and thermal properties. Due to the wide band gap ...

  18. Preparation and photoluminescence properties of Tm{sup 3+}-doped ZrO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mingli [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Zhao, Jianling, E-mail: hebutzhaoj@126.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Xu, Rongqing [Tianjin Zhonghuan Advanced Material & Technology Co., LTD, Tianjin 300384 (China); Fu, Ning [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Wang, Xixin, E-mail: xixinwang@126.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2016-07-25

    Tm{sup 3+}-doped ZrO{sub 2} nanotube arrays were prepared by anodization of a Zr–Tm alloy (3 at.% Tm) obtained by a powder metallurgical method. The morphologies, structures, elemental valence, and photoluminescence properties were characterized by using scanning electron microscope, X-ray diffractometer, X-ray photoelectron spectrometer and photoluminescence analyser, respectively. Results show that preparing conditions and annealing temperatures have significant effects on the crystalline structure and photoluminescence performance. The sample TmZNT-Org prepared in formamide + glycerol organic solution is mainly monoclinic phase and the sample TmZNT-Aq prepared in aqueous solution is mainly tetragonal phase. The sample TmZNT-Org had the strongest photoluminescence peak when annealed at 800 °C, whereas both TmZNT-Aq samples annealed at 600 °C and 800 °C had the strongest photoluminescence peak. The monoclinic phase was conductive to the emission at 454 nm while the tetragonal phase was conductive to the emission at 460 nm. - Highlights: • Tm{sup 3+}-doped ZrO{sub 2} nanotube arrays were prepared by anodization of a Zr-Tm alloy. • Crystal structure had remarkable effects on the photoluminescence properties. • The monoclinic phase was conductive to the emission at 454 nm. • The tetragonal phase was conductive to the emission at 460 nm.

  19. Photoluminescence of carbon dots from mesoporous silica

    Science.gov (United States)

    Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

    2016-09-01

    Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

  20. SYNTHESIS AND PHOTOLUMINESCENCE STUDIES ON ZINC OXIDE NANOWIRES

    Directory of Open Access Journals (Sweden)

    Nguyen Ngoc Long

    2017-11-01

    Full Text Available Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL and photoluminescence excitation (PLE spectra of the nanowires were measured in the range of temperature from 15 K to the room temperature. Photoluminescence spectra at low temperatures exhibit a group of ultraviolet (UV narrow peaks in the region 368 nm ~ 390 nm, and a blue-green very broad peak at 500 nm. Origin of the emission lines in PL spectra and the lines in PLE spectra is discussed.

  1. Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes.

    Science.gov (United States)

    Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C; Shimoni, Olga; Aharonovich, Igor

    2015-03-21

    Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.

  2. Broadband infrared photoluminescence in silicon nanowires with high density stacking faults.

    Science.gov (United States)

    Li, Yang; Liu, Zhihong; Lu, Xiaoxiang; Su, Zhihua; Wang, Yanan; Liu, Rui; Wang, Dunwei; Jian, Jie; Lee, Joon Hwan; Wang, Haiyan; Yu, Qingkai; Bao, Jiming

    2015-02-07

    Making silicon an efficient light-emitting material is an important goal of silicon photonics. Here we report the observation of broadband sub-bandgap photoluminescence in silicon nanowires with a high density of stacking faults. The photoluminescence becomes stronger and exhibits a blue shift under higher laser powers. The super-linear dependence on excitation intensity indicates a strong competition between radiative and defect-related non-radiative channels, and the spectral blue shift is ascribed to the band filling effect in the heterostructures of wurtzite silicon and cubic silicon created by stacking faults.

  3. Tunable photoluminescence of porous silicon by liquid crystal infiltration

    International Nuclear Information System (INIS)

    Ma Qinglan; Xiong Rui; Huang Yuanming

    2011-01-01

    The photoluminescence (PL) of porous silicon films has been investigated as a function of the amount of liquid crystal molecules that are infiltrated into the constricted geometry of the porous silicon films. A typical nematic liquid crystal 4-pentyl-4'-cyanobiphenyl was employed in our experiment as the filler to modify the PL of porous silicon. It is found that the originally red PL of porous silicon films can be tuned to blue by simply adjusting the amount of liquid crystal molecules in the microchannels of the porous films. The chromaticity coordinates are calculated for the recorded PL spectra. The mechanism of the tunable PL is discussed. Our results have demonstrated that the luminescent properties of porous silicon films can be efficiently tuned by liquid crystal infiltration. - Highlights: → Liquid crystal infiltration can tune the photoluminescence of porous silicon. → Red emission of porous silicon can be switched to blue by the infiltration. → Chromaticity coordinates are calculated for the tuned emissions. → White emission is realized for porous silicon by liquid crystal infiltration.

  4. Photoluminescence properties of PZT 52/48 synthesized by microwave hydrothermal method using PVA with template

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, G.F., E-mail: guilmina@hotmail.com [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil); Gasparotto, G. [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil); Paris, E.C. [Empresa Brasileira de Pesquisa Agropecuaria, Embrapa Instrumentacao, Rua XV de novembro, 1452, Centro, 13.569-970 Sao Carlos, SP (Brazil); Zaghete, M.A.; Longo, E.; Varela, J.A. [Instituto de Quimica, Universidade Estadual Paulista, Departamento de Bioquimica e Tecnologia Quimica, Rua Francisco Degni s/n, Quitandinha, 14800-900 Araraquara, SP (Brazil)

    2012-01-15

    Lead Titanate Zirconate (PZT) perovskite powders were synthesized by microwave hydrothermal method (M-H) at 180 {sup o}C for different time periods (2, 4, 8 and 12 h) with the presence of aqueous polyvinyl alcohol (PVA) solution 0.36 g L{sup -1}. The X-Ray diffraction (XRD), SE-FEG as well as the measurements of photoluminescence (PL) emission were used for monitoring the formation of a perovskite phase with random polycrystalline distortion in the structure. Emission spectra with fixed excitation wavelength of 350 nm showed higher value for the powder obtained after undergoing 8 h of treatment. A theoretical model derived from previous calculations allows us to discuss the origin of photoluminescence emission in the powders, which can be further related to the local disorder in the network of both ZrO{sub 6} and TiO{sub 6} octahedral, and dodecahedral PbO{sub 12}. The new morphology initially observed from the PZT perovskite crystal growth bearing the shape of fine plates is found to be directly related to photoluminescence emission with energy lower than that present in the PZT with cube-like morphology that emits in 560 nm. - Highlights: > This work details the efficiency of microwave hydrothermal synthesis in obtaining PZT powders. > PVA is used as a crystallization agent of PZT particles. > PZT particles presented photoluminescent (PL) behavior. > There aren't previous reports of photoluminescent PZT obtained by microwave hydrothermal synthesis. > Photoluminescence is one more interesting property for technological applications this material.

  5. Photoluminescence of Mg_2Si films fabricated by magnetron sputtering

    International Nuclear Information System (INIS)

    Liao, Yang-Fang; Xie, Quan; Xiao, Qing-Quan; Chen, Qian; Fan, Meng-Hui; Xie, Jing; Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di

    2017-01-01

    Highlights: • High quality Mg_2Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg_2Si films was reported. • The Mg_2Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg_2Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg_2Si-based light-emitting devices, Mg_2Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg_2Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg_2Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg_2Si film on Si (111) displays polycrystalline structure, whereas Mg_2Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg_2Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg_2Si films was observed for the first time. The PL emission wavelengths of Mg_2Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg_2Si films on glass substrate is much larger than that of Mg_2Si film on Si (111) substrate. The activation energy of 18 meV is

  6. Photoluminescence efficiency in AlGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Tamulaitis, G.; Mickevičius, J. [Institute of Applied Research and Semiconductor Physics Department, Vilnius University, Sauletekio av. 9-III, Vilnius LT-10222 (Lithuania); Jurkevičius, J., E-mail: jonas.jurkevicius@ff.vu.lt [Institute of Applied Research and Semiconductor Physics Department, Vilnius University, Sauletekio av. 9-III, Vilnius LT-10222 (Lithuania); Shur, M.S. [Department of ECE and CIE, Rensselaer Polytechnic Institute (United States); Shatalov, M.; Yang, J.; Gaska, R. [Sensor Electronic Technology, Inc. (United States)

    2014-11-15

    Photoluminescence spectroscopy of AlGaN/AlGaN multiple quantum wells under quasi-steady-state conditions in the temperature range from 8 to 300 K revealed a strong dependence of droop onset threshold on temperature that was explained by the influence of carrier delocalization. The delocalization at room temperature results predominantly in enhancement of bimolecular radiative recombination, while being favorable for enhancement of nonradiative recombination at low temperatures. Studies of stimulated emission confirmed the strong influence of carrier localization on droop.

  7. The photoluminescence of Co-Al-layered double hydroxide

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH). It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated. Its excitation spectrum shows a maximum peak near the wavelength 370 nm, the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue. This new optical property will be expected to extend the potential applications of LDHs in optical materials field.

  8. Microscopic modeling of photoluminescence of strongly disordered semiconductors

    International Nuclear Information System (INIS)

    Bozsoki, P.; Kira, M.; Hoyer, W.; Meier, T.; Varga, I.; Thomas, P.; Koch, S.W.

    2007-01-01

    A microscopic theory for the luminescence of ordered semiconductors is modified to describe photoluminescence of strongly disordered semiconductors. The approach includes both diagonal disorder and the many-body Coulomb interaction. As a case study, the light emission of a correlated plasma is investigated numerically for a one-dimensional two-band tight-binding model. The band structure of the underlying ordered system is assumed to correspond to either a direct or an indirect semiconductor. In particular, luminescence and absorption spectra are computed for various levels of disorder and sample temperature to determine thermodynamic relations, the Stokes shift, and the radiative lifetime distribution

  9. Radiation emission at channeling of electrons in a strained layer Si1-xGex undulator crystal

    DEFF Research Database (Denmark)

    Backe, H.; Krambrich, D.; Lauth, W.

    2013-01-01

    ML source. Spectra taken at the beam energy of 270 MeV at channeling in the undulating (110) planes exhibit a broad excess yield around the theoretically expected photon energies of 0.069 MeV, as compared with a flat silicon reference crystal. Model calculations on the basis of synchrotron-like radiation...

  10. A Review of the Synthesis and Photoluminescence Properties of Hybrid ZnO and Carbon Nanomaterials

    Directory of Open Access Journals (Sweden)

    Protima Rauwel

    2016-01-01

    Full Text Available Photoluminescent ZnO carbon nanomaterials are an emerging class of nanomaterials with unique optical properties. They each, ZnO and carbon nanomaterials, have an advantage of being nontoxic and environmentally friendly. Their cost-effective production methods along with simple synthesis routes are also of interest. Moreover, ZnO presents photoluminescence emission in the UV and visible region depending on the synthesis routes, shape, size, deep level, and surface defects. When combined with carbon nanomaterials, modification of surface defects in ZnO allows tuning of these photoluminescence properties to produce, for example, white light. Moreover, efficient energy transfer from the ZnO to carbon nanostructures makes them suitable candidates not only in energy harvesting applications but also in biosensors, photodetectors, and low temperature thermal imaging. This work reviews the synthesis and photoluminescence properties of 3 carbon allotropes: carbon quantum or nanodots, graphene, and carbon nanotubes when hybridized with ZnO nanostructures. Various synthesis routes for the hybrid materials with different morphologies of ZnO are presented. Moreover, differences in photoluminescence emission when combining ZnO with each of the three different allotropes are analysed.

  11. Structure and photoluminescence of the A-Gesub(x)Sesub(1-x) system

    International Nuclear Information System (INIS)

    Kosa Somogyi, I.; Koos, M.

    1982-08-01

    A review of correlations between structural and luminescence properties of Gesub(x)Sesub(1-x) (0< x<0.43) glasses is given. Photoluminescence emission and excitation spectra, fatigue and decay kinetics of luminescence in these compounds are discussed. Existing data and models are compared and discrepancies between predictions of the models and experimental observations are pointed out. (author)

  12. Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings.

    Science.gov (United States)

    Abbarchi, Marco; Cavigli, Lucia; Somaschini, Claudio; Bietti, Sergio; Gurioli, Massimo; Vinattieri, Anna; Sanguinetti, Stefano

    2011-10-31

    A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications.

  13. Optical excitation and external photoluminescence quantum efficiency of Eu3+ in GaN

    NARCIS (Netherlands)

    de Boer, W.D.A.M.; McGonigle, C.; Gregorkiewicz, T.; Fujiwara, Y.; Stallinga, P.

    2014-01-01

    We investigate photoluminescence of Eu-related emission in a GaN host consisting of thin layers grown by organometallic vapor-phase epitaxy. By comparing it with a reference sample of Eu-doped Y2O3, we find that the fraction of Eu3+ ions that can emit light upon optical excitation is of the order of

  14. Origin of Blue-Green Emission in α-Zn2P2O7 and Local Structure of Ln3+ Ion in α-Zn2P2O7:Ln3+ (Ln = Sm, Eu): Time-Resolved Photoluminescence, EXAFS, and DFT Measurements.

    Science.gov (United States)

    Gupta, Santosh Kumar; Ghosh, Partha Sarathi; Yadav, Ashok Kumar; Jha, Shambhu Nath; Bhattacharyya, Dibyendu; Kadam, Ramakant Mahadeo

    2017-01-03

    Considering the fact that pyrophosphate-based hosts are in high demand for making highly efficient luminescence materials, we doped two visible lanthanide ions, viz. Sm 3+ and Eu 3+ , in Zn 2 P 2 O 7 . Interestingly, it was oberved that pure Zn 2 P 2 O 7 displayed blue-green dual emission on irradiation with ultraviolet light. Emission and lifetime spectroscopy shows the presence of defects in pyrophosphate samples which are responsible for such emission. DFT calculations clearly pinpointed that the electronic transitions between defect states located at just below the conduction band minimum (arises due to V O 1+ and V O 2+ defects) and valence band maximum, as well as impurity states situated in the band gap, can lead to dual emission in the blue-green region, as is also indicated by emission and lifetime spectra. X-ray absorption near edge spectroscopy (XANES) shows the stabilization of europium as well as samarium ion in the +3 oxidation state in α-Zn 2 P 2 O 7 . The fact that α-Zn 2 P 2 O 7 has two different coordination numbers for zinc ions, i.e. five- and six-coordinate, the study of dopant ion distribution in this particular matrix will be an important step in realizing a highly efficient europium- and samarium-based red-emitting phosphor. Time resolved photoluminescence (TRPL) shows that both of these ions are heterogeneously distributed between five- and six-coordinated Zn 2+ sites and it is the six-coordinated Zn 2+ site which is the most favorable for lanthanide ion doping. Extended X-ray absorption fine structure (EXAFS) measurements also suggested that a six-coordinated zinc ion is the preferred site occupied by trivalent lanthanide ions, which is in complete agreement with TRPL results. It was observed that there is almost complete transfer of photon energy from Zn 2 P 2 O 7 to Eu 3+ , whereas this transfer is inefficient and almost incomplete in case of Sm 3+ , which is indeed important information for the realization of pyrophosphate

  15. Photoluminescent properties of single crystal diamond microneedles

    Science.gov (United States)

    Malykhin, Sergey A.; Ismagilov, Rinat R.; Tuyakova, Feruza T.; Obraztsova, Ekaterina A.; Fedotov, Pavel V.; Ermakova, Anna; Siyushev, Petr; Katamadze, Konstantin G.; Jelezko, Fedor; Rakovich, Yury P.; Obraztsov, Alexander N.

    2018-01-01

    Single crystal needle-like diamonds shaped as rectangular pyramids were produced by combination of chemical vapor deposition and selective oxidation with dimensions and geometrical characteristics depending on the deposition process parameters. Photoluminescence spectra and their dependencies on wavelength of excitation radiation reveal presence of nitrogen- and silicon-vacancy color centers in the diamond crystallites. Photoluminescence spectra, intensity mapping, and fluorescence lifetime imaging microscopy indicate that silicon-vacancy centers are concentrated at the crystallites apex while nitrogen-vacancy centers are distributed over the whole crystallite. Dependence of the photoluminescence on excitation radiation intensity demonstrates saturation and allows estimation of the color centers density. The combination of structural parameters, geometry and photoluminescent characteristics are prospective for advantageous applications of these diamond crystallites in quantum information processing and optical sensing.

  16. Effect of growth temperature on photoluminescence and piezoelectric characteristics of ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Water, Walter [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Fang, T.-H. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China)], E-mail: fang.tehua@msa.hinet.net; Ji, L.-W.; Lee, C.-C. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China)

    2009-02-25

    ZnO nanowire arrays were synthesized on Au-coated silicon (1 0 0) substrates by using vapour-liquid-solid process in this work. The effect of growth temperatures on the crystal structure and the surface morphology of ZnO nanowires were investigated by X-ray diffraction and scanning electron microscope. The absorption and optical characteristics of the nanowires were examined by Ultraviolet/Visible spectroscopy, and photoluminescence, respectively. The photoluminescence results exhibited ZnO nanowires had an ultraviolet and blue emission at 383 and 492 nm. Then a nanogenerator with ZnO nanowire arrays was fabricated and demonstrated Schottky-like current-voltage characteristics.

  17. Giant Enhancement of Small Photoluminescent Signals on Glass Surfaces Covered by Self-Assembled Silver Nanorings.

    Science.gov (United States)

    Sousanis, A; Poulopoulos, P; Karoutsos, V; Trachylis, D; Politis, C

    2017-02-01

    Self-assembled nanostructures with the shape of nanospheres or nanorings were formed after annealing of ultrathin Ag films grown on glass, in a furnace with air at 460 °C. Intense localized surface plasmon resonances were recorded for these nanostructures with maxima at the green-blue light. The surface became functional in terms of enhancing the weak photoluminescence of glass between 2–400 times. This system provides an easy way of enhancing the photoluminescence emission of initially low performance materials.

  18. Photoluminescence of 1,3-dimethyl pyrazoloquinoline derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Koscien, E. [1st Liceum, Sobieskiego 22, 42-700 Lubliniec (Poland); Gondek, E.; Pokladko, M. [Institute of Physics, Technical University of Krakow, Podhorazych 1, 30-084 Krakow (Poland); Jarosz, B. [Department of Chemistry, Hugon Kollotaj Agricultural University, Al. Mickiewicza 24/28, 30-059 Krakow (Poland); Vlokh, R.O. [Institute of Physical Optics, Dragomanova 23, 79005 Lviv (Ukraine); Kityk, A.V. [Department of Electrical Engineering, Czestochowa University of Technology, Al. Armii Krajowej 17, 42-200 Czestochowa (Poland)], E-mail: kityk@ap.univie.ac.at

    2009-04-15

    This paper presents absorption and photoluminescence of 6-F, 6-Br, 6-Cl, 7-TFM and 6-COOEt derivatives of 1,3-dimethyl-1H-Pyrazolo[3,4-b]quinoline (DMPQ). The measured absorption and emission spectra are compared with the quantum chemical calculations performed by means of the semi-empirical methods (AM1 or PM3) that are applied either to the equilibrium conformations in vacuo (T = 0 K) or combined with the molecular dynamics simulations (T = 300 K). The spectra calculated by the AM1 method appear to be for all dyes in practically excellent agreement with the measured ones. In particular, the position of the first absorption band is obtained with the accuracy up to a few nanometers, whereas the calculated photoluminescence spectra predict the positions of the emission maxima for a gas phase with the accuracy up to 10-18 nm. The photoemission spectra of DMPQ dyes are considerably less solvatochromic comparing to phenyl-containing pyrazoloquinoline derivatives. According to the quantum chemical analysis the reason for such behaviour lies in a local character of the electronic transitions of DMPQ dyes which are characterized by a relatively small difference between the excited state and ground state dipole moments. Importantly that the rotational dynamics of both methyl subunits does not change this situation.

  19. Photoluminescence of acupoint 'Waiqiu' in human superficial fascia

    International Nuclear Information System (INIS)

    Zhang Yuan; Yan Xiaohui; Liu Chenglin; Dang Ruishan; Zhang Xinyi

    2006-01-01

    The spectral characters of an acupuncture point named 'Waiqiu' in superficial fascia tissue have been studied by photoluminescence (PL) spectroscopy under the excitation of 457.9 nm. The PL around 'Waiqiu' acupuncture point consists of two sub-bands resulting from the flavin adenine dinucleotide (FAD) and phospholipids, and the porphyrins (including purine, isoxanthopterin and tryptophan), respectively. More emission due to FAD and phospholipids is found inside the acupuncture effect area of 'Waiqiu' than its marginal or outside acupuncture regions. The ratio of emission intensity of FAD and phospholipids to one of porphyrins gradually decreases along the direction away from the center of the acupuncture point. It implies that the component proportion changes between FAD, phospholipids and porphyrins around the 'Waiqiu' acupuncture point. We suggest that there might be a certain relationship between redox function of FAD and 'Waiqiu' acupuncture effect

  20. Excitation dependence of photoluminescence in silicon quantum dots

    International Nuclear Information System (INIS)

    Wen Xiaoming; Lap Van Dao; Hannaford, Peter; Cho, E-C; Cho, Young H; Green, Martin A

    2007-01-01

    We have studied the optical properties of silicon quantum dots (QDs) embedded in a silicon oxide matrix using photoluminescence (PL) and time-resolved PL. A broad luminescence band is observed in the red region, in which the time evolution exhibits a stretched exponential decay. With increasing excitation intensity a significant saturation effect is observed. Direct electron-hole recombination is the dominant effect in the red band. A relatively narrow peak appears around 1.5 eV, which is attributed to the interface states overlapping with transition from the ground state of the silicon QDs. The saturation factor increases slowly with detection photon energy between 1.5 and 1.8 eV, which is attributed to the emission from zero-phonon electron-hole recombination. At higher photon energies the significantly increased saturation factor suggests a different emission mechanism, most likely the defect states from silicon, silicon oxide or silicon rich oxide

  1. Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes

    Science.gov (United States)

    Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C.; Shimoni, Olga; Aharonovich, Igor

    2015-03-01

    Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07510b

  2. Photoluminescence and photoluminescence excitation studies in 80 MeV Ni ion irradiated MOCVD grown GaN

    Energy Technology Data Exchange (ETDEWEB)

    Devaraju, G. [School of Physics, University of Hyderabad, Central University P.O., Hyderabad 500 046 (India); Pathak, A.P., E-mail: appsp@uohyd.ernet.in [School of Physics, University of Hyderabad, Central University P.O., Hyderabad 500 046 (India); Srinivasa Rao, N.; Saikiran, V. [School of Physics, University of Hyderabad, Central University P.O., Hyderabad 500 046 (India); Enrichi, Francesco [Coordinamento Interuniversitario Veneto per le Nanotecnologie (CIVEN), via delle Industrie 5, Marghera, I-30175Venice (Italy); Trave, Enrico [Dipartimento di Chimica Fisica, Universita Ca' Foscari Venezia, Dorsoduro 2137, I-30123 Venice (Italy)

    2011-09-01

    Highlights: {yields} MOCVD grown GaN samples are irradiated with 80 MeV Ni ions at room temperature. {yields} PL and PLE studies have been carried out for band to band, BL and YL emissions. {yields} Ni ions irradiated GaN shows BL band at 450 nm besides YL band. {yields} Radiation annealed Ga vacancies have quenching effect on YL intensity. {yields} We speculated that BL and YL are associated with N and Ga vacancies, respectively. - Abstract: We report damage creation and annihilation under energetic ion bombardment at a fixed fluence. MOCVD grown GaN thin films were irradiated with 80 MeV Ni ions at a fluence of 1 x 10{sup 13} ions/cm{sup 2}. Irradiated GaN thin films were subjected to rapid thermal annealing for 60 s in nitrogen atmosphere to anneal out the defects. The effects of defects on luminescence were explored with photoluminescence measurements. Room temperature photoluminescence spectra from pristine sample revealed presence of band to band transition besides unwanted yellow luminescence. Irradiated GaN does not show any band to band transition but there is a strong peak at 450 nm which is attributed to ion induced defect blue luminescence. However, irradiated and subsequently annealed samples show improved band to band transitions and a significant decrease in yellow luminescence intensity due to annihilation of defects which were created during irradiation. Irradiation induced effects on yellow and blue emissions are discussed.

  3. Blue photoluminescence in Ti-doped alkaline-earth stannates

    International Nuclear Information System (INIS)

    Yamashita, Takahiro; Ueda, Kazushige

    2007-01-01

    Blue photoluminescence properties of Ti-doped alkaline-earth stannates, A 2 (Sn 1- x Ti x )O 4 (A=Ca, Sr, Ba) (x=0.005-0.15), were examined at room temperature. These stannates showed intense broad emission bands peaking at 445 nm for Ca 2 SnO 4 , at 410 nm for Sr 2 SnO 4 , and at 425 nm for Ba 2 SnO 4 under UV excitation. Emission intensities were relatively insensitive to Ti concentration and no sharp concentration quenching was observed. Mixing alkaline-earth ions in the crystal structures did not increase the emission intensities in the A 2 (Sn 1- x Ti x )O 4 system. The excitation spectra of these stannates exhibited broad bands just below the fundamental absorption edges, implying that luminescence centers do not consist of the component elements in the host materials. It was suggested that the isolated TiO 6 complexes are possible luminescence centers in these materials, as previously proposed in other Ti-doped stannates such as Mg 2 SnO 4 and Y 2 Sn 2 O 7 . - Graphical abstract: Blue photoluminescence properties of Ti-doped alkaline-earth stannates, A 2 (Sn 1- x Ti x )O 4 (A=Ca, Sr, Ba) (x=0.005-0.15), were examined at room temperature. These stannates showed intense broad emission bands peaking at 445 nm for Ca 2 SnO 4 , at 410 nm for Sr 2 SnO 4 , and at 425 nm for Ba 2 SnO 4 under UV excitation

  4. Probing the interlayer coupling of twisted bilayer MoS2 using photoluminescence spectroscopy.

    Science.gov (United States)

    Huang, Shengxi; Ling, Xi; Liang, Liangbo; Kong, Jing; Terrones, Humberto; Meunier, Vincent; Dresselhaus, Mildred S

    2014-10-08

    Two-dimensional molybdenum disulfide (MoS2) is a promising material for optoelectronic devices due to its strong photoluminescence emission. In this work, the photoluminescence of twisted bilayer MoS2 is investigated, revealing a tunability of the interlayer coupling of bilayer MoS2. It is found that the photoluminescence intensity ratio of the trion and exciton reaches its maximum value for the twisted angle 0° or 60°, while for the twisted angle 30° or 90° the situation is the opposite. This is mainly attributed to the change of the trion binding energy. The first-principles density functional theory analysis further confirms the change of the interlayer coupling with the twisted angle, which interprets our experimental results.

  5. Surface States Effect on the Large Photoluminescence Redshift in GaN Nanostructures

    KAUST Repository

    Ben Slimane, Ahmed

    2013-01-01

    We report on the large photoluminescence redshift observed in nanostructures fabricated using n-type GaN by ultraviolet (UV) metal-assisted electroless chemical-etching method. The scanning electron microscopy (SEM) characterization showed nanostructures with size dispersion ranging from 10 to 100 nm. We observed the crystalline structure using high resolution transmission electron microscopy (HRTEM) and electron energy loss (EELS) techniques. In contrast to 362 nm UV emission from the GaN epitaxy, the nanostructures emitted violet visible-light in photoluminescence (PL) characterization with increasing optical excitation. An energy band model was presented to shed light on the large PL redshift under the influence of surface states, which resulted in two competing photoluminescence mechanisms depending on excitation conditions.

  6. Enormous enhancement of ZnO nanorod photoluminescence

    International Nuclear Information System (INIS)

    Wang, Y.H.; Duan, W.J.; Wu, Z.L.; Zheng, D.; Zhou, X.W.; Zhou, B.Y.; Dai, L.J.; Wang, Y.S.

    2012-01-01

    ZnO nanorod arrays were grown on quartz slices in the aqueous solution of zinc acetate and hexamethylenetetramine at 90 °C. Then ZnO:Mg shells were epitaxially grown on the nanorods to form core/shell structures in the aqueous solution of zinc acetate, magnesium acetate and hexamethylenetetramine at the same temperature. Effects of the shells and UV laser beam irradiation on the crystal structure and photoluminescence properties of ZnO nanorods were studied. ZnO:Mg shells suppress the green emission and enhance the UV emission intensity of the nanorods by 38 times. Enhancement of the UV emission depends on the Mg content in the shells. Short time UV laser beam irradiation could improve ZnO nanorod emission efficiently. The UV emission intensity of ZnO nanorods is enhanced by 71 times by capping and subsequent UV laser beam irradiation. - Highlights: ► ZnO nanorod arrays were grown on quartz slices in solution at 90 °C. ► The nanorods were capped by ZnO:Mg layers to form core/shell structures. ► ZnO:MgO shells suppress the green emission and enhance the UV emission intensity by 38 times. ► The enhancement depends on the Mg content in the shells. ► Exposing the nanorods to 325 laser beam improves the UV emission efficiently. ► Capping and 325 nm laser beam irradiation could enhance the nanorod UV emission intensity by 71 times.

  7. Temperature-dependent photoluminescence of water-soluble quantum dots for a bioprobe

    International Nuclear Information System (INIS)

    Liu Tiancai; Huang Zhenli; Wang Haiqiao; Wang Jianhao; Li Xiuqing; Zhao Yuandi; Luo Qingming

    2006-01-01

    The photoluminescence of water-soluble CdSe/ZnS core/shell quantum dots is found to be temperature-dependent: as temperature arising from 280 K to 351 K, the photoluminescence declines with emission peak shifting towards the red at a rate of ∼0.11 nm K -1 . And the studies show that the photoluminescence of water-soluble CdSe/ZnS quantum dots with core capped by a thinner ZnS shell is more sensitive to temperature than that of ones with core capped by a thicker one. That is, with 50% decrement of the quantum yield the temperature of the former need to arise from 280 K to 295 K, while the latter requires much higher temperature (315.6 K), which means that the integrality of shell coverage is a very important factor on temperature-sensitivity to for the photoluminescence of water-soluble CdSe/ZnS quantum dots. Moreover, it is found that the water-soluble CdSe quantum dots with different core sizes, whose cores are capped by thicker ZnS shells, possess almost the same sensitivity to the temperature. All of the studies about photoluminescence temperature-dependence of water-soluble CdSe/ZnS core/shell quantum dots show an indispensable proof for their applications in life science

  8. Temperature-dependent photoluminescence of water-soluble quantum dots for a bioprobe

    Energy Technology Data Exchange (ETDEWEB)

    Liu Tiancai [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Huang Zhenli [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang Haiqiao [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang Jianhao [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li Xiuqing [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zhao Yuandi [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)]. E-mail: zydi@mail.hust.edu.cn; Luo Qingming [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2006-02-10

    The photoluminescence of water-soluble CdSe/ZnS core/shell quantum dots is found to be temperature-dependent: as temperature arising from 280 K to 351 K, the photoluminescence declines with emission peak shifting towards the red at a rate of {approx}0.11 nm K{sup -1}. And the studies show that the photoluminescence of water-soluble CdSe/ZnS quantum dots with core capped by a thinner ZnS shell is more sensitive to temperature than that of ones with core capped by a thicker one. That is, with 50% decrement of the quantum yield the temperature of the former need to arise from 280 K to 295 K, while the latter requires much higher temperature (315.6 K), which means that the integrality of shell coverage is a very important factor on temperature-sensitivity to for the photoluminescence of water-soluble CdSe/ZnS quantum dots. Moreover, it is found that the water-soluble CdSe quantum dots with different core sizes, whose cores are capped by thicker ZnS shells, possess almost the same sensitivity to the temperature. All of the studies about photoluminescence temperature-dependence of water-soluble CdSe/ZnS core/shell quantum dots show an indispensable proof for their applications in life science.

  9. Time-resolved photoluminescence measurements of InP/ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Pham Thi Thuy; Ung Thi Dieu Thuy; Tran Thi Kim Chi; Le Quang Phuong; Nguyen Quang Liem [Institute of Materials Science, VAST, 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Li Liang; Reiss, Peter [CEA Grenoble, DSM/INAC/SPrAM (UMR 5819 CEA-CNRS-Universite Joseph Fourier)/LEMOH, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)], E-mail: liemnq@ims.vast.ac.vn

    2009-09-01

    This paper reports the results on the time-resolved photoluminescence study of InP/ZnS core/shell quantum dots. The ZnS shell played a decisive role to passivate imperfections on the surface of InP quantum dots, consequently giving rise to a strong enhancement of the photoluminescence from the InP core. Under appropriate excitation conditions, not only the emission from the InP core but also that from the ZnS shell was observed. The emission peak in InP core quantum dots varied as a function of quantum dots size, ranging in the 600 - 700 nm region; while the ZnS shell showed emission in the blue region around 470 nm, which is interpreted as resulting from defects in ZnS.

  10. Photoluminescence and radiation response properties of Ce3+-doped CsCaCl3 crystalline scintillator

    International Nuclear Information System (INIS)

    Fujimoto, Yutaka; Saeki, Keiichiro; Tanaka, Hironori; Yahaba, Takuma; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki

    2016-01-01

    In this paper, we report on the photoluminescence and scintillation properties of a newly developed CsCaCl 3 :Ce (0.5 mol%) crystalline scintillator grown by the vertical Bridgman method. The fluorescence quantum efficiency for the Ce 3+ characteristic emission bands centered at around 350–400 nm was 76% under excitation at 330 nm light. The photoluminescence decay time of the Ce 3+ was approximately 32 ns. When x-ray excited the crystal, intense emission bands were observed at 350–400 nm, and could be attributed to the Ce 3+ emission. The scintillation light yield of the developed crystal was ∼7600 ph MeV −1 compared to a NaI:Tl commercial scintillator, and the principal scintillation decay time was approximately 340 ns plus two fast components of around 1.6 ns and 45 ns. (paper)

  11. Study of defect generated visible photoluminescence in zinc oxide nano-particles prepared using PVA templates

    Energy Technology Data Exchange (ETDEWEB)

    Oudhia, A. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Choudhary, A., E-mail: aarti.bhilai@gmail.com [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Sharma, S.; Aggrawal, S. [Department of Physics, Government V.Y.T. PG. Autonomous College, Durg, 491001 C.G. (India); Dhoble, S.J. [RTM University Nagpur, Maharashtra (India)

    2014-10-15

    Intrinsic defect generated photoluminescence (PL) in zinc oxide nanoparticles (NPs) obtained by a PVA template based wet-chemical process has been studied. A good controllability was achieved on the surface defects, structure and the morphology of ZnO NPs through the variation of solvents used in synthesis. The PL emission strongly depended on the defect structure and morphology. SEM, XRD, annealing and PL excitation studies were used to analyze the types of defects involved in the visible emission as well as the defect concentration. The mechanism for the blue, green and yellow emissions was proposed. The spectral content of the visible emission was controlled through generation/removal of defects through the shape transformation or annealing by focusing on defect origins and broad controls. - Highlights: • ZnO nanoparticles were synthesized using poly-vinyl alcohol template in various solvents. • The structure and morphology of ZnO nanoparticles were depended on dielectric constant and boiling point of solvents. • Photoluminescence properties of ZnO nanoparticles were studied. • Maximum optical absorbance and Photoluminescence intensity were found in ethanolic preparation. • ZnO nanoparticles were annealed at different temperatures for detection of defect emission.

  12. Biological Particle Emissions From a South-East Asian Tropical Rainforest Using a Real- Time Dual Channel UV Fluorescence Bio-Aerosol Spectrometer

    Science.gov (United States)

    Gabey, A.; Coe, H.; Gallagher, M.; McFiggans, G.; Kaye, P.; Stanley, W.; Foot, V.

    2008-12-01

    and net emission for all fungal spores is ~1 μ g m-3 and ~50 Tg yr-1. These calculations demonstrate the potential importance of PBA, and in particular fungal spores, for global budgets of organic aerosols, particularly in tropical regions, however uncertainties are extremely large, ranging from 50 - 1000 Tg yr- 1. In this study we use the WIBS-3: a low-cost portable single-particle dual-channel UV fluorescence spectrometer (Kaye et al., 2008) to investigate the dynamics of PBA in real-time within and above a tropical forest of 50 m height in Borneo, Malaysia, to estimate net PBA emissions. Different circadian cycles were observed for bio and non-bio aerosol sources and the factors controlling bioaerosol emissions will be discussed in detail.

  13. Synthesis, characterization, photoluminescence and thermally ...

    Indian Academy of Sciences (India)

    Administrator

    X-ray diffraction and scanning electron microscopy to identify the crystalline phase and determine the parti- cle size. ... Spectral characteristics of the TSL glow showed emission around 565, 599 and. 641 nm, indicating ... thesis and characterization of rare-earth-doped ZnAl2O4 ..... Other researchers have reported similar.

  14. Effect of additionally introduced Zn and Eu dopants on the photoluminescence spectra of Er-doped GaN crystals

    International Nuclear Information System (INIS)

    Mezdrogina, M.M.; Krivolapchuk, V.V.; Petrov, V.N.; Rodin, S.N.; Cherenkov, A.V.

    2006-01-01

    It is shown that the effect of dopants on the photoluminescence spectrum depends on the conductivity type of the initial GaN crystals. The sensitizing effect of emission is observed in wurtzite p-GaN crystals doped with Er. The same effect was previously observed in such crystals doped with Eu and Zn. In n-type GaN crystals sequentially doped with Eu, Zn, and Er, the emission is observed in visible and infrared ranges of the photoluminescence spectrum [ru

  15. Photoluminescence properties of Li{sup +}-doped KNbO{sub 3}: Eu{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnaiah, R.; Kim, Dongwoo; Yi, Soungsoo; Kim, Sunghoon [Silla University, Busan (Korea, Republic of); Jang, Kiwan; Lee, Hosueb [Changwon National University, Changwon (Korea, Republic of); Moon, Byungkee; Jeong, Junghyun [Pukyong National University, Busan (Korea, Republic of)

    2010-12-15

    Different concentrations of Li{sup +}-ions doped KNbO{sub 3}:Eu polycrystalline powder phosphors were prepared by using the conventional solid state reaction method and were characterized by using X-ray diffraction, field emission scanning electron microscopy, and by using photoluminescence excitation and emission measurements. The morphological and the photoluminescence properties of the phosphors were effectively improved with Li-doping. The PL properties as a function of Li concentration in the Li-doped KNbO{sub 3}:Eu phosphors using different excitation wavelengths, along with a comparison of results with these in similar reported works, are discussed in the present work.

  16. Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with metal-phenolic networks

    OpenAIRE

    Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C.; Shimoni, Olga; Aharonovich, Igor

    2015-01-01

    Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and biolabeling. In this work we demonstrate a robust approach to surface functionalize individual nanodiamonds with metal-phenolic networks that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation suppr...

  17. Photoluminescence properties of carbazole compounds

    International Nuclear Information System (INIS)

    Qu Yufeng; Xu Liang; Sun Lianlai; Cao Linhong; Fang Yu; Zhang Qingjun; Luo Xuan; Liu Hongjie; Huang Jin; Jiang Xiaodong

    2013-01-01

    Poly[bis(6-carbazolhexyloxy)]phosphazene with good thermal stability(about 290 ℃) and a low glass transition temperature(about 36 ℃) was synthesized with N-(6-hydroxyhexyl)carbazole and linear polydichlorophosphazene. Steady state fluorescence spectra elucidated that the maximum fluorescence-emission wavelengths of carbazole, N-(6-hydroxyhexyl)carbazole and poly[bis(6-carbazolhexyloxy)]phosphazene are 420, 410, and 393 nm, respectively. The fluorescence intensity of N-(6-hydroxyhexyl)carbazole and poly[bis(6-carbazolhexyloxy)]phosphazene decreases orderly and has a blue-shift compared with carbazole. The transient fluorescence spectra show that the linear backbone and the isolated dπ-pπ hybrid orbital of polyphosphazene might increase steric hindrance and disrupt the previous conjugate system, leading to decrease of the fluorescence lifetime of poly[bis(6-carbazolhexyloxy)]phosphazene at several emission wavelengths. (authors)

  18. Photoluminescence and dynamics of excitation relaxation in graphene oxide-porphyrin nanorods composite

    International Nuclear Information System (INIS)

    Khenfouch, M.; Wéry, J.; Baïtoul, M.; Maaza, M.

    2014-01-01

    Generally, porphyrin nanostructured materials are known by playing many roles such as photoconductors, photovoltaics and capable of light induced charging. Also their combination with acceptors like graphene, the rising two dimension material, added exciting physical and chemical properties. In this work, Morphology, optical absorption and photoluminescence properties were investigated in order to elucidate the interaction between the few layered graphene oxide (FGO) and pophyrin nanorods. Reporting on the photoluminescence (PL) of both porphyrin nanorods and FGO/porphyrin nanorods composite, synthesized via a self-assembly method, we have experimentally demonstrated the generation of a new photoluminescence band giving rise to a white light. This luminescence was studied by the analysis of its origins and dynamics which show a huge change of exciton life time found to be longer after the interaction with graphene oxide (GO) sheets. -- Highlights: • We prepared FGO-porphyrin nanorods composite via a simple chemical method. • Luminescence properties were studied presenting the absorption, photoluminescence and dynamics measurements. • These results show the emission of a white light which we studied its emissions origins. • TEM images show FGO sheets decorated with porphyrin nanorods. • FGO had like effect an increase of the exciton lifetime in porphyrin nanorods

  19. Giant photoluminescence enhancement in tungsten-diselenide–gold plasmonic hybrid structures

    KAUST Repository

    Wang, Zhuo

    2016-05-06

    Impressive properties arise from the atomically thin nature of transition metal dichalcogenide two-dimensional materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices. Typical photoluminescence enhancement from transition metal dichalcogenides is 100-fold, with recent enhancement of 1,000-fold achieved by simultaneously enhancing absorption, emission and directionality of the system. By suspending WSe2 flakes onto sub-20-nm-wide trenches in gold substrate, we report a giant photoluminescence enhancement of ~20,000-fold. It is attributed to an enhanced absorption of the pump laser due to the lateral gap plasmons confined in the trenches and the enhanced Purcell factor by the plasmonic nanostructure. This work demonstrates the feasibility of giant photoluminescence enhancement in WSe2 with judiciously designed plasmonic nanostructures and paves a way towards the implementation of plasmon-enhanced transition metal dichalcogenide photodetectors, sensors and emitters.

  20. Plasmon-assisted photoluminescence enhancement of SiC nanocrystals by proximal silver nanoparticles

    International Nuclear Information System (INIS)

    Zhang, N.; Dai, D.J.; Fan, J.Y.

    2012-01-01

    Highlights: ► We studied metal surface plasmon-enhanced photoluminescence in SiC nanocrystals. ► The integrated emission intensity can be enhanced by 17 times. ► The coupling between SiC emission and Ag plasmon oscillation induces the enhancement. ► The enhancement is tunable with varied spacing thickness of electrolytes. - Abstract: Plasmon-enhanced photoluminescence has wide application potential in many areas, whereas the underlying mechanism is still in debate. We report the photoluminescence enhancement in SiC nanocrystal–Ag nanoparticle coupled system spaced by the poly(styrene sulfonic acid) sodium salt/poly(allylamine hydrochloride) polyelectrolyte bilayers. The integrated luminescence intensity can be improved by up to 17 times. Our analysis indicates that the strong coupling between the SiC nanocrystals and the surface plasmon oscillation of the silver nanoparticles is the major cause of the luminescence enhancement. These findings will help to understand the photoluminescence enhancement mechanism as well as widen the applications of the SiC nanocrystals in photonics and life sciences.

  1. Influence of acetylcholinesterase immobilization on the photoluminescence properties of mesoporous silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, Muhammad [Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701 (Korea, Republic of); Rafiq, Muhammad; Seo, Sung-Yum [Department of Biology, Kongju National University, Gongju, Chungnam 314-701 (Korea, Republic of); Lee, Ki Hwan, E-mail: khlee@kongju.ac.kr [Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701 (Korea, Republic of)

    2014-07-01

    Acetylcholinesterase immobilized p-type porous silicon surface was prepared by covalent attachment. The immobilization procedure was based on support surface chemical oxidation, silanization, surface activation with cyanuric chloride and finally covalent attachment of free enzyme on the cyanuric chloride activated porous silicon surface. Different pore diameter of porous silicon samples were prepared by electrochemical etching in HF based electrolyte solution and appropriate sample was selected suitable for enzyme immobilization with maximum trapping ability. The surface modification was studied through field emission scanning electron microscope, EDS, FT-IR analysis, and photoluminescence measurement by utilizing the fluctuation in the photoluminescence of virgin and enzyme immobilized porous silicon surface. Porous silicon showed strong photoluminescence with maximum emission at 643 nm and immobilization of acetylcholinesterase on porous silicon surface cause considerable increment on the photoluminescence of porous silicon material while acetylcholinesterase free counterpart did not exhibit any fluorescence in the range of 635–670 nm. The activities of the free and immobilized enzymes were evaluated by spectrophotometric method by using neostigmine methylsulfate as standard enzyme inhibitor. The immobilized enzyme exhibited considerable response toward neostigmine methylsulfate in a dose dependent manner comparable with that of its free counterpart alongside enhanced stability, easy separation from the reaction media and significant saving of enzyme. It was believed that immobilized enzyme can be exploited in organic and biomolecule synthesis possessing technical and economical prestige over free enzyme and prominence of easy separation from the reaction mixture.

  2. Giant photoluminescence enhancement in tungsten-diselenide–gold plasmonic hybrid structures

    KAUST Repository

    Wang, Zhuo; Dong, Zhaogang; Gu, Yinghong; Chang, Yung-Huang; Zhang, Lei; Li, Lain-Jong; Zhao, Weijie; Eda, Goki; Zhang, Wenjing; Grinblat, Gustavo; Maier, Stefan A.; Yang, Joel K. W.; Qiu, Cheng-Wei; Wee, Andrew T. S.

    2016-01-01

    Impressive properties arise from the atomically thin nature of transition metal dichalcogenide two-dimensional materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices. Typical photoluminescence enhancement from transition metal dichalcogenides is 100-fold, with recent enhancement of 1,000-fold achieved by simultaneously enhancing absorption, emission and directionality of the system. By suspending WSe2 flakes onto sub-20-nm-wide trenches in gold substrate, we report a giant photoluminescence enhancement of ~20,000-fold. It is attributed to an enhanced absorption of the pump laser due to the lateral gap plasmons confined in the trenches and the enhanced Purcell factor by the plasmonic nanostructure. This work demonstrates the feasibility of giant photoluminescence enhancement in WSe2 with judiciously designed plasmonic nanostructures and paves a way towards the implementation of plasmon-enhanced transition metal dichalcogenide photodetectors, sensors and emitters.

  3. Influence of acetylcholinesterase immobilization on the photoluminescence properties of mesoporous silicon surface

    International Nuclear Information System (INIS)

    Saleem, Muhammad; Rafiq, Muhammad; Seo, Sung-Yum; Lee, Ki Hwan

    2014-01-01

    Acetylcholinesterase immobilized p-type porous silicon surface was prepared by covalent attachment. The immobilization procedure was based on support surface chemical oxidation, silanization, surface activation with cyanuric chloride and finally covalent attachment of free enzyme on the cyanuric chloride activated porous silicon surface. Different pore diameter of porous silicon samples were prepared by electrochemical etching in HF based electrolyte solution and appropriate sample was selected suitable for enzyme immobilization with maximum trapping ability. The surface modification was studied through field emission scanning electron microscope, EDS, FT-IR analysis, and photoluminescence measurement by utilizing the fluctuation in the photoluminescence of virgin and enzyme immobilized porous silicon surface. Porous silicon showed strong photoluminescence with maximum emission at 643 nm and immobilization of acetylcholinesterase on porous silicon surface cause considerable increment on the photoluminescence of porous silicon material while acetylcholinesterase free counterpart did not exhibit any fluorescence in the range of 635–670 nm. The activities of the free and immobilized enzymes were evaluated by spectrophotometric method by using neostigmine methylsulfate as standard enzyme inhibitor. The immobilized enzyme exhibited considerable response toward neostigmine methylsulfate in a dose dependent manner comparable with that of its free counterpart alongside enhanced stability, easy separation from the reaction media and significant saving of enzyme. It was believed that immobilized enzyme can be exploited in organic and biomolecule synthesis possessing technical and economical prestige over free enzyme and prominence of easy separation from the reaction mixture.

  4. Photoluminescence and dynamics of excitation relaxation in graphene oxide-porphyrin nanorods composite

    Energy Technology Data Exchange (ETDEWEB)

    Khenfouch, M., E-mail: khenfouch@yahoo.fr [University Sidi Mohamed Ben Abdellah, Faculty of Sciences Dhar el Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, BP 1796 Atlas, Fez 30 000 (Morocco); iThemba LABS-National Research Foundation of South Africa, Old Faure Road, PO Box 722, Somerset West 7129, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Wéry, J. [Institut des Matériaux Jean Rouxel, Nantes, 2 rue de la Houssinière, BP 32229, 44322 Nantes, Cedex 3 (France); Baïtoul, M., E-mail: baitoul@yahoo.fr [University Sidi Mohamed Ben Abdellah, Faculty of Sciences Dhar el Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, BP 1796 Atlas, Fez 30 000 (Morocco); Maaza, M. [iThemba LABS-National Research Foundation of South Africa, Old Faure Road, PO Box 722, Somerset West 7129, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa)

    2014-01-15

    Generally, porphyrin nanostructured materials are known by playing many roles such as photoconductors, photovoltaics and capable of light induced charging. Also their combination with acceptors like graphene, the rising two dimension material, added exciting physical and chemical properties. In this work, Morphology, optical absorption and photoluminescence properties were investigated in order to elucidate the interaction between the few layered graphene oxide (FGO) and pophyrin nanorods. Reporting on the photoluminescence (PL) of both porphyrin nanorods and FGO/porphyrin nanorods composite, synthesized via a self-assembly method, we have experimentally demonstrated the generation of a new photoluminescence band giving rise to a white light. This luminescence was studied by the analysis of its origins and dynamics which show a huge change of exciton life time found to be longer after the interaction with graphene oxide (GO) sheets. -- Highlights: • We prepared FGO-porphyrin nanorods composite via a simple chemical method. • Luminescence properties were studied presenting the absorption, photoluminescence and dynamics measurements. • These results show the emission of a white light which we studied its emissions origins. • TEM images show FGO sheets decorated with porphyrin nanorods. • FGO had like effect an increase of the exciton lifetime in porphyrin nanorods.

  5. Enhancement of porous silicon photoluminescence by electroless deposition of nickel

    Energy Technology Data Exchange (ETDEWEB)

    Amdouni, S. [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Rahmani, M., E-mail: rahmanimehdi79@yahoo.com [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Zaïbi, M.-A [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Ecole Nationale Supérieure des Ingénieurs de Tunis, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); Oueslati, M. [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia)

    2015-01-15

    Nickel-porous silicon nanocomposites (PS/Ni) are elaborated by an electroless deposition method using NiCl{sub 2} aqueous solution. The presence of nickel ions in the porous layer is confirmed by Fourier Transformed InfraRed spectroscopy (FTIR) and Raman spectroscopy. The photoluminescence (PL) spectra of PS/Ni, prepared at different electroless durations (t{sub edp}), are analyzed. A remarkable enhancement in the integrated PL intensity of PS containing nickel was observed. The lower t{sub edp} favor the deposition of nickel in PS, hence the silicon dangling bonds at the porous surface are quenched and this was increased the PL intensity. However, for the longer t{sub edp}, the PL intensity has been considerably decreased due to the destruction of some Si nanocrystallites. The PL spectra of PS/Ni, for t{sub edp} less than 8 min, show a multiband profile indicating the creation of new luminescent centers by Ni elements which induces a strong modification in the emission mechanisms. - Highlights: • Deposition of Ni ions into porous silicon (PS) layer using the electroless method. • Formation of Ni–O bonds on the porous layer. • The photoluminescence (PL) intensity of PS is enhanced after Ni deposition. • The increase of the PL is due to the contribution of radiative centers related to Ni.

  6. Green–white electroluminescence and green photoluminescence of zinc complexes

    Energy Technology Data Exchange (ETDEWEB)

    Janghouri, Mohammad; Mohajerani, Ezeddin [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran 1983963113 (Iran, Islamic Republic of); Amini, Mostafa M.; Najafi, Ezzatollah [Department of Chemistry, Shahid Beheshti University, G.C., Tehran 1983963113 (Iran, Islamic Republic of)

    2014-10-15

    A series of zinc complexes has been synthesized and utilized as fluorescent materials in organic light-emitting diodes (OLEDs). All prepared complexes were characterized by elemental analysis (CHN), UV–vis, FT-IR and {sup 1}H NMR spectroscopy. The energy levels of zinc complexes were determined by cyclic voltammetry measurements. Devices with fundamental structure of ITO/PVK:PBD (50 nm)/zinc complexes/BCP (5 nm)/Alq{sub 3} (25 nm)/Al (180 nm) were fabricated. A green electroluminescence was obtained from thin film complexes at 25 nm thickness. When thickness of the complex bis(2-methylquinolin-8-olato)-bis[(acetato)-(methanol)zinc(II)] (B) in thin film decreased from 25 nm to 20, 18, and 12 nm, a white electroluminescence obtained. The white emission which was composed of blue and green attributed to the PVK:PBD blend and thickness of complex, respectively. With 12 nm thickness of complex, a maximum luminance of 4530 cd/m{sup 2} at a current density 398.32 mA/cm{sup 2} with CIE coordinates of 0.22 and 0.36 at 20 V was achieved. - Highlights: • Several new zinc complexes have been synthesized and utilized as fluorescent materials in OLEDs. • Photoluminescence emission of zinc complexes showed a red shift in respect to PVK:PBD blend. • Green electroluminescence emission from zinc complexes was achieved. • White emission has been obtained for an OLED by changing thickness of the zinc complex.

  7. Green–white electroluminescence and green photoluminescence of zinc complexes

    International Nuclear Information System (INIS)

    Janghouri, Mohammad; Mohajerani, Ezeddin; Amini, Mostafa M.; Najafi, Ezzatollah

    2014-01-01

    A series of zinc complexes has been synthesized and utilized as fluorescent materials in organic light-emitting diodes (OLEDs). All prepared complexes were characterized by elemental analysis (CHN), UV–vis, FT-IR and 1 H NMR spectroscopy. The energy levels of zinc complexes were determined by cyclic voltammetry measurements. Devices with fundamental structure of ITO/PVK:PBD (50 nm)/zinc complexes/BCP (5 nm)/Alq 3 (25 nm)/Al (180 nm) were fabricated. A green electroluminescence was obtained from thin film complexes at 25 nm thickness. When thickness of the complex bis(2-methylquinolin-8-olato)-bis[(acetato)-(methanol)zinc(II)] (B) in thin film decreased from 25 nm to 20, 18, and 12 nm, a white electroluminescence obtained. The white emission which was composed of blue and green attributed to the PVK:PBD blend and thickness of complex, respectively. With 12 nm thickness of complex, a maximum luminance of 4530 cd/m 2 at a current density 398.32 mA/cm 2 with CIE coordinates of 0.22 and 0.36 at 20 V was achieved. - Highlights: • Several new zinc complexes have been synthesized and utilized as fluorescent materials in OLEDs. • Photoluminescence emission of zinc complexes showed a red shift in respect to PVK:PBD blend. • Green electroluminescence emission from zinc complexes was achieved. • White emission has been obtained for an OLED by changing thickness of the zinc complex

  8. White light photoluminescence from ZnS films on porous Si substrates

    International Nuclear Information System (INIS)

    Wang Caifeng; Li Weibing; Li Qingshan; Hu Bo

    2010-01-01

    ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique. White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated. (semiconductor materials)

  9. SEMICONDUCTOR MATERIALS: White light photoluminescence from ZnS films on porous Si substrates

    Science.gov (United States)

    Caifeng, Wang; Qingshan, Li; Bo, Hu; Weibing, Li

    2010-03-01

    ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique. White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.

  10. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    Directory of Open Access Journals (Sweden)

    Tamar Andelman

    2007-01-01

    Full Text Available A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm nanorods were synthesized from trihexylamine, and large diameter (50–80 nm nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green emission of the photoluminescence (PL spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  11. Photoluminescence in Spray Pyrolysis Deposited β-In2S3 Thin Films

    Science.gov (United States)

    Jayakrishnan, R.

    2018-04-01

    Spray pyrolysis deposited In2S3 thin films exhibit two prominent photoluminescent emissions. One of the emissions is green in color and centered at around ˜ 540 nm and the other is centered at around ˜ 690 nm and is red in color. The intensity of the green emission decreases when the films are subjected to annealing in air or vacuum. The intensity of red emission increases when films are air annealed and decreases when vacuum annealed. Vacuum annealing leads to an increase in work function whereas air annealing leads to a decrease in work function for this thin film system relative to the as deposited films indicating changes in space charge regions. Surface photovoltage analysis using a Kelvin probe leads to the conclusion that inversion of band bending occurs as a result of annealing. Correlating surface contact potential measurements using a Kelvin probe, x-ray photoelectron spectroscopy and photoluminescence, we conclude that the surface passivation plays a critical role in controlling the photoluminescence from the spray pyrolysis deposited for In2S3 thin films.

  12. Dilute nitride InNP quantum dots: Growth and photoluminescence mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Takabayashi, K.; Kamiya, I. [Quantum Interface Laboratory, Toyota Technological Institute, Nagoya 468-8511 (Japan); Sukrittanon, S. [Material Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Pan, J. L.; Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-10-27

    Self-assembled dilute nitride InNP quantum dots (QDs) in GaP matrix grown under the Stranski-Krastanov mode by gas-source molecular beam epitaxy are studied. The N-related localized states inside the InNP QDs provide a spatially direct recombination channel, in contrast to the spatially indirect channel through the strained In(N)P QDs/GaP interface states. The N incorporation into InP QDs therefore causes a blueshift and double-peak features in photoluminescence, which are not observed in other dilute nitride materials.

  13. Gold nanoparticles: BSA (Bovine Serum Albumin) coating and X-ray irradiation produce variable-spectrum photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kuo-Hao [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Lai, Sheng-Feng [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Yan-Cheng; Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Ong, Edwin B.L. [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Tan, Hui-Ru [Institute of Materials Research and Engineering, 3 Research Link, 117602 (Singapore); Tok, Eng Soon [Physics Department, National University of Singapore, 117542 (Singapore); Yang, C.S. [Center for Nanomedicine, National Health Research Institutes, Miaoli 350, Taiwan (China); Margaritondo, G. [Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Hwu, Y., E-mail: phhwu@sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan (China)

    2015-01-15

    We show that by using different x-ray irradiation times of BSA-coated Au nanoparticles (NPs) we can change their ultraviolet-stimulated photoluminescence and shift the spectral weight over the visible spectral range. This is due to the interplay of two emission bands, one due to BSA and the other related to gold. The emission properties did not change with time over a period of several months. - Highlights: • Gold nanoparticles (Au NPs) coated with Bovine Serum Albumin (BSA) are synthesized by x-ray irradiation. • BSA coated AuNPs with ∼1 nm size show strong photoluminescence in red by UV excitation. • The blue photoluminescence of BSA increase with x-ray irradiation. • Increase x-ray irradiation time during the synthesis shift the color of the colloid from red to blue.

  14. Gold nanoparticles: BSA (Bovine Serum Albumin) coating and X-ray irradiation produce variable-spectrum photoluminescence

    International Nuclear Information System (INIS)

    Lee, Kuo-Hao; Lai, Sheng-Feng; Lin, Yan-Cheng; Chou, Wu-Ching; Ong, Edwin B.L.; Tan, Hui-Ru; Tok, Eng Soon; Yang, C.S.; Margaritondo, G.; Hwu, Y.

    2015-01-01

    We show that by using different x-ray irradiation times of BSA-coated Au nanoparticles (NPs) we can change their ultraviolet-stimulated photoluminescence and shift the spectral weight over the visible spectral range. This is due to the interplay of two emission bands, one due to BSA and the other related to gold. The emission properties did not change with time over a period of several months. - Highlights: • Gold nanoparticles (Au NPs) coated with Bovine Serum Albumin (BSA) are synthesized by x-ray irradiation. • BSA coated AuNPs with ∼1 nm size show strong photoluminescence in red by UV excitation. • The blue photoluminescence of BSA increase with x-ray irradiation. • Increase x-ray irradiation time during the synthesis shift the color of the colloid from red to blue

  15. Blue-green photoluminescence in MCM-41 mesoporous nanotubes

    CERN Document Server

    Shen, J L; Lui, Y L; Cheng, P W; Cheng, C F

    2003-01-01

    Different photoluminescence (PL) techniques have been used to study the blue-green emission from siliceous MCM-41 nanotubes. It was found that the intensity of the blue-green PL is enhanced by rapid thermal annealing (RTA). This enhancement is explained by the generation of twofold-coordinated Si centres and non-bridging oxygen hole centres, in line with the surface properties of MCM-41. On the basis of the analysis of the PL following RTA, polarized PL, and PL excitation, we suggest that the triplet-to-singlet transition of twofold-coordinated silicon centres is responsible for the blue-green PL in MCM-41 nanotubes. (letter to the editor)

  16. Ultraviolet photoluminescence in Gd-doped silica and phosphosilicate fibers

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2017-04-01

    Full Text Available Optical fiber lasers operating in the near infrared and visible spectral regions have relied on the spectroscopic properties of rare earth ions such as Yb3+, Er3+, Tm3+, Nd3+, and Sm3+. Here, we investigate Gd3+ doping in phosphosilicate and pure silica fibers using solution doping and sol-gel techniques, respectively, for potential applications in the ultraviolet. Photoluminescence spectra for optical fiber bundles and fiber preforms were recorded and compared. Emissions at 312 nm (phosphosilicate and 314 nm (pure silica were observed when pumping to the Gd3+ 6DJ, 6IJ, and 6PJ = 5/2, 3/2 energy levels. Oxygen deficient center was observed in solution doping sample with a wide absorption band centered at around 248 nm not affecting pumping to 6IJ states.

  17. Growth orientation dependent photoluminescence of GaAsN alloys

    International Nuclear Information System (INIS)

    Han, Xiuxun; Tanaka, Tomohiro; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi; Sato, Shinichiro

    2012-01-01

    We report photoluminescence (PL) studies of both as-grown and electron-irradiated GaAsN epilayers on (311)A/B and (100) GaAs substrates. A long room-temperature (RT) PL lifetime, as well as an enhanced N incorporation, is observed in (311)B GaAsN epilayers as compared with (311)A and (100) samples. There is no direct correlation between the RT PL lifetime and the emission intensity from Ga vacancy complex detected at low temperature. The lifetime damage coefficient is relatively low for (311)B GaAsN. The irradiation-induced nonradiative recombination defects are suggested to be N- and/or As-related according to a geometrical analysis based on the tetrahedral coordination of GaAsN crystal.

  18. Preparation, characterization and photoluminescence of nanocrystalline calcium molybdate

    International Nuclear Information System (INIS)

    Phuruangrat, Anukorn; Thongtem, Titipun; Thongtem, Somchai

    2009-01-01

    Nanocrystalline calcium molybdate was successfully synthesized from Ca(NO 3 ) 2 and Na 2 MoO 4 in ethylene glycol using a microwave radiation method. Body-centered tetragonal structured calcium molybdate with narrow nanosized distribution was detected using XRD, SAED and TEM. A diffraction pattern was also simulated and was found to be in accordance with those obtained from the experiment and JCPDS standard. Raman and FTIR spectra show the Mo-O prominent stretching bands in the [MoO 4 ] 2- tetrahedrons at 879.59 and 743-895 cm -1 , respectively. Photoluminescence emission of CaMoO 4 was detected at 477 nm, caused by the annihilation of a self-trapped excitons from the [MoO 4 ] 2- excited complex.

  19. Photoluminescence studies on porous silicon/polymer heterostructure

    International Nuclear Information System (INIS)

    Mishra, J.K.; Bhunia, S.; Banerjee, S.; Banerji, P.

    2008-01-01

    Hybrid devices formed by filling porous silicon with MEH-PPV or poly [2-methoxy-5(2-ethylhexyloxy-p-phenylenevinylene)] have been investigated in this work. Analyses of the structures by scanning electron microscopy (SEM) demonstrated that the porous silicon layer was filled by the polymer with no significant change of the structures except that the polymer was infiltrated in the pores. The photoluminescence (PL) of the structures at 300 K showed that the emission intensity was very high as compared with that of the MEH-PPV films on different substrates such as crystalline silicon (c-Si) and indium tin oxide (ITO). The PL peak in the MEH-PPV/porous silicon composite structure is found to be shifted towards higher energy in comparison with porous silicon PL. A number of possibilities are discussed to explain the observations

  20. Detection of Human Ig G Using Photoluminescent Porous Silicon Interferometer.

    Science.gov (United States)

    Cho, Bomin; Kim, Seongwoong; Woo, Hee-Gweon; Kim, Sungsoo; Sohn, Honglae

    2015-02-01

    Photoluminescent porous silicon (PSi) interferometers having dual optical properties, both Fabry-Pérot fringe and photolumincence (PL), have been developed and used as biosensors for detection of Human Immunoglobin G (Ig G). PSi samples were prepared by electrochemical etching of p-type silicon under white light exposure. The surface of PSi was characterized using a cold field emission scanning electron microscope. The sensor system studied consisted of a single layer of porous silicon modified with Protein A. The system was probed with various fragments of aqueous human immunoglobin G (Ig G) analyte. Both reflectivity and PL were simultaneously measured under the exposure of human Ig G. An increase of optical thickness and decrease of PL were obtained under the exposure of human Ig G. Detection limit of 500 fM was observed for the human Ig G.

  1. Phase evolution and photoluminescence enhancement of CePO4 nanowires from a low phosphate concentration system

    International Nuclear Information System (INIS)

    Xu Pengfei; Yu Ranbo; Zong Lingbo; Wang Jiali; Wang Dan; Deng Jinxia; Chen Jun; Xing Xianran

    2013-01-01

    Uniform CePO 4 nanowires have been successfully synthesized in a low phosphate concentration system through a single-step hydrothermal process. The low phosphate concentration might decrease the surface PO 4 3− adsorption of the as-synthesized CePO 4 nanowires efficiently and benefit their photoluminescence. The CePO 4 nanowires were identified to go through phase evolution from pure monoclinic to mixed hexagonal and monoclinic phase by only increasing the initial molar ratio of cerium and phosphate source (denoted as Ce/P). Interestingly, the strongest photoluminescence was observed in the CePO 4 nanowires synthesized with the initial Ce/P of 4:1, which proved to be the critical phase evolution point between the hexagonal and monoclinic CePO 4 . Therefore, the strong photoluminescence could be explained by the existence of the structure-sensitive energy level in the CePO 4 . This kind of photoluminescence enhancement would be a meaningful reference for design of other photoluminescent materials, in which the photoluminescent emission might be related to the structure-sensitive energy level. Additionally, the growth processes of CePO 4 nanowires based on related well-designed experiments were proposed.

  2. Photoluminescence, trap states and thermoluminescence decay ...

    Indian Academy of Sciences (India)

    Administrator

    Photoluminescence, trap states and thermoluminescence decay process study of Ca2MgSi2O7 : Eu. 2+. , Dy. 3+ phosphor. RAVI SHRIVASTAVA*, JAGJEET KAUR, VIKAS DUBEY and BEENA JAYKUMAR. Govt. VYT PG Autonomous College, Durg 491 001, (C.G.) India. MS received 9 July 2013; revised 5 December 2013.

  3. Microwave Assisted Synthesis and Photoluminescence Properties of ...

    Indian Academy of Sciences (India)

    46

    earth doping of ZnS would not lead to sufficiently bright PL materials. As a result, several new ... photoluminescence characteristics of ZnS nanoparticles doped with Pb2+. New luminescent ..... Papers, San Francisco, CA, USA, 249. [6] Tanaka ...

  4. Dewetting-Induced Photoluminescent Enhancement of Poly(lauryl methacrylate)/Quantum Dot Thin Films.

    Science.gov (United States)

    Geldmeier, Jeffrey; Rile, Lexy; Yoon, Young Jun; Jung, Jaehan; Lin, Zhiqun; Tsukruk, Vladimir V

    2017-12-19

    A new method for enhancing photoluminescence from quantum dot (QD)/polymer nanocomposite films is proposed. Poly(lauryl methacrylate) (PLMA) thin films containing embedded QDs are intentionally allowed to undergo dewetting on substrates by exposure to a nonsolvent vapor. After controlled dewetting, films exhibited typical dewetting morphologies with increased amounts of scattering that served to outcouple photoluminescence from the film and reduce internal light propagation within the film. Up to a 5-fold enhancement of the film emission was achieved depending on material factors such as the initial film thickness and QD concentration within the film. An increase in initial film thickness was shown to increase the dewetted maximum feature size and its characteristic length until a critical thickness was reached where dewetting became inhibited. A unique light exposure-based photopatterning method is also presented for the creation of high contrast emissive patterns as guided by spatially controlled dewetting.

  5. Physico-chemical mechanism for the vapors sensitivity of photoluminescent InP quantum dots

    Science.gov (United States)

    Prosposito, P.; De Angelis, R.; De Matteis, F.; Hatami, F.; Masselink, W. T.; Zhang, H.; Casalboni, M.

    2016-03-01

    InP/InGaP surface quantum dots are interesting materials for optical chemical sensors since they present an intense emission at room temperature, whose intensity changes rapidly and reversibly depending on the composition of the environmental atmosphere. We present here their emission properties by time resolved photoluminescence spectroscopy investigation and we discuss the physico-chemical mechanism behind their sensitivity to the surrounding atmosphere. Photoluminescence transients in inert atmosphere (N2) and in solvent vapours of methanol, clorophorm, acetone and water were measured. The presence of vapors of clorophorm, acetone and water showed a very weak effect on the transient times, while an increase of up to 15% of the decay time was observed for methanol vapour exposure. On the basis of the vapor molecule nature (polarity, proticity, steric hindrance, etc.) and of the interaction of the vapor molecules with the quantum dots surface a sensing mechanism involving quantum dots non-radiative surface states is proposed.

  6. Physico-chemical mechanism for the vapors sensitivity of photoluminescent InP quantum dots

    International Nuclear Information System (INIS)

    Prosposito, P.; De Angelis, R.; De Matteis, F.; Casalboni, M.; Hatami, F.; Masselink, W.T.; Zhang, H.

    2016-01-01

    InP/InGaP surface quantum dots are interesting materials for optical chemical sensors since they present an intense emission at room temperature, whose intensity changes rapidly and reversibly depending on the composition of the environmental atmosphere. We present here their emission properties by time resolved photoluminescence spectroscopy investigation and we discuss the physico-chemical mechanism behind their sensitivity to the surrounding atmosphere. Photoluminescence transients in inert atmosphere (N 2 ) and in solvent vapours of methanol, chloroform, acetone and water were measured. The presence of vapors of chloroform, acetone and water showed a very weak effect on the transient times, while an increase of up to 15% of the decay time was observed for methanol vapour exposure. On the basis of the vapor molecule nature (polarity, proticity, steric hindrance, etc.) and of the interaction of the vapor molecules with the quantum dots surface a sensing mechanism involving quantum dots non-radiative surface states is proposed. (paper)

  7. Reversible photoluminescence in spiropyran-modified porous silicon

    International Nuclear Information System (INIS)

    Lee, Chen-Yu; Hu, Chih-Hsuan; Cheng, Sheng-Lin; Chu, Chih-Chien; Hsiao, Vincent K.S.

    2015-01-01

    Spiropyran-modified porous silicon (spiro-PS) was used for the first time as an organic–inorganic hybrid material by using reversible photoluminescence (PL). Before spiropyran modification, the peak wavelength from PS was approximately 600 nm. Subsequent spiropyran modification strongly quenched the PL intensity, from 15,000 to 2000 counts. However, under UV light irradiation, the PL intensity from spiro-PS was increased gradually to 20,000 counts because of the photoinduced ring opening from a colorless spiropyran (SP-form) to a colored merocyanine (MC-form). Furthermore, the resulting peak wavelength of the PL of an MC–PS sample red-shifted from 600 to 650 nm, and the PL intensity was higher than that of unmodified PS. Because the fluorescence emission band (500–700 nm) of PS substantially overlapped the absorption band (500–700 nm) of the MC-form of spiropyran, the energy transfer from the PS (donor) to the open-ring-state MC-form (acceptor) occurs efficiently. The intensity of the PL from spiro-PS can be reversibly modulated using a heat stimulus. The current demonstrations have potential in reversible solid-state lighting or data storage applications. - Highlights: • Spiropyran-modified porous silicon (spiro-PS) was used for the first time as an organic–inorganic hybrid material with reversible photoluminescence (PL). • UV light irradiation make PL intensity from spiro-PS increased due to the photo-induced ring opening process. • The energy transfer from the PS (donor) to the open-ring state of spiropyran (acceptor) was to be efficient due to the fluorescence emission band of PS substantially overlapped with the absorption band of the ring-opened spiro. • The intensity of the PL from spiro-PS can be reversibly modulated using a heat stimulus

  8. Tilted dipole model for bias-dependent photoluminescence pattern

    Energy Technology Data Exchange (ETDEWEB)

    Fujieda, Ichiro, E-mail: fujieda@se.ritsumei.ac.jp; Suzuki, Daisuke; Masuda, Taishi [Department of Electrical and Electronic Engineering, Ritsumeikan University, Kusatsu 525-8577 (Japan)

    2014-12-14

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission.

  9. Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

    International Nuclear Information System (INIS)

    Xu, Jing; Hu, Chenguo; Xi, Yi; Peng, Chen; Wan, Buyong; He, Xiaoshan

    2011-01-01

    Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: → In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. → The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. → The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10 -3 emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10 -3 emu/g. → The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V 2 O 5 and BaCl 2 at 200 o C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba 3 V 2 O 8 with small amount of Ba 3 VO 4.8 coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of ∼20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO 4 tetrahedron with T d symmetry in Ba 3 V 2 O 8 . The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10 -3 emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10 -3 emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.

  10. Photoluminescence and absorption spectra of various common TL phosphors - interpretation of TL mechanisms

    International Nuclear Information System (INIS)

    Nagpal, J.S.

    1980-01-01

    Photoluminescence and absorption spectra of TL phosphors TLD-100, CaF 2 :Dy, CaSO 4 :Dy(0.05%wt), CaSO 4 :Tm(0.05%wt) and Mg 2 SiO 4 :Tb have been measured. The absorption spectra are typical of RE 2+ in rare earth doped irradiated phosphors. On heating RE 2+ yields RE 3+ and emission from the excited states of RE 3+ is observed. (author)

  11. Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

    Science.gov (United States)

    Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

    2013-08-01

    A novel metal organic framework (MOF) formulated as [Eu(H2O)2(fdc)(ox)0.5·(H2O)]n (1, fdc2-=2,5-furandicarboxylate, ox2-=oxalate), was hydrothermally synthesized via in situ ox2- generation from the partial decomposition of the fdc2- ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H2O, ox2-and fdc2-) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu3+ red emission and the differences observed reflects the slightly different structures of these polymorphs.

  12. Formation Mechanism of Carbogenic Nanoparticles with Dual Photoluminescence Emission

    KAUST Repository

    Krysmann, Marta J.; Kelarakis, Antonios; Dallas, Panagiotis; Giannelis, Emmanuel P.

    2012-01-01

    pyrolysis temperatures while the carbogenic core starts forming at higher temperatures, the PL behavior of CNPs strongly depends on the conditions used for their synthesis. © 2011 American Chemical Society.

  13. In situ enhancement of the blue photoluminescence of colloidal Ga2O3 nanocrystals by promotion of defect formation in reducing conditions.

    Science.gov (United States)

    Wang, Ting; Radovanovic, Pavle V

    2011-07-07

    We demonstrate redox control of defect-based photoluminescence efficiency of colloidal γ-Ga(2)O(3) nanocrystals. Reducing environment leads to an increase in photoluminescence intensity by enhancing the concentration of oxygen vacancies, while the blue emission is suppressed in oxidative conditions. These results enable optimization of nanocrystal properties by in situ defect manipulation. This journal is © The Royal Society of Chemistry 2011

  14. Preparation and photoluminescence properties of Mn2+-activated M2Si5N8 (M = Ca, Sr, Ba) phosphors

    NARCIS (Netherlands)

    Duan, C.J.; Otten, W.M.; Delsing, A.C.A.; Hintzen, H.T.J.M.

    2008-01-01

    Mn2+-doped M2Si5N8 (M=Ca, Sr, Ba) phosphors have been prepared by a solid-state reaction method at high temperature and their photoluminescence properties were investigated. The Mn2+-activated M2Si5N8 phosphors exhibit narrow emission bands in the wavelength range of 500–700 nm with peak center at

  15. Modulation of the photoluminescence in carbon dots through surface modification: from mechanism to white light-emitting diodes

    Science.gov (United States)

    Zhu, Jinyang; Shao, He; Bai, Xue; Zhai, Yue; Zhu, Yongsheng; Chen, Xu; Pan, Gencai; Dong, Biao; Xu, Lin; Zhang, Hanzhuang; Song, Hongwei

    2018-06-01

    Carbon dots (CDs) have emerged as a new type of fluorescent material because of their unique optical advantages, such as high photoluminescence quantum yields (QYs), excellent photo-stability, excitation-dependent emissions, and low toxicity. However, the photoluminescence mechanism for CDs remains unclear, which limits their further practical application. Here, CDs were synthesized via a solvothermal route from citric acid and urea. Through the oxidation and reduction treatment of pristine CDs, the origin of the photoluminescence and the involved mechanism were revealed. We found that the blue/green/red emissions originated from three diverse emitting states, i.e. the intrinsic state, and C=O- and C=N-related surface states, respectively. Based on the as-prepared CDs, a pH sensor depending on the radiometric luminescence detection was developed. Furthermore, we constructed CD/PVP (PVP, polyvinylpyrrolidone) composite films, which exhibited white light emission with photoluminescence QYs of 15.3%. The white light emission with different correlated color temperatures (CCTs), from 4807 K to 3319 K, was obtained by simply changing the amount of PVP solution. Benefiting from the white light-emitting solid-state films, single-component white light-emitting diodes were fabricated with an average color rendering index value (Ra) of 80.0, luminous efficiency of 10.2 lm W‑1, and good working stability, thus indicating a promising potential for practical lighting applications.

  16. Photoluminescent ZnO Nanoparticles and Their Biological Applications

    Directory of Open Access Journals (Sweden)

    Zheng-Yong Zhang

    2015-05-01

    Full Text Available During the past decades, numerous achievements concerning luminescent zinc oxide nanoparticles (ZnO NPs have been reported due to their improved luminescence and good biocompatibility. The photoluminescence of ZnO NPs usually contains two parts, the exciton-related ultraviolet (UV emission and the defect-related visible emission. With respect to the visible emission, many routes have been developed to synthesize and functionalize ZnO NPs for the applications in detecting metal ions and biomolecules, biological fluorescence imaging, nonlinear multiphoton imaging, and fluorescence lifetime imaging. As the biological applications of ZnO NPs develop rapidly, the toxicity of ZnO NPs has attracted more and more attention because ZnO can produce the reactive oxygen species (ROS and release Zn2+ ions. Just as a coin has two sides, both the drug delivery and the antibacterial effects of ZnO NPs become attractive at the same time. Hence, in this review, we will focus on the progress in the synthetic methods, luminescent properties, and biological applications of ZnO NPs.

  17. Angle-resolved photoluminescence spectrum of a uniform phosphor layer

    Science.gov (United States)

    Fujieda, Ichiro; Ohta, Masamichi

    2017-10-01

    A photoluminescence spectrum depends on an emission angle due to self-absorption in a phosphor material. Assuming isotropic initial emission and Lambert-Beer's law, we have derived simple expressions for the angle-resolved spectra emerging from the top and bottom surfaces of a uniform phosphor layer. The transmittance of an excitation light through the phosphor layer can be regarded as a design parameter. For a strongly-absorbing phosphor layer, the forward flux is less intense and more red-shifted than the backward flux. The red-shift is enhanced as the emission direction deviates away from the plane normal. When we increase the transmittance, the backward flux decreases monotonically. The forward flux peaks at a certain transmittance value. The two fluxes become similar to each other for a weakly-absorbing phosphor layer. We have observed these behaviors in experiment. In a practical application, self-absorption decreases the efficiency of conversion and results in angle-dependent variations in chromaticity coordinates. A patterned phosphor layer with a secondary optical element such as a remote reflector alleviates these problems.

  18. Controlled fabrication and tunable photoluminescence properties of Mn2+ doped graphene–ZnO composite

    International Nuclear Information System (INIS)

    Luan, Xinglong; Zhang, Yihe; Tong, Wangshu; Shang, Jiwu; An, Qi; Huang, Hongwei

    2014-01-01

    Highlights: • Graphene–ZnO composites were synthesized by a mixed solvothermal method. • ZnO quantum dots are distributed uniformly on the graphene sheets. • A possible hypothesis is raised for the influence of graphene oxide on the nucleation of ZnO. • Mn 2+ doped graphene–ZnO composites were fabricated and the emission spectra can be tuned by doping. - Abstract: Graphene–ZnO composites (G–ZnO) with controlled morphology and photoluminescence property were synthesized by a mixed solvothermal method. Mixed solvent were composed by dimethyl sulfoxide and ethylene glycol. Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectra were used to characterize G–ZnO. Graphene as a substrate can help the distribution and the dispersity of ZnO, and a possible model of the interaction between graphene oxide and ZnO particles is proposed. At the same time, graphene also reduce the size of ZnO particles to about 5 nm. Furthermore, Mn 2+ ions dopes G–ZnO successfully by the mixed solvothermal synthesis and the doping of Mn 2+ makes G–ZnO shift red from 465 nm to 548 nm and 554 nm in the emission spectrum. The changes of the emission spectrum by the adding of Mn 2+ make G–ZnO have tunable photoluminescence spectrum which is desirable for practical applications

  19. Pressure dependence of photoluminescence of InAs/InP self-assembled quantum wires

    International Nuclear Information System (INIS)

    Ruiz-Castillo, M.; Segura, A.; Sans, J.A.; Martinez-Pastor, J.; Fuster, D.; Gonzalez, Y.; Gonzalez, L.

    2007-01-01

    This paper investigates the electronic structure of self-assembled InAs quantum wires (QWrs), grown under different conditions by molecular beam epitaxy on InP, by means of photoluminescence measurements under pressure. In samples with regularly distributed QWrs, room pressure photoluminescence spectra consist of a broad band centred at about 0.85 eV, which can be easily de-convoluted in a few Gaussian peaks. In samples with isolated QWrs, photoluminescence spectra exhibit up to four clearly resolved bands. Applying hydrostatic pressure, the whole emission band monotonously shifts towards higher photon energies with pressure coefficients ranging from 72 to 98 meV/GPa. In contrast to InAs quantum dots on GaAs, quantum wires photoluminescence is observed up to 10 GPa, indicating that InAs QWrs are metastable well above pressure at which bulk InAs undergoes a phase transition to the rock-salt phase (7 GPa). (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Graphitic carbon nitride/graphene oxide/reduced graphene oxide nanocomposites for photoluminescence and photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrzak, Malgorzata, E-mail: malgorzata.aleksandrzak@o2.pl; Kukulka, Wojciech; Mijowska, Ewa

    2017-03-15

    Highlights: • Graphitic carbon nitride modified with graphene nanostructures. • Influence of graphene nanostructures size in photocatalytic properties of g-C{sub 3}N{sub 4}. • Improved photocatalysis resulted from up-converted photoluminescence. - Abstract: The study presents a modification of graphitic carbon nitride (g-C{sub 3}N{sub 4}) with graphene oxide (GO) and reduced graphene oxide (rGO) and investigation of photoluminescent and photocatalytic properties. The influence of GO and rGO lateral sizes used for the modification was investigated. The nanomaterials were characterized with atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV–vis spectroscopy (DR-UV-vis) and photoluminescence spectroscopy (PL). PL revealed that pristine graphitic carbon nitride and its nanocomposites with GO and rGO emitted up-converted photoluminescence (UCPL) which could contribute to the improvement of photocatalytic activity of the materials. The photoactivity was evaluated in a process of phenol decomposition under visible light. A hybrid composed of rGO nanoparticles (rGONPs, 4–135 nm) exhibited the highest photoactivity compared to rGO with size of 150 nm–7.2 μm and graphene oxide with the corresponding sizes. The possible reason of the superior photocatalytic activity is the most enhanced UCPL of rGONPs, contributing to the emission of light with higher energy than the incident light, resulting in improved photogeneration of electron-hole pairs.

  1. Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

    Science.gov (United States)

    Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

    2015-02-01

    In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Photoluminescence of Turkish purple jade (turkiyenite)

    International Nuclear Information System (INIS)

    Hatipoğlu, Murat; Başevirgen, Yasemin

    2012-01-01

    The purple-colored unique gem material is only found in the Harmancık (Bursa) region of the western Anatolia (Turkey). Therefore, it is specially called “Turkish purple jade or turkiyenite” on the worldwide gem market. Even though its jadeite implication is the principal constituent, the material cannot be considered as a single jadeite mineral since other implications are quartz, orthoclase, epidote, chloritoid and phlogopite minerals. Even if the analytical methods are used to characterize and identify the Turkish purple jade samples in detail, the luminescence spectra, especially photoluminescence features regarding to composite mineral implications of the material are important because of the existence the numerous characteristic broad and intensive luminescence bands in the samples. We can state that the UV-irradiation luminescence centers as photoluminescence (PL) are due to the overall signals in the Turkish purple jade samples. Accordingly, the distinctive photoluminescence peaks at 743, 717, 698, 484, 465 and 442 nm in PL-2D (counter diagram and sections) and PL-3D (sequence spectra) ranging between 300 and 900 nm of wavelengths, and between 220 and 340 K of temperatures are observed. Finally, photoluminescence features of the heterogeneous-structured material cannot be simply attributed to any chemical impurities, since the jade mass has numerous heterogeneous mineral constituents instead of a single jadeite mineral. Six different mineral implications and chemical impurities in the material composition display complex and individual all kind of luminescence features. Therefore, photoluminescence as well as radioluminescence, cathodoluminescence and thermoluminescence spectra provide positive identification regarding to the provenance (geographic origin) of the original Turkish purple jade (turkiyenite). - Highlights: ► The purple-colored gem material is only found in the Harmancık-Bursa region of Turkey. ► Material is called “Turkish purple

  3. Sensitivity of Satellite-Based Skin Temperature to Different Surface Emissivity and NWP Reanalysis Sources Demonstrated Using a Single-Channel, Viewing-Angle-Corrected Retrieval Algorithm

    Science.gov (United States)

    Scarino, B. R.; Minnis, P.; Yost, C. R.; Chee, T.; Palikonda, R.

    2015-12-01

    Single-channel algorithms for satellite thermal-infrared- (TIR-) derived land and sea surface skin temperature (LST and SST) are advantageous in that they can be easily applied to a variety of satellite sensors. They can also accommodate decade-spanning instrument series, particularly for periods when split-window capabilities are not available. However, the benefit of one unified retrieval methodology for all sensors comes at the cost of critical sensitivity to surface emissivity (ɛs) and atmospheric transmittance estimation. It has been demonstrated that as little as 0.01 variance in ɛs can amount to more than a 0.5-K adjustment in retrieved LST values. Atmospheric transmittance requires calculations that employ vertical profiles of temperature and humidity from numerical weather prediction (NWP) models. Selection of a given NWP model can significantly affect LST and SST agreement relative to their respective validation sources. Thus, it is necessary to understand the accuracies of the retrievals for various NWP models to ensure the best LST/SST retrievals. The sensitivities of the single-channel retrievals to surface emittance and NWP profiles are investigated using NASA Langley historic land and ocean clear-sky skin temperature (Ts) values derived from high-resolution 11-μm TIR brightness temperature measured from geostationary satellites (GEOSat) and Advanced Very High Resolution Radiometers (AVHRR). It is shown that mean GEOSat-derived, anisotropy-corrected LST can vary by up to ±0.8 K depending on whether CERES or MODIS ɛs sources are used. Furthermore, the use of either NOAA Global Forecast System (GFS) or NASA Goddard Modern-Era Retrospective Analysis for Research and Applications (MERRA) for the radiative transfer model initial atmospheric state can account for more than 0.5-K variation in mean Ts. The results are compared to measurements from the Surface Radiation Budget Network (SURFRAD), an Atmospheric Radiation Measurement (ARM) Program ground

  4. Optical properties of ion-implanted InP and GaAs: Selectivity-excited photoluminescence spectra

    International Nuclear Information System (INIS)

    Makita, Yunosuke; Yamada, Akimasa; Kimura, Shinji; Niki, Shigeru; Yoshinaga, Hiroshi; Matsumori, Tokue; Iida, Tsutomu; Uekusa, Ichiro

    1993-01-01

    Implantation of Mg+ ions was carried out into high purity InP grown by liquid encapsulated Czochralski method. Mg+ ion-implanted InP presented the formation of plural novel emissions with increasing Mg concentration, [Mg] in the low temperature photoluminescence spectra. Selectively-excited photoluminescence (SPL) measurements were made to examine the features of two-hole replicas pertinent to the emissions of excitons bound to neutral Mg and residual Zn acceptors. Systematic variation of the emission intensities from the two types of two-hole replicas was found to be utilized for the evaluation of ion-implanted materials. The significant discrepancy of emission spectra between PL and SPL was attributed to the difference of the depth examined by using the excitation light with high and low absorption coefficient. The results revealed that the diffusion of ion-implanted Mg is extremely enhanced when [Mg] exceeds 1x10 17 cm -3

  5. Photoluminescence and lasing properties of ZnO nanorods

    International Nuclear Information System (INIS)

    Lee, Geon Joon; Lee, Young Pak; Min, Sun Ki; Han, Sung Hwan; Lim, Hwan Hong; Cha, Myoung Sik; Kim, Sung Soo; Cheong, Hyeon Sik

    2010-01-01

    In this study, we investigated the structures, photoluminescence (PL), and lasing characteristics of the ZnO nanorods prepared by using chemical bath deposition. The continuous-wave HeCd laser excited PL spectra of the ZnO nanorods exhibited two emission bands, one in the UV region and the other in the visible region. The UV emission band has its peak at 3.25 eV with a bandwidth of 160 meV. However, the PL spectra under 355-nm, 35-ps pulse excitation exhibited a spectrally-narrowed UV emission band with a peak at 3.20 eV and a spectral width of 35 meV. The lasing phenomena were ascribed to the amplified spontaneous emission (ASE) caused by coupling of the microcavity effect of ZnO nanorods and the high-intensity excitation. Above the lasing threshold, the ASE peak intensity exhibited a superlinear dependence on the excitation intensity. For an excitation pulse energy of 3 mJ, the ASE peak intensity was increased by enlarging the length of the ZnO nanorods from 1 μm to 4 μm. In addition, the PL spectrum under 800-nm femtosecond pulse excitation exhibited second harmonic generation, as well as the multiphoton absorption-induced UV emission band. In this research, ZnO nanorods were grown on seed layers by using chemical bath deposition in an aqueous solution of Zn(NO 3 ) 2 and hexamethyltetramine. The seed layers were prepared on conducting glass substrates by dip coating in an aqueous colloidal dispersion containing 50% 70-nm ZnO nanoparticles. Scanning electron microscopy clearly revealed that ZnO nanorods were successfully grown on the seed layers.

  6. Shine red and yellow photoluminescence in GdAlO3−δ powders

    International Nuclear Information System (INIS)

    Dhahri, Kh.; Bejar, M.; Dhahri, E.; Soares, M.J.; Sousa, M.; Valente, M.A.

    2015-01-01

    Highlights: • GdAlO 3−δ (δ = 0.0, 0.1 and 0.2) powders were synthesized using the conventional solid-state method. • The PL study has revealed the apparition of intense red and yellow photoluminescence (PL) emissions at room temperature. • The red emission was directly related to the singly ionized oxygen vacancy V O · . • The green emission was directly related the doubly ionized oxygen vacancy V O ·· . • The presence of the singly ionized oxygen vacancy was confirmed from the EPR study. - Abstract: GdAlO 3−δ (δ = 0.0, 0.1 and 0.2) compounds were prepared by the conventional solid-state method. XRD patterns revealed that all samples present a major orthorhombic structure. An intense red and a yellow photoluminescence (PL) emissions were observed at room temperature for δ = 0.0 and δ ≠ 0.0 samples, respectively. The red emission was related to the singly ionized oxygen vacancies V O · . The production of doubly ionized oxygen vacancies V O ·· lead to the appearance of a yellow color observed directly from δ = 0.1 and 0.2 samples. The presence of singly and doubly ionized clusters was found to play an important role in the formation of hole–electron pairs and to give rise to the PL emission. The presence of singly ionized oxygen vacancies was confirmed by the EPR study

  7. Assembling photoluminescent tri(8-quinolinolato)aluminum into periodic mesoporous organosilicas.

    Science.gov (United States)

    Yang, Ying; Zhang, Xin; Kan, Qiubin

    2013-12-01

    Mesostructured and mesoporous materials are emerging as a new class of optical materials. However, their synthesis is nontrivial. In this work, periodic mesostructured metal complex-containing silicas of MCM- and SBA-type bearing homogeneously distributed photoluminescent tri(8-quinolinolato)aluminum inside the channel walls (denoted as Alq3@PMO-MCM and Alq3@PMO-SBA, respectively) have been achieved via one-pot co-assembling of inorganic/surfactant/optically active species. A comprehensive multianalytical characterization of the structural and optical properties demonstrates that both Alq3@PMO-MCM and Alq3@PMO-SBA series gainfully combine the photoluminescent properties of Alq3 with the porous features of PMOs. Regularly arranged pores provide high surface area to disperse optically active components well and render Alq3-containing PMOs promising materials for optoelectronic applications. Copyright © 2013. Published by Elsevier Inc.

  8. Photoluminescence lineshape of ZnO

    Directory of Open Access Journals (Sweden)

    Bruno Ullrich

    2014-12-01

    Full Text Available The merger of the absorption coefficient dispersion, retrieved from transmission by the modified Urbach rule introduced by Ullrich and Bouchenaki [Jpn. J. Appl. Phys. 30, L1285, 1991], with the extended Roosbroeck-Shockley relation reveals that the optical absorption in ZnO distinctively determines the photoluminescence lineshape. Additionally, the ab initio principles employed enable the accurate determination of the carrier lifetime without further specific probing techniques.

  9. Engineering of the photoluminescence of ZnO nanowires by different growth and annealing environments

    DEFF Research Database (Denmark)

    Fernandes Cauduro, André Luis; Sombrio, C I L; Franzen, P L

    2015-01-01

    Optical properties of ZnO nanowires were investigated through photoluminescence (PL) at room and low temperatures. An excitonic structure was observed in the UV band emission and we are able to distinguish between free excitons, bound excitons and donor acceptor pairs. The PL spectra shows deep...... level emissions ranging from 1.4 eV up to 2.8 eV, strongly depending on surface defects whereas the red emission (1.7 eV) is activated at cryogenic temperatures. We attribute the green luminescence (2.4 eV) emission to the presence of zinc vacancies into ZnO nanowires. Further evidences that confirm...... the mechanism are observed in the PL emission spectra after annealing in O2 or Ar environments....

  10. Photoluminescence characteristics of Pb-doped, molecular-beam-epitaxy grown ZnSe crystal layers

    International Nuclear Information System (INIS)

    Mita, Yoh; Kuronuma, Ryoichi; Inoue, Masanori; Sasaki, Shoichiro; Miyamoto, Yoshinobu

    2004-01-01

    The characteristic green photoluminescence emission and related phenomena in Pb-doped, molecular-beam-epitaxy (MBE)-grown ZnSe crystal layers were investigated to explore the nature of the center responsible for the green emission. The intensity of the green emission showed a distinct nonlinear dependence on excitation intensity. Pb-diffused polycrystalline ZnSe was similarly examined for comparison. The characteristic green emission has been observed only in MBE-grown ZnSe crystal layers with moderate Pb doping. The results of the investigations on the growth conditions, luminescence, and related properties of the ZnSe crystal layers suggest that the green emission is due to isolated Pb replacing Zn and surrounded with regular ZnSe lattice with a high perfection

  11. Photoluminescence and pressure effects in short period InN/nGaN superlattices

    DEFF Research Database (Denmark)

    Staszczak, G.; Gorczyca, I.; Suski, T.

    2013-01-01

    Measurements of photoluminescence and its dependence on hydrostatic pressure are performed on a set of InN/nGaN superlattices with one InN monolayer and with different numbers of GaN monolayers. The emission energies, EPL, measured at ambient pressure, are close to the value of the band gap, Eg......, in bulk GaN, in agreement with other experimental findings. The pressure dependence of the emission energies, dEPL/dp, however, resembles that of the InN energy gap. Further, the magnitudes of both EPL and dEPL/dp are significantly higher than those obtained from ab-initio calculations for 1In...

  12. Photoluminescence and magnetophotoluminescence studies in GaInNAs/GaAs quantum wells

    Science.gov (United States)

    Segura, J.; Garro, N.; Cantarero, A.; Miguel-Sánchez, J.; Guzmán, A.; Hierro, A.

    2007-04-01

    We investigate the effects of electron and hole localization in the emission of a GaInNAs/GaAs single quantum well at low temperatures. Photoluminescence measurements varying the excitation density and under magnetic fields up to 14 T have been carried out. The results indicate that electrons are strongly localized in these systems due to small fluctuations in the nitrogen content of the quaternary alloy. The low linear diamagnetic shift of the emission points out the weakness of the Coulomb correlation between electrons and holes and suggests an additional partial localization of the holes.

  13. Red–yellow electroluminescence, yellow–green photoluminescence of novel N, O donor ligands–chelated zirconium (IV) complexes

    International Nuclear Information System (INIS)

    Shahroosvand, Hashem; Nasouti, Fahimeh; Mohajerani, Ezeddin; Khabbazi, Amir

    2013-01-01

    In this paper, eight new zirconium complexes with 1,2,4,5-benzenetetracarboxylic acid (H 4 btec), 1,10-phenanthroline (phen) and 4,7-diphenyl–1,10-phenanthroline (Bphen), were prepared and used as light emitting material in fabricated OLEDs. The structures of these complexes were characterized by UV–vis, FT-IR spectroscopy, 1 H-NMR, CHN and ICP–AES. A yellow–green photoluminescence (PL) emission with a red shift compared to the PVK:PBD blend was observed. Devices with Zr complexes with the structure ITO/PEDOT:PSS/PVK:PBD/zirconium complex/Al emitted a yellow–red light originating from the Zr complexes. We believe that electroplex occurring at PVK–Zr complex interface is responsible for the red emission in the EL of the device. - Highlights: ► Novel photoluminescence zirconium (IV) complexes with hole transport ligands are synthesized. ► Yellow–green photoluminescence emission is shown red shift rather than PVK:PBD blend. ► The control of the emission properties of OLED devices is explored by adding of π-extended ligands such as Bphen. ► El spectra are shown a red shift of the emission bands in respond to the addition of Π-conjugated ligands. ► Electroplex emission at PVK–Zr complex is proposed.

  14. Red-yellow electroluminescence, yellow-green photoluminescence of novel N, O donor ligands-chelated zirconium (IV) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Shahroosvand, Hashem, E-mail: shahroos@znu.ac.ir [Chemistry Department, University of Zanjan, Zanjan (Iran, Islamic Republic of); Nasouti, Fahimeh [Chemistry Department, University of Zanjan, Zanjan (Iran, Islamic Republic of); Mohajerani, Ezeddin; Khabbazi, Amir [Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2013-03-15

    In this paper, eight new zirconium complexes with 1,2,4,5-benzenetetracarboxylic acid (H{sub 4}btec), 1,10-phenanthroline (phen) and 4,7-diphenyl-1,10-phenanthroline (Bphen), were prepared and used as light emitting material in fabricated OLEDs. The structures of these complexes were characterized by UV-vis, FT-IR spectroscopy, {sup 1}H-NMR, CHN and ICP-AES. A yellow-green photoluminescence (PL) emission with a red shift compared to the PVK:PBD blend was observed. Devices with Zr complexes with the structure ITO/PEDOT:PSS/PVK:PBD/zirconium complex/Al emitted a yellow-red light originating from the Zr complexes. We believe that electroplex occurring at PVK-Zr complex interface is responsible for the red emission in the EL of the device. - Highlights: Black-Right-Pointing-Pointer Novel photoluminescence zirconium (IV) complexes with hole transport ligands are synthesized. Black-Right-Pointing-Pointer Yellow-green photoluminescence emission is shown red shift rather than PVK:PBD blend. Black-Right-Pointing-Pointer The control of the emission properties of OLED devices is explored by adding of {pi}-extended ligands such as Bphen. Black-Right-Pointing-Pointer El spectra are shown a red shift of the emission bands in respond to the addition of {Pi}-conjugated ligands. Black-Right-Pointing-Pointer Electroplex emission at PVK-Zr complex is proposed.

  15. Photoluminescence Enhancement and Structure Repairing of Monolayer MoSe 2 by Hydrohalic Acid Treatment

    KAUST Repository

    Han, Hau-Vei

    2015-12-30

    Atomically thin two-dimensional transition-metal dichalcogenides (TMDCs) have attracted much attention recently due to their unique electronic and optical properties for future optoelectronic devices. The chemical vapor deposition (CVD) method is able to generate TMDCs layers with a scalable size and a controllable thickness. However, the TMDC monolayers grown by CVD may incorporate structural defects, and it is fundamentally important to understand the relation between photoluminescence and structural defects. In this report, point defects (Se vacancies) and oxidized Se defects in CVD-grown MoSe2 monolayers are identified by transmission electron microscopy and X-ray photoelectron spectroscopy. These defects can significantly trap free charge carriers and localize excitons, leading to the smearing of free band-to-band exciton emission. Here, we report that the simple hydrohalic acid treatment (such as HBr) is able to efficiently suppress the trap-state emission and promote the neutral exciton and trion emission in defective MoSe2 monolayers through the p-doping process, where the overall photoluminescence intensity at room temperature can be enhanced by a factor of 30. We show that HBr treatment is able to activate distinctive trion and free exciton emissions even from highly defective MoSe2 layers. Our results suggest that the HBr treatment not only reduces the n-doping in MoSe2 but also reduces the structural defects. The results provide further insights of the control and tailoring the exciton emission from CVD-grown monolayer TMDCs.

  16. Photoluminescence of sol–gel synthesized PZT powders

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Aranda, M.C. [Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología-Universidad Autónoma de San Luis Potosí, Av. Sierra Leona No.550,Col. Lomas 2a. sección, C.P. 78210 San Luis Potosí, SLP, México (Mexico); Calderón-Piñar, F. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); Facultad de Física/IMRE, San Lázaro y L, Universidad de la Habana, C.P. 10400 Habana (Cuba); Hernández-Landaverde, M.A. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); and others

    2016-11-15

    A wide band of photoluminescence (PL) emission in structurally disordered lead zirconate titanate (PZT) powders, prepared by sol–gel route, was observed at room temperature excited with a laser line (488 nm). Powders with PbZr{sub 0.53}Ti{sub 0.47}O{sub 3} nominal composition annealed at different temperatures were studied by X-ray diffraction, Raman spectroscopy, Luminescence, Diffuse Reflectance and Electronic Paramagnetic Resonance Spectroscopy (EPR). Our results indicate that the PL response can be associated to order–disorder degree in the perovskite structure, with the exception of samples annealed at low temperature, where a mixture of oxides precursorsГ—Ві phases was observed. Furthermore, in quasi-crystalline ordered samples (95% of crystallinity) a small generation of PL remains. In these experiments, the band gap increases with the formation of crystalline structure. EPR experiments were conducted in order to follow the evolution of paramagnetic species with thermal treatment from the mixture of oxides precursors to the perovskite phase and paramagnetic point defects were identified (Pb{sup +3} and Ti{sup +3}). EPR data suggest the presence of order–disorder within the lattice network. Paramagnetic species are similar in samples treated at 700 and 800 °C, nevertheless the emission intensity decreases by a factor of 6, indicating that the defects associated with PL are not paramagnetic at both temperatures.

  17. Temperature-dependent photoluminescence from CdS/Si nanoheterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yue Li; Li, Yong; Ji, Peng Fei; Zhou, Feng Qun; Sun, Xiao Jun; Yuan, Shu Qing; Wan, Ming Li [Pingdingshan University, Department of Physics, Solar New Energy Research Center, Pingdingshan (China); Ling, Hong [North China University of Water Resources and Electric Power, Department of Mathematics and Information Science, Zhengzhou (China)

    2016-12-15

    CdS/Si nanoheterojunctions have been fabricated by growing nanocrystal CdS (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) through using a chemical bath deposition method. The nanoheterojunctions have been constructed by three layers: the upper layer being a nc-CdS thin films, the intermediate layer being the interface region including nc-CdS and nanocrystal silicon (nc-Si), and the bottom layer being nc-Si layer grown on sc-Si substrate. The room temperature and temperature-dependent photoluminescence (PL) have been measured and analyzed to provide some useful information of defect states. Utilizing the Gauss-Newton fitting method, five emission peaks from the temperature-dependent PL spectra can be determined. From the high energy to low energy, these five peaks are ascribed to the some luminescence centers which are formed by the oxygen-related deficiency centers in the silicon oxide layer of Si-NPA, the band gap emission of nc-CdS, the transition from the interstitial cadmium (I{sub Cd}) to the valence band, the recombination from I{sub Cd} to cadmium vacancies (V{sub Cd}), and from sulfur vacancies (V{sub s}) to the valence band, respectively. Understanding of the defect states in the CdS/Si nanoheterojunctions is very meaningful for the performance of devices based on CdS/Si nanoheterojunctions. (orig.)

  18. Strong Photoluminescence Enhancement of Silicon Oxycarbide through Defect Engineering

    Directory of Open Access Journals (Sweden)

    Brian Ford

    2017-04-01

    Full Text Available The following study focuses on the photoluminescence (PL enhancement of chemically synthesized silicon oxycarbide (SiCxOy thin films and nanowires through defect engineering via post-deposition passivation treatments. SiCxOy materials were deposited via thermal chemical vapor deposition (TCVD, and exhibit strong white light emission at room-temperature. Post-deposition passivation treatments were carried out using oxygen, nitrogen, and forming gas (FG, 5% H2, 95% N2 ambients, modifying the observed white light emission. The observed white luminescence was found to be inversely related to the carbonyl (C=O bond density present in the films. The peak-to-peak PL was enhanced ~18 and ~17 times for, respectively, the two SiCxOy matrices, oxygen-rich and carbon-rich SiCxOy, via post-deposition passivations. Through a combinational and systematic Fourier transform infrared spectroscopy (FTIR and PL study, it was revealed that proper tailoring of the passivations reduces the carbonyl bond density by a factor of ~2.2, corresponding to a PL enhancement of ~50 times. Furthermore, the temperature-dependent and temperature-dependent time resolved PL (TDPL and TD-TRPL behaviors of the nitrogen and forming gas passivated SiCxOy thin films were investigated to acquire further insight into the ramifications of the passivation on the carbonyl/dangling bond density and PL yield.

  19. Ion-beam synthesis and photoluminescence of SiC nanocrystals assisted by MeV-heavy-ion-beam annealing

    International Nuclear Information System (INIS)

    Khamsuwan, J.; Intarasiri, S.; Kirkby, K.; Chu, P.K.; Singkarat, S.; Yu, L.D.

    2012-01-01

    This work explored a novel way to synthesize silicon carbide (SiC) nanocrystals for photoluminescence. Carbon ions at 90 keV were implanted in single crystalline silicon wafers at elevated temperature, followed by irradiation using xenon ion beams at an energy of 4 MeV with two low fluences of 5 × 10 13 and 1 × 10 14 ions/cm 2 at elevated temperatures for annealing. X-ray diffraction, Raman scattering, infrared spectroscopy and transmission electron microscopy were used to characterize the formation of nanocrystalline SiC. Photoluminescence was measured from the samples. The results demonstrated that MeV-heavy-ion-beam annealing could indeed induce crystallization of SiC nanocrystals and enhance emission of photoluminescence with violet bands dominance due to the quantum confinement effect.

  20. Photoluminescence and nonlinear optical phenomena in plasmonic random media—A review of recent works

    International Nuclear Information System (INIS)

    Araújo, Cid B. de; Kassab, Luciana R.P.; Tolentino Dominguez, C.; Ribeiro, Sidney J.L.; Gomes, Anderson S.L.; Reyna, Albert S.

    2016-01-01

    Photoluminescence properties and nonlinear optical response of metal–dielectric nanocomposites (MDNCs)—germanate glasses, bio-cellulose membranes and colloids containing either silver (Ag) or gold (Au) nanoparticles (NPs)—are reviewed. The phenomena discussed are: i. the photoluminescence enhancement observed from rare-earth doped PbO–GeO 2 glass containing Ag NPs; ii. optical amplification at 1530 nm in RIB waveguides made with PbO–GeO 2 thin films covered with Au NPs; iii. Random Laser emission from a bio-cellulose membrane infiltrated with Rhodamine 6G and containing Ag NPs; iv. the nonlinearity management of high-order processes in colloids containing Ag NPs suspended in acetone. In all discussed cases the influence of the metallic NPs is clearly demonstrated and a procedure to control the nonlinear propagation of light beams in heterogeneous media is presented. - Highlights: • Large photoluminescence enhancement observed from rare-earth doped PbO–GeO 2 glass containing Ag NPs. • Optical amplification at 1530 nm in RIB waveguides made with PbO–GeO 2 thin films covered with Au NPs. • Random Laser emission from a bio-cellulose membrane infiltrated with Rhodamine 6G and containing Ag NPs. • The nonlinearity management of high-order processes in liquid colloids containing Ag NPs.

  1. Influence of LiBr on photoluminescence properties of porous silicon

    International Nuclear Information System (INIS)

    Dimassi, W.; Haddadi, I.; Bousbih, R.; Slama, S.; Ali Kanzari, M.; Bouaicha, M.; Ezzaouia, H.

    2011-01-01

    A new method has been developed to improve the photoluminescence intensity of porous silicon (PS), which is first time that LiBr is used for passivation of PS. Immersion of the PS in a LiBr solution, followed by a thermal treatment at 100 o C for 30 min under nitrogen, leads to a nine fold increase in the intensity of the photoluminescence. The atomic force microscope (AFM) shows an increase of the nanoparticle dimension compared to the initial dimension of the PS nanostructure. The LiBr covers the nanoparticles of silicon without changing the wavelength distribution of the optical excitation and emission spectra. Moreover, a significant decrease of reflectivity was observed for the wavelength in the range of 350-500 nm. - Research highlights: → A new method based on the use of LiBr was developed to enhance nine times the photoluminescence of porous silicon. → The LiBr covers the silicon nanoparticles without changing in the optical excitation and emission spectra. → We observed a significant decrease of the reflectivity in the 350-500 nm spectral range.

  2. Influence of LiBr on photoluminescence properties of porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dimassi, W., E-mail: dimassi_inrst@yahoo.f [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95 Hammam-Lif 2050 (Tunisia); Haddadi, I.; Bousbih, R.; Slama, S.; Ali Kanzari, M.; Bouaicha, M.; Ezzaouia, H. [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95 Hammam-Lif 2050 (Tunisia)

    2011-05-15

    A new method has been developed to improve the photoluminescence intensity of porous silicon (PS), which is first time that LiBr is used for passivation of PS. Immersion of the PS in a LiBr solution, followed by a thermal treatment at 100 {sup o}C for 30 min under nitrogen, leads to a nine fold increase in the intensity of the photoluminescence. The atomic force microscope (AFM) shows an increase of the nanoparticle dimension compared to the initial dimension of the PS nanostructure. The LiBr covers the nanoparticles of silicon without changing the wavelength distribution of the optical excitation and emission spectra. Moreover, a significant decrease of reflectivity was observed for the wavelength in the range of 350-500 nm. - Research highlights: {yields} A new method based on the use of LiBr was developed to enhance nine times the photoluminescence of porous silicon. {yields} The LiBr covers the silicon nanoparticles without changing in the optical excitation and emission spectra. {yields} We observed a significant decrease of the reflectivity in the 350-500 nm spectral range.

  3. Origin of low quantum efficiency of photoluminescence of InP/ZnS nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Shirazi, Roza, E-mail: rozas@fotonik.dtu.dk [Department of Photonics Engineering, Technical University of Denmark, Oersted Plads 343, 2800 Kgs Lyngby (Denmark); Kovacs, Andras [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Peter Grunberg Institute, Forschungszentrum Julich, 52425 Julich (Germany); Dan Corell, Dennis [Department of Photonics Engineering, Technical University of Denmark, Riso, Frederiksborgvej 399, 4000 Roskilde (Denmark); Gritti, Claudia [Department of Photonics Engineering, Technical University of Denmark, Oersted Plads 343, 2800 Kgs Lyngby (Denmark); Thorseth, Anders; Dam-Hansen, Carsten; Michael Petersen, Paul [Department of Photonics Engineering, Technical University of Denmark, Riso, Frederiksborgvej 399, 4000 Roskilde (Denmark); Kardynal, Beata [Department of Photonics Engineering, Technical University of Denmark, Oersted Plads 343, 2800 Kgs Lyngby (Denmark); PGI-9, Forschungszentrum Julich, JARA FIT, 52425 Julich (Germany)

    2014-01-15

    In this paper, we study the origin of a strong wavelength dependence of the quantum efficiency of InP/ZnS nanocrystals. We find that while the average size of the nanocrystals increased by 50%, resulting in longer emission wavelength, the quantum efficiency drops more than one order of magnitude compared to the quantum efficiency of the small nanocrystals. By correlating this result with the time-resolved photoluminescence we find that the reduced photoluminescence efficiency is caused by a fast growing fraction of non-emissive nanocrystals while the quality of the nanocrystals that emit light is similar for all samples. Transmission electron microscopy reveals the polycrystalline nature of many of the large nanocrystals, pointing to the grain boundaries as one possible site for the photoluminescence quenching defects. -- Highlights: • We investigate drop of quantum efficiency of InP/ZnS nanocrystals emitting at longer wavelengths. • We correlate quantum efficiency measurements with time-resolved carrier dynamics. • We find that only a small fraction of larger nanocrystals is optically active.

  4. Origin of low quantum efficiency of photoluminescence of InP/ZnS nanocrystals

    International Nuclear Information System (INIS)

    Shirazi, Roza; Kovacs, Andras; Dan Corell, Dennis; Gritti, Claudia; Thorseth, Anders; Dam-Hansen, Carsten; Michael Petersen, Paul; Kardynal, Beata

    2014-01-01

    In this paper, we study the origin of a strong wavelength dependence of the quantum efficiency of InP/ZnS nanocrystals. We find that while the average size of the nanocrystals increased by 50%, resulting in longer emission wavelength, the quantum efficiency drops more than one order of magnitude compared to the quantum efficiency of the small nanocrystals. By correlating this result with the time-resolved photoluminescence we find that the reduced photoluminescence efficiency is caused by a fast growing fraction of non-emissive nanocrystals while the quality of the nanocrystals that emit light is similar for all samples. Transmission electron microscopy reveals the polycrystalline nature of many of the large nanocrystals, pointing to the grain boundaries as one possible site for the photoluminescence quenching defects. -- Highlights: • We investigate drop of quantum efficiency of InP/ZnS nanocrystals emitting at longer wavelengths. • We correlate quantum efficiency measurements with time-resolved carrier dynamics. • We find that only a small fraction of larger nanocrystals is optically active

  5. Photoluminescence and nonlinear optical phenomena in plasmonic random media—A review of recent works

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, Cid B. de, E-mail: cid@df.ufpe.br [Departamento de Física , Universidade Federal de Pernambuco, 50670-901 Recife , PE (Brazil); Kassab, Luciana R.P. [Faculdade de Tecnologia de São Paulo (FATEC-SP , CEETEPS), 01124-060 São Paulo , SP (Brazil); Tolentino Dominguez, C. [Laboratório de Óptica Biomédica e Imagem , Universidade Federal de Pernambuco , Recife 50740-530, PE (Brazil); Ribeiro, Sidney J.L. [Institute of Chemistry , São Paulo State University (UNESP), 14801-970 Araraquara , SP (Brazil); Gomes, Anderson S.L.; Reyna, Albert S. [Departamento de Física , Universidade Federal de Pernambuco, 50670-901 Recife , PE (Brazil)

    2016-01-15

    Photoluminescence properties and nonlinear optical response of metal–dielectric nanocomposites (MDNCs)—germanate glasses, bio-cellulose membranes and colloids containing either silver (Ag) or gold (Au) nanoparticles (NPs)—are reviewed. The phenomena discussed are: i. the photoluminescence enhancement observed from rare-earth doped PbO–GeO{sub 2} glass containing Ag NPs; ii. optical amplification at 1530 nm in RIB waveguides made with PbO–GeO{sub 2} thin films covered with Au NPs; iii. Random Laser emission from a bio-cellulose membrane infiltrated with Rhodamine 6G and containing Ag NPs; iv. the nonlinearity management of high-order processes in colloids containing Ag NPs suspended in acetone. In all discussed cases the influence of the metallic NPs is clearly demonstrated and a procedure to control the nonlinear propagation of light beams in heterogeneous media is presented. - Highlights: • Large photoluminescence enhancement observed from rare-earth doped PbO–GeO{sub 2} glass containing Ag NPs. • Optical amplification at 1530 nm in RIB waveguides made with PbO–GeO{sub 2} thin films covered with Au NPs. • Random Laser emission from a bio-cellulose membrane infiltrated with Rhodamine 6G and containing Ag NPs. • The nonlinearity management of high-order processes in liquid colloids containing Ag NPs.

  6. Defects or charge transfer: Different possibilities to explain the photoluminescence in crystalline Ba(Zr{sub x}Ti{sub 1−x})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Agda E., E-mail: agda@fct.unesp.br [Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, Presidente Prudente, SP (Brazil); Sasaki, Guilherme S.; Camacho, Sabrina A.; Teixeira, Silvio R. [Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, Presidente Prudente, SP (Brazil); Li, Maximo S. [Universidade de São Paulo, Instituto de Física, São Carlos, SP (Brazil); Longo, Elson [Universidade estadual Paulista, Instituto de Química, Araraquara, SP (Brazil)

    2016-11-15

    In this work, BZT (Ba (Zr{sub x}Ti{sub 1−x})O{sub 3}), composite ceramic powder with x=0, 0.25, 0.50, 0.75 and 1 (mol) was prepared by the microwave-assisted hydrothermal method. The structural, morphological and optical properties of the compounds were determined by XRD, SEM, Raman, UV–vis and photoluminescence analysis. The results showed that the stability of the BZ phase was strongly influenced by the isomorphic Zr/Ti substitution, and that the BZ sample had the greatest structural order for short and long distances compared to the other. The BZT ceramic composite showed optical behavior also influenced by the concentration of Zr, resulting in a growing photoluminescence emission with increasing Zr ion in the network. The BZ sample showed higher photoluminescent intensity in a region including the entire visible spectrum. Although the effect of photoluminescence in these materials is dependent on the presence of defects, which produce excitons for radiative recombination, in the BZ compound, there might have been other effects causing the intense photoluminescence. In this case, high emission is associated with the a charge transfer between neighboring clusters [ZrO{sub 6}] in a nanoparticle surface interface, which in turn are joined to form BZ mesocrystals on a micrometer scale. The photoluminescence observed in the BZT compound had a predominantly white color, a feature that gives it high potential for applications in white light-emitting devices.

  7. Photoluminescence properties of ZnO thin films grown by using the hydrothermal technique

    International Nuclear Information System (INIS)

    Sahoo, Trilochan; Jang, Leewoon; Jeon, Juwon; Kim, Myoung; Kim, Jinsoo; Lee, Inhwan; Kwak, Joonseop; Lee, Jaejin

    2010-01-01

    The photoluminescence properties of zinc-oxide thin films grown by using the hydrothermal technique have been investigated. Zinc-oxide thin films with a wurtzite symmetry and c-axis orientation were grown in aqueous solution at 90 .deg. C on sapphire substrates with a p-GaN buffer layer by using the hydrothermal technique. The low-temperature photoluminescence analysis revealed a sharp bound-exciton-related luminescence peak at 3.366 eV with a very narrow peak width. The temperature-dependent variations of the emission energy and of the integrated intensity were studied. The activation energy of the bound exciton complex was calculated to be 7.35 ± 0.5 meV from the temperature dependent quenching of the integral intensities.

  8. Mechanoluminescence and photoluminescence of Pr3+ activated KMgF3 phosphor

    International Nuclear Information System (INIS)

    Dhoble, S.J.; Kher, R.S.; Furetta, C.

    2003-01-01

    A Czochralski method for the preparation of crystalline KMgF 3 : Pr phosphors are reported. Photoluminescence (PL) and mechanoluminescence (ML) characteristics are studied. Photoluminescence of Pr 3+ activated KMgF 3 shows the strong emission of Pr 3+ ions were observed at 498 and 650 nm by excitation of 213 mn. ML of KMgF 3 : Pr 3+ shows two peaks, which have been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radical (anion radical produced by γ-irradiation) released from two type traps during the mechanical pressure applied on KMgF 3 : Pr 3+ phosphor. It has a supra linear ML response with γ-ray exposure and a negligible fading. These properties of phosphor should be suitable in dosimetry of ionization relation using ML technique. Therefore the KMgF 3 : Pr 3+ phosphor proposed for ML dosimetry of ionization radiations. (Author)

  9. The correlation of blue shift of photoluminescence and morphology of silicon nanoporous

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jumaili, Batool E. B., E-mail: batooleneaze@gmail.com [Department of Physics, (UPM), Serdang, Selangor 43400 (Malaysia); Department of Physics, Anbar University (Iraq); Talib, Zainal A.; Josephine, L.Y.; Paiman, Suriati B.; Muh’d, Ibrahim B.; Mofdal, Manahil E. E. [Department of Physics, (UPM), Serdang, Selangor 43400 (Malaysia); Ahmed, Naser M.; Abdulateef, Sinan A. [School of Physics, USM, 11800 Penang (Malaysia); Al-Jumaily, Abdulmajeed H. J. [Department of Computer and Communication Systems Engineering, Universiti Putra Malaysia (UPM), Serdang, Selangor 43400 (Malaysia); Ramizy, Asmiet [Department of Physics, Anbar University (Iraq)

    2016-07-06

    Porous silicon with diameters ranging from 6.41 to 7.12 nm were synthesized via electrochemical etching by varied anodization current density in ethanoic solutions containing aqueous hydrofluoric acid up to 65 mA/cm{sup 2}.The luminescence properties of the nanoporous at room temperature were analyzed via photoluminescence spectroscopy. Photoluminescence PL spectra exhibit a broad emission band in the range of 360-700 nm photon energy. The PL spectrum has a blue shift in varied anodization current density; the blue shift incremented as the existing of anodization although the intensity decreased. The current blue shift is owning to alteration of silicon nanocrystal structure at the superficies. The superficial morphology of the PS layers consists of unified and orderly distribution of nanocrystalline Si structures, have high porosity around (93.75%) and high thickness 39.52 µm.

  10. Photoluminescence study of ZnS and ZnS:Pb nanoparticles

    International Nuclear Information System (INIS)

    Virpal,; Hastir, Anita; Kaur, Jasmeet; Singh, Gurpreet; Singh, Ravi Chand

    2015-01-01

    Photoluminescence (PL) study of pure and 5wt. % lead doped ZnS prepared by co-precipitation method was conducted at room temperature. The prepared nanoparticles were characterized by X-ray Diffraction (XRD), UV-Visible (UV-Vis) spectrophotometer, Photoluminescence (PL) and Raman spectroscopy. XRD patterns confirm cubic structure of ZnS and PbS in doped sample. The band gap energy value increased in case of Pb doped ZnS nanoparticles. The PL spectrum of pure ZnS was de-convoluted into two peaks centered at 399nm and 441nm which were attributed to defect states of ZnS. In doped sample, a shoulder peak at 389nm and a broad peak centered at 505nm were observed. This broad green emission peak originated due to Pb activated ZnS states

  11. Formation of photoluminescent n-type macroporous silicon: Effect of magnetic field and lateral electric potential

    Energy Technology Data Exchange (ETDEWEB)

    Antunez, E.E. [Centro de Investigación en Ingeniería y Ciencias Aplicadas, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, CP 62210 (Mexico); Estevez, J.O. [Instituto de Física, B. Universidad Autónoma de Puebla, A.P. J-48, Puebla 72570 (Mexico); Campos, J. [Instituto de Energías Renovables, UNAM, Priv. Xochicalco S/N, Temixco, Morelos, CP 62580 (Mexico); Basurto-Pensado, M.A. [Centro de Investigación en Ingeniería y Ciencias Aplicadas, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, CP 62210 (Mexico); Agarwal, V., E-mail: vagarwal@uaem.mx [Centro de Investigación en Ingeniería y Ciencias Aplicadas, UAEM, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, CP 62210 (Mexico)

    2014-11-15

    Metal electrode-free electrochemical etching of low doped n-type silicon substrates, under the combined effect of magnetic and lateral electric field, is used to fabricate photoluminescent n-type porous silicon structures in dark conditions. A lateral gradient in terms of structural characteristics (i.e. thickness and pore dimensions) along the electric field direction is formed. Enhancement of electric and magnetic field resulted in the increase of pore density and a change in the shape of the macropore structure, from circular to square morphology. Broad photoluminescence (PL) emission from 500 to 800 nm, with a PL peak wavelength ranging from 571 to 642 nm, is attributed to the wide range of microporous features present on the porous silicon layer.

  12. Photoluminescent properties of ZnS nanoparticles prepared by electro-explosion of Zn wires

    International Nuclear Information System (INIS)

    Goswami, Navendu; Sen, P.

    2007-01-01

    We study the photoluminescent properties of ZnS nanoparticles without the influence of dopants or magnetic impurities. The ZnS nanoparticles reported in this case were synthesized by a novel method of electro-explosion of wire (EEW). The nanoparticles were prepared employing electro-explosion of pure zinc wires in a cell filled with sulfide ions to produce a free-standing compound ZnS semiconductor. To investigate the structural and optical properties, these nanoparticles were characterized by X-ray powder diffraction (XRD), atomic force microscopy (AFM), UV-visible and photoluminescence (PL) spectroscopy. Consistent with the enhancement of the PL intensity of the 443 nm peak due to deep blue emission of ZnS particles, the XRD of the nanoparticles reveals a hexagonal phase of ZnS nanocrystallites prepared by our novel synthesis technique

  13. [The photoluminescence and absorption properties of Co/AAO nano-array composites].

    Science.gov (United States)

    Li, Shou-Yi; Wang, Cheng-Wei; Li, Yan; Wang, Jian; Ma, Bao-Hong

    2008-03-01

    Ordered Co/AAO nano-array structures were fabricated by alternating current (AC) electrodeposition method within the cylindrical pores of anodic aluminum oxide (AAO) template prepared in oxalic acid electrolyte. The photoluminescence (PL) emission and photoabsorption of AAO templates and Co/AAO nano-array structures were investigated respectively. The results show that a marked photoluminescence band of AAO membranes occurs in the wavelength range of 350-550 nm and their PL peak position is at 395 nm. And with the increase in the deposition amount of Co nanoparticles, the PL intensity of Co/AAO nano-array structures decreases gradually, and their peak positions of the PL are invariable (395 nm). Meanwhile the absorption edges of Co/AAO show a larger redshift, and the largest shift from the near ultraviolet to the infrared exceeds 380 nm. The above phenomena caused by Co nano-particles in Co/AAO composite were analyzed.

  14. Magnetic enhancement of photoluminescence from blue-luminescent graphene quantum dots

    Science.gov (United States)

    Chen, Qi; Shi, Chentian; Zhang, Chunfeng; Pu, Songyang; Wang, Rui; Wu, Xuewei; Wang, Xiaoyong; Xue, Fei; Pan, Dengyu; Xiao, Min

    2016-02-01

    Graphene quantum-dots (GQDs) have been predicted and demonstrated with fascinating optical and magnetic properties. However, the magnetic effect on the optical properties remains experimentally unexplored. Here, we conduct a magneto-photoluminescence study on the blue-luminescence GQDs at cryogenic temperatures with magnetic field up to 10 T. When the magnetic field is applied, a remarkable enhancement of photoluminescence emission has been observed together with an insignificant change in circular polarization. The results have been well explained by the scenario of magnetic-field-controlled singlet-triplet mixing in GQDs owing to the Zeeman splitting of triplet states, which is further verified by temperature-dependent experiments. This work uncovers the pivotal role of intersystem crossing in GQDs, which is instrumental for their potential applications such as light-emitting diodes, photodynamic therapy, and spintronic devices.

  15. A study of photoluminescence and micro-Raman scattering in C-implanted GaN

    International Nuclear Information System (INIS)

    Zhang Limin; Zhang Xiaodong; Liu Zhengmin

    2010-01-01

    GaN samples (no yellow luminescence) in their as-grown states were implanted with 10 13 -10 17 C ions/cm 2 and studied by photoluminescence spectra and micro-Raman scattering spectra. The photoluminescence study showed that yellow luminescence were produced in the C-implanted GaN after 950 degree C annealing, and the peaks of the near band edge emissions showed blue-shifts after C implantation. The Raman measurements indicated that the stresses in GaN films did not change after C implantation. The samples implanted with 10 15 cm -2 carbon ions had the Raman peak at 300 cm -1 , which is associated to the disorder-activated Raman scattering. However, further increasing the implantation dose resulted decreased intensity of the 300 cm -1 peak, due to the ion beam current increase with the implantation dose. (authors)

  16. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum La(Bpy)2q

    International Nuclear Information System (INIS)

    Kumar, Rahul; Bhargava, Parag

    2016-01-01

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy) 2 q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy) 2 q in ethanol showed absorption peak at 385nm, which may be attributed due to (π – π*) transitions. The photoluminescence spectra of La(Bpy) 2 q in ethanol solution showed intense peak at 490 nm

  17. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum La(Bpy)2q

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rahul, E-mail: id-kumarrahul003@gmail.com; Bhargava, Parag [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology-Bombay, Mumbai-400076 (India)

    2016-05-06

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2’bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy){sub 2}q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy){sub 2}q in ethanol showed absorption peak at 385nm, which may be attributed due to (π – π*) transitions. The photoluminescence spectra of La(Bpy){sub 2}q in ethanol solution showed intense peak at 490 nm.

  18. Synthesis and characterization of a new photoluminescent material (8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum La(Bpy)2q

    Science.gov (United States)

    Kumar, Rahul; Bhargava, Parag

    2016-05-01

    A new photoluminescence material, (8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum has been synthesized and characterized by different techniques. The prepared material La(Bpy)2q was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) shows the thermal stability up to 190°C.Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy)2q in ethanol showed absorption peak at 385nm, which may be attributed due to (π - π*) transitions. The photoluminescence spectra of La(Bpy)2q in ethanol solution showed intense peak at 490 nm

  19. Donor-acceptor-pair emission characterization in N-B doped fluorescent SiC

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Kamiyama, Satoshi

    2011-01-01

    In the present work, we investigated donor-acceptor-pair emission in N-B doped fluorescent 6H-SiC, by means of photoluminescence, Raman spectroscopy, and angle-resolved photoluminescence. The photoluminescence results were interpreted by using a band diagram with Fermi-Dirac statistics. It is shown...... intensity in a large emission angle range was achieved from angle-resolved photoluminescence. The results indicate N-B doped fluorescent SiC as a good wavelength converter in white LEDs applications....

  20. Green and fast synthesis of amino-functionalized graphene quantum dots with deep blue photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, E., E-mail: eduardo.blanco@uca.es; Blanco, G.; Gonzalez-Leal, J. M.; Barrera, M. C.; Domínguez, M.; Ramirez-del-Solar, M. [University of Cádiz, Institute of Electron Microscopy and Materials (Spain)

    2015-05-15

    Graphene quantum dots (GQDs) were prepared using a top-down approach with a green microwave-assisted hydrothermal synthesis from ultrathin graphite, previously ultrasound delaminated. Results obtained by transmission electron microscopy and atomic force microscopy indicate that the so-fabricated GQDs are plates with 6 nm of average diameter, mostly single- or bi-layered. Photoluminescence characterization shows that the strongest emission occurs at 410–415 nm wavelength when the samples are excited at 310–320 nm wavelength. In addition to these down-conversion features, GQDs also exhibit up-conversion photoluminescence when excited in the range 560–800 nm wavelength, with broad emission peaks at 410–450 nm wavelength. Analysis of X-ray photoelectron spectroscopy measurements indicates a higher proportion of C–C sp{sup 2} than sp{sup 3} bonds, with the sp{sup 3} ones mainly located at the GQD surfaces. Also evidences of C–O and C–N bonds at the GQD surface have been observed. The combination of these results with Raman and ultraviolet–visible absorption experiments allows envisaging the GQDs to be composed of amino-functionalized sp{sup 2} islands with a high degree of surface oxidation. This would explain the photoluminescent properties observed in the samples under study. The combined up- and down-conversion photoluminescence processes would made these GQDs a powerful energy-transfer component in GQDs–TiO{sub 2} nanocomposite systems, which could be used in photocatalyst devices with superior performance compared to simple TiO{sub 2} systems.

  1. Photoluminescence study of MBE grown InGaN with intentional indium segregation

    International Nuclear Information System (INIS)

    Cheung, Maurice C.; Chen, Fei; Furis, Madalina; Cartwright, Alexander N.; Namkoong, Gon; Doolittle, W. Alan; Pudavar, Haridas E.

    2005-01-01

    Proper control of MBE growth conditions has yielded an In 0.13 Ga 0.87 N thin film sample with emission consistent with In-segregation. The photoluminescence (PL) from this epilayer showed multiple emission components. Moreover, temperature and power dependent studies of the PL demonstrated that two of the components were excitonic in nature and consistent with indium phase separation. At 15 K, time resolved PL showed a non-exponential PL decay that was well fitted with the stretched exponential solution expected for disordered systems. Consistent with the assumed carrier hopping mechanism of this model, the effective lifetime, τ, and the stretched exponential parameter, β, decrease with increasing emission energy. Finally, room temperature micro-PL using a confocal microscope showed spatial clustering of low energy emission. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Photoluminescence study of MBE grown InGaN with intentional indium segregation

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Maurice C.; Chen, Fei; Furis, Madalina; Cartwright, Alexander N. [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Namkoong, Gon; Doolittle, W. Alan [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Pudavar, Haridas E. [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States)

    2005-05-01

    Proper control of MBE growth conditions has yielded an In{sub 0.13}Ga{sub 0.87}N thin film sample with emission consistent with In-segregation. The photoluminescence (PL) from this epilayer showed multiple emission components. Moreover, temperature and power dependent studies of the PL demonstrated that two of the components were excitonic in nature and consistent with indium phase separation. At 15 K, time resolved PL showed a non-exponential PL decay that was well fitted with the stretched exponential solution expected for disordered systems. Consistent with the assumed carrier hopping mechanism of this model, the effective lifetime, {tau}, and the stretched exponential parameter, {beta}, decrease with increasing emission energy. Finally, room temperature micro-PL using a confocal microscope showed spatial clustering of low energy emission. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Femtosecond pulsed laser ablation in microfluidics for synthesis of photoluminescent ZnSe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chao, E-mail: chaoyangscu@gmail.com [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Feng, Guoying, E-mail: guoing_feng@scu.edu.cn [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Dai, Shenyu, E-mail: 232127079@qq.com [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Wang, Shutong, E-mail: wangshutong.scu@gmail.com [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Li, Guang, E-mail: 632524844@qq.com [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Zhang, Hua [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); Zhou, Shouhuan, E-mail: zhoush@scu.edu.cn [College of Electronics and Information Engineering, Sichuan University, No. 24 South Section 1, 1st Ring Road, Chengdu 610064 (China); North China Research Institute of Electro-Optics, 4 Jiuxianqiao Street, Chaoyang District, Beijing 100015 (China)

    2017-08-31

    Highlights: • A novel method for synthesis and coating of quantum dots by ultrafast laser pulses. • Mild and “green” synthesis method without toxic chemicals. • Enhanced bright green light emission without doped transition metal ions. • Ultrafast laser and coating layer enhanced the emission originated from defects. - Abstract: A simple but new toxic chemical free method, Femtosecond Laser Ablation in Microfluidics (FLAM) was proposed for the first time. ZnSe quantum dots of 4–6 nm were synthesized and with the use of hyperbranched Polyethyleneimine (PEI) as both structural and functional coated layer. These aqueous nanosized micelles consisting of quantum dots exhibit deep defect states emission of bright green light centered at 500 nm. A possible mechanism for the enhanced board band emission was discussed. The properties of toxic matters free and enhanced photoluminescence without doped transition metal ions demonstrate an application potential for biomedical imaging.

  4. MOF-5 decorated hierarchical ZnO nanorod arrays and its photoluminescence

    Science.gov (United States)

    Zhang, Yinmin; Lan, Ding; Wang, Yuren; Cao, He; Jiang, Heng

    2011-04-01

    The strategy to manipulate nanoscale materials into well-organized hierarchical architectures is very important to both material synthesis and nanodevice applications. Here, nanoscale MOF-5 crystallites were successfully fabricated onto ordered hierarchical ZnO arrays based on aqueous chemical synthesis and molecule self-assembly technology guided room temperature diffusion method, which has the advantages of energy saving and simple operation. The structures and morphologies of the samples were performed by X-ray powder diffraction and field emission scanning electronic microscopy. The MOF-5 crystallites have good quality and bind well to the hexagonal-patterned ZnO arrays. The photoluminescence spectrum shows that the emission of hybrid MOF-5-ZnO films displays a blue shift in green emission and intensity reduction in UV emission. This ordered hybrid semiconductor material is expected to exploit the great potentiality in sensors, micro/nanodevices, and screen displays.

  5. Femtosecond pulsed laser ablation in microfluidics for synthesis of photoluminescent ZnSe quantum dots

    International Nuclear Information System (INIS)

    Yang, Chao; Feng, Guoying; Dai, Shenyu; Wang, Shutong; Li, Guang; Zhang, Hua; Zhou, Shouhuan

    2017-01-01

    Highlights: • A novel method for synthesis and coating of quantum dots by ultrafast laser pulses. • Mild and “green” synthesis method without toxic chemicals. • Enhanced bright green light emission without doped transition metal ions. • Ultrafast laser and coating layer enhanced the emission originated from defects. - Abstract: A simple but new toxic chemical free method, Femtosecond Laser Ablation in Microfluidics (FLAM) was proposed for the first time. ZnSe quantum dots of 4–6 nm were synthesized and with the use of hyperbranched Polyethyleneimine (PEI) as both structural and functional coated layer. These aqueous nanosized micelles consisting of quantum dots exhibit deep defect states emission of bright green light centered at 500 nm. A possible mechanism for the enhanced board band emission was discussed. The properties of toxic matters free and enhanced photoluminescence without doped transition metal ions demonstrate an application potential for biomedical imaging.

  6. Photoluminescence of Er in SiOx

    International Nuclear Information System (INIS)

    Wan Jun; Sheng Chi; Lu Fang; Gong Dawei; Fan Yongliang; Lin Feng; Wang Xun

    1998-01-01

    Erbium-doped SiO x is prepared by molecular beam epitaxy. The influence of Er on the incorporation of O is studied by using Auger spectroscopy. Photoluminescence (PL) peaks around the wave-length of 1.53 μm have been observed within the temperature range of 18 to 300 K after annealing. The relationship between PL intensity and annealing temperature is discussed. The temperature dependence of the PL intensity shows an exponential decay with an activation energy of 12 meV at low temperatures ( 100 K)

  7. Photoluminescence study in diaminobenzene functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Abhisek, E-mail: guptaabhisek017@gmail.com, E-mail: cnssks@iacs.res.in; Saha, Shyamal K., E-mail: guptaabhisek017@gmail.com, E-mail: cnssks@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2014-10-15

    Being an excellent electronic material graphene is a very poor candidate for optoelectronic applications. One of the major strategies to develop the optical property in GO is the functionalization of graphene oxide (GO). In the present work GO sheets are functionalized by o-phenylenediamine to achieve diaminobenzene functionalized GO composite (DAB-GO). Formation of DAB-GO composite is further characterized by FTIR, UV, Raman studies. Excellent photoluminescence is observed in DAB-GO composite via passivation of the surface reactive sites by ring-opening amination of epoxides of GO.

  8. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...... and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we...

  9. Photoluminescence enhancement from GaN by beryllium doping

    Science.gov (United States)

    García-Gutiérrez, R.; Ramos-Carrazco, A.; Berman-Mendoza, D.; Hirata, G. A.; Contreras, O. E.; Barboza-Flores, M.

    2016-10-01

    High quality Be-doped (Be = 0.19 at.%) GaN powder has been grown by reacting high purity Ga diluted alloys (Be-Ga) with ultra high purity ammonia in a horizontal quartz tube reactor at 1200 °C. An initial low-temperature treatment to dissolve ammonia into the Ga melt produced GaN powders with 100% reaction efficiency. Doping was achieved by dissolving beryllium into the gallium metal. The powders synthesized by this method regularly consist of two particle size distributions: large hollow columns with lengths between 5 and 10 μm and small platelets in a range of diameters among 1 and 3 μm. The GaN:Be powders present a high quality polycrystalline profile with preferential growth on the [10 1 bar 1] plane, observed by means of X-ray diffraction. The three characteristics growth planes of the GaN crystalline phase were found by using high resolution TEM microscopy. The optical enhancing of the emission in the GaN powder is attributed to defects created with the beryllium doping. The room temperature photoluminescence emission spectra of GaN:Be powders, revealed the presence of beryllium on a shoulder peak at 3.39 eV and an unusual Y6 emission at 3.32eV related to surface donor-acceptor pairs. Also, a donor-acceptor-pair transition at 3.17 eV and a phonon replica transition at 3.1 eV were observed at low temperature (10 K). The well-known yellow luminescence band coming from defects was observed in both spectra at room and low temperature. Cathodoluminescence emission from GaN:Be powders presents two main peaks associated with an ultraviolet band emission and the yellow emission known from defects. To study the trapping levels related with the defects formed in the GaN:Be, thermoluminescence glow curves were obtained using UV and β radiation in the range of 50 and 150 °C.

  10. Photoluminescence and thermally stimulated luminescence characteristics of rice flour

    International Nuclear Information System (INIS)

    Murthy, K.V.R.; Rey, L.; Belon, P.

    2007-01-01

    The present paper reports the photoluminescence (PL) and the thermoluminescence (TL) characteristics of rice flour. This study is undertaken to consider storage of rice at low temperature and irradiation for disinfection. From the Indian market a few varieties of rice was bought. All the samples of rice was ground using an agate motor and pestle. Thereafter, the powder was sieved to the size of 140 μm using appropriate sieves. When comparing the PL characteristics of the different rice powders studied, it is interesting to note that the PL emission wavelength (around 445 nm) is nearly same for all the rice varieties studied even though the excitation wave length is different. TL characteristics are studied in the temperature range 77-230 K as well as 300-700 K. TL is recorded for the virgin samples and also on irradiation of the same by exposing it to X-ray at 77 K, beta at 300 K and gamma at 77 K. The two varieties are given an X-ray dose of 1 kGy. The TL is recorded for 200 mg rice powder. The TL displayed for the as-received 1 kGy X- ray dose peak is around 160 K with a broad shoulder around 120 K. Basmati variety is given a gamma dose of 12.5 kGy and the TL and TL emission is recorded. It is seen that a well-defined low-temperature TL peak around 119 K and a hump around 145 K are observed in the sample. The TL emission is around 430 nm.The TL peak observed in most of the rice samples above room temperature is around 558 K

  11. Investigation on photoluminescence, electrical and positron lifetime of Eu"3"+ activated Gd_2O_3 phosphors

    International Nuclear Information System (INIS)

    Selvalakshmi, Thangaraj; Sellaiyan, Selvakumar; Uedono, Akira; Chandra Bose, Arumugam

    2015-01-01

    In the present study, red emitting Gd_2O_3:Eu"3"+ phosphors are prepared by citrate-based sol–gel process and the as-prepared samples are annealed at various annealing temperatures. The photoluminescence properties of Gd_2O_3:Eu"3"+ is explained from the excitation and emission spectra. The excitation spectra include peaks corresponding to charge transfer and 4f–4f transitions of Eu"3"+ and Gd"3"+. The phosphors exhibit a weak energy transfer process from Gd"3"+ to Eu"3"+. Under the excitation of 254 nm, a sharp red emission peak is observed at 611 nm and the emission intensity increases with the annealing temperature. The presence of defects in the phosphor is investigated by positron annihilation lifetime and Doppler broadening spectroscopy. The relation between visible emission and lattice defects of the phosphors is presented. The electrical and dielectric properties of the phosphor are also discussed in detail. Such red emitting phosphors pave the way towards the fabrication of light emitting diodes (LEDs). - Highlights: • Positron annihilation lifetime spectroscopy of Gd_2O_3:Eu"3"+. • Relation between positron lifetime and photoluminescence. • Conductivity and dielectric properties of Gd_2O_3:Eu"3"+.

  12. Temperature-dependent photoluminescence study of InP/ZnS quantum dots

    Science.gov (United States)

    Thuy Pham, Thi; Tran, Thi Kim Chi; Liem Nguyen, Quang

    2011-06-01

    This paper reports on the temperature-dependent photoluminescence of InP/ZnS quantum dots under 532 nm excitation, which is above the InP transition energy but well below that of ZnS. The overall photoluminescence spectra show two spectral components. The higher-energy one (named X) is assigned to originate from the excitonic transition; while the low-energy spectral component (named I) is normally interpreted as resulting from lattice imperfections in the crystalline structure of InP/ZnS quantum dots (QDs). Peak positions of both the X and I emissions vary similarly with increasing temperature and the same as the InP bandgap narrowing with temperature. In the temperature range from 15 to 80 K, the ratio of the integrated intensity from the X and the I emissions decreases gradually and then this ratio increases fast at temperatures higher than 80 K. This could result from a population of charge carriers in the lattice imperfection states at a temperature below 80 K to increase the I emission but then with these charge carriers being released to contribute to the X emission.

  13. Influence of structural defects on excitonic photoluminescence of pentacene

    International Nuclear Information System (INIS)

    Piryatins'kij, Yu.P.; Kurik, M.V.

    2011-01-01

    The exciton reflection, absorption, and photoluminescence spectra for single crystals and polycrystalline films have been studied in the temperature range of 4.2-296 K. A significant influence of structural defects arising during phase transitions on the exciton spectra of pentacene has been detected. The mechanisms of photoluminescence in single crystals and crystalline films of pentacene have been considered.

  14. Optimized photoluminescence of SrB 2O 4:Eu 3+ red-emitting phosphor by charge compensation

    Science.gov (United States)

    Zhao, Lai-Shi; Liu, Jie; Wu, Zhan-Chao; Kuang, Shao-Ping

    2012-02-01

    A novel red-emitting phosphor, SrB 2O 4:Eu 3+, was synthesized by high temperature solid-state reaction and its photoluminescence properties were studied. The emission spectrum consists of four major emission bands. The emission peaks are located at 593, 612, 650 and 703 nm, corresponding to the 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3 and 5D0 → 7F4 typical transitions of Eu 3+, respectively. The effects of Eu 3+ doping content and charge compensators (Li +, Na +, K +) on photoluminescence of SrB 2O 4:Eu 3+ phosphor were studied. The results show that the emission intensity can be affected by above factors and Na + is the optimal charge compensator for SrB 2O 4:Eu 3+. The photoluminescence of NaSrB 2O 4:Eu 3+ was compared with that of Y 2O 2S:Eu 3+. It implies that SrB 2O 4:Eu 3+ is a good candidate as a red-emitting phosphor pumped by near-ultraviolet (NUV) InGaN chip for fabricating white light-emitting diodes (WLEDs).

  15. Structure, microstructure and photoluminescence of nanocrystalline Ti-doped gahnite

    International Nuclear Information System (INIS)

    Vrankić, M.; Gržeta, B.; Mandić, V.; Tkalčec, E.; Milošević, S.; Čeh, M.; Rakvin, B.

    2012-01-01

    Highlights: ► Ti-doped gahnite samples with 0–11.6 at.% Ti were synthesized for the first time. ► The samples had crystallite size of 16.6–20.5 nm and lattice strain of 0.07–0.26%. ► Titanium entered the gahnite structure as Ti 4+ , substituting for octahedral Al 3+ . ► Ti-doped gahnite showed the UV absorption and blue emission under UV excitation. - Abstract: A series of Ti-doped ZnAl 2 O 4 (gahnite) samples with doping levels of 0, 1.8, 3.8, 5.4 and 11.6 at.% Ti in relation to Al were prepared by a sol–gel technique. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), EPR spectroscopy, UV–vis reflectance spectroscopy and photoluminescence (PL) studies. Diffraction patterns indicated that all samples were nanocrystalline, with a spinel-type structure, space group Fd3 ¯ m. Titanium doping of gahnite caused an increase of unit-cell parameter and diffraction line broadening. The structure of samples was refined by the Rietveld method, simultaneously with the analysis of diffraction line broadening. TEM investigations confirmed that samples had spinel-type structure, and showed that samples contained evenly shaped particles of about 20 nm in size. Ti-doped samples exhibited strong absorption at wavelength exc = 308 nm.

  16. Electric Field-Dependent Photoluminescence in Multilayer Transition Metal Dichalcogenides

    Science.gov (United States)

    Stanev, T. K.; Henning, A.; Sangwan, V. K.; Speiser, N.; Stern, N. P.; Lauhon, L. J.; Hersam, M. C.; Wang, K.; Valencia, D.; Charles, J.; Kubis, T. C.

    Owing to interlayer coupling, transition metal dichalcogenides (TMDCs) such as MoS2 exhibit strong layer dependence of optical and electronic phenomena such as the band gap and trion and neutral exciton population dynamics. Here, we systematically measure the effect of layer number on the optical response of multilayer MoS2 in an external electric field, observing field and layer number dependent emission energy and photoluminescence intensity. These effects are studied in few (2-6) and bulk (11 +) layered structures at low temperatures. In MoS2\\ the observed layer dependence arises from several mechanisms, including interlayer charge transfer, band structure, Stark Effect, Fermi level changes, screening, and surface effects, so it can be challenging to isolate how these mechanisms impact the observables. Because it behaves like a stack of weakly interacting monolayers rather than multilayer or bulk, ReS2 provides a comparison to traditional TMDCs to help isolate the underlying physical mechanisms dictating the response of multilayers. This work is supported by the National Science Foundation MRSEC program (DMR-1121262), and the 2-DARE Grant (EFRI-1433510). N.P.S. is an Alfred P. Sloan Research Fellow.

  17. Origin of photoluminescence in β -G a2O3

    Science.gov (United States)

    Ho, Quoc Duy; Frauenheim, Thomas; Deák, Peter

    2018-03-01

    β -G a2O3 , a candidate material for power electronics and UV optoelectronics, shows strong room-temperature photoluminescence (PL). In addition to the three well-known bands of as-grown samples in the UV, blue, and green, also red PL was observed upon nitrogen doping. This raises the possibility of applying β -G a2O3 nanostructures as white phosphors. Using an optimized, Koopmans-compliant hybrid functional, we show that most intrinsic point defects, as well as substitutional nitrogen, act as deep acceptors, and each of the observed PL bands can be explained by electron recombination with a hole trapped in one of them. We suggest this mechanism to be general in wide-band-gap semiconductors which can only be doped n -type. Calculations on the nitrogen acceptor reproduce the observed red luminescence accurately. Earlier we have shown that not only the energy, but the polarization properties of the UV band can be explained by self-trapped hole states. Here we find that the blue band has its origin mainly in singly negative Ga-O divacancies, and the green band is caused dominantly by interstitial O atoms (with minor contribution of Ga vacancies to both). These assignments can explain the experimentally observed dependence of the PL bands on free-electron concentration and stoichiometry. The information provided here paves the way for the conscious tuning of light emission from β -G a2O3 .

  18. Photoluminescence properties of TiO{sub 2} nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Chetibi, Loubna [University Mentouri Constantine and National Polytechnic School of Constantine, Materials Science and Applications Unit (Algeria); Busko, Tetiana; Kulish, Nikolay Polikarpovich [Kyiv National Taras Shevchenko University (Ukraine); Hamana, Djamel [University Mentouri Constantine and National Polytechnic School of Constantine, Materials Science and Applications Unit (Algeria); Chaieb, Sahraoui [Lawrence Berkeley National Laboratory (United States); Achour, Slimane, E-mail: achourslimane11@yahoo.fr [University Mentouri Constantine and National Polytechnic School of Constantine, Materials Science and Applications Unit (Algeria)

    2017-04-15

    Multi-walled carbon nanotube (MWCNT)-TiO{sub 2} nanofiber (NF) composites forming a layered nanostructure (MWCNTs/TiO{sub 2} NFs/Ti) were prepared by impregnation at low temperature. Room temperature photoluminescence (PL) of these nanostructures shows a broad intense band in the visible light range (∼450–600 nm). The origin of the PL emission which, mainly, resulted from surface oxygen vacancies and other defects was investigated. We studied the effect of MWCNT deposition on the PL of TiO{sub 2} NFs where the MWCNTs can act as an electron reservoir of electrons emitted from TiO{sub 2} nanofibers when irradiated with UV light. The combination of MWCNTs and TiO{sub 2} results in quenching of TiO{sub 2} luminescence in the visible range. In addition, the prepared surface of MWCNTs-TiO{sub 2} was irradiated with Ti{sup +} ions using irradiation energy of 140 keV and doses of 10{sup 13} ions/cm{sup 2}. Also, this treatment induced the PL intensity quenching due to the generation of non-radiative additional levels inside the band gap.

  19. Time-resolved photoluminescence of SiOx encapsulated Si

    Science.gov (United States)

    Kalem, Seref; Hannas, Amal; Österman, Tomas; Sundström, Villy

    Silicon and its oxide SiOx offer a number of exciting electrical and optical properties originating from defects and size reduction enabling engineering new electronic devices including resistive switching memories. Here we present the results of photoluminescence dynamics relevant to defects and quantum confinement effects. Time-resolved luminescence at room temperature exhibits an ultrafast decay component of less than 10 ps at around 480 nm and a slower component of around 60 ps as measured by streak camera. Red shift at the initial stages of the blue luminescence decay confirms the presence of a charge transfer to long lived states. Time-correlated single photon counting measurements revealed a life-time of about 5 ns for these states. The same quantum structures emit in near infrared close to optical communication wavelengths. Nature of the emission is described and modeling is provided for the luminescence dynamics. The electrical characteristics of metal-oxide-semiconductor devices were correlated with the optical and vibrational measurement results in order to have better insight into the switching mechanisms in such resistive devices as possible next generation RAM memory elements. ``This work was supported by ENIAC Joint Undertaking and Laser-Lab Europe''.

  20. Synthesis, characterization and photoluminescence of tin oxide nanoribbons and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M.A., E-mail: duraia_physics@yahoo.co [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Mansorov, Z.A. [Al-Farabi Kazakh National University, Almaty (Kazakhstan); Tokmolden, S. [Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan)

    2009-11-15

    In this work we report the successful formation of tin oxide nanowires and tin oxide nanoribbons with high yield and by using simple cheap method. We also report the formation of curved nanoribbon, wedge-like tin oxide nanowires and star-like nanowires. The growth mechanism of these structures has been studied. Scanning electron microscope was used in the analysis and the EDX analysis showed that our samples is purely Sn and O with ratio 1:2. X-ray analysis was also used in the characterization of the tin oxide nanowire and showed the high crystallinity of our nanowires. The mechanism of the growth of our1D nanostructures is closely related to the vapor-liquid-solid (VLS) process. The photoluminescence PL measurements for the tin oxide nanowires indicated that there are three stable emission peaks centered at wavelengths 630, 565 and 395 nm. The nature of the transition may be attributed to nanocrystals inside the nanobelts or to Sn or O vacancies occurring during the growth which can induce trapped states in the band gap.

  1. Femtosecond transient photoluminescence of the substituted poly(diphenylacetulene)s.

    Science.gov (United States)

    Piskun, N. V.; Wang, D. K.; Lim, H.; Epstein, A. J.; Vanwoerkom, L. D.; Gustafson, T. L.

    2000-03-01

    We present the results of a femtosecond transient photoluminescence (PL) study of solutions of two derivatives of substituted poly(diphenylacetylene) using an up-conversion technique. n-Butyl (nBu) and p-carbazole (Cz) substituted poly(diphenylacetylene), PDPA-nBu and PDPA-Cz respectively, have band gaps determined by maxima in the slope of absorption vs. energy of 2.75 eV and 2.63 eV. The steady state emission peaks are at 2.4 eV for PDPA-nBu and at 2.3 eV for PDPA-Cz respectively. The PL peak for PDPA-Cz is red shifted in comparison to the PL peak for PDPA-nBu. Roles of phenyl groups, electron donating effect of the carbazole side units and planarity of the backbone are discussed. Exciting at 3.1 eV, the fs PL shows a faster decay for PDPA-Cz than that for PDPA-nBu, in accord with the decrease of PL quantum efficiency of PDPA-Cz. The 200 fs - 80 ps PL(t) agrees with ~1 ns lifetime. The PDPA-Cz has larger red shift in the 0.2-20 ps time frame. The origin of that shift will be discussed. This work is supported in part by ONR.

  2. Photoluminescence study of CdSe nanorods embedded in a PVA matrix

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mamta [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh 160014 (India); Tripathi, S.K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh 160014 (India)

    2013-03-15

    Nanometer-sized semiconductor CdSe nanorods have been successfully grown within polyvinyl alcohol (PVA) matrix by in situ technique. PVA:n-CdSe nanorods are characterized by X-ray diffraction, transmission electron microscopy, UV-vis spectrophotometer and photoluminescence spectroscopy. The photoluminescence spectra of PVA:n-CdSe nanorods are studied at different excitation wavelengths. PVA:n-CdSe nanorods have demonstrated to exhibit strong and well-defined green photoluminescence emission. The long-term stability of the PL properties of PVA:n-CdSe nanorods is also investigated in view of possible applications of polymer nanocomposites. The linear optical constants such as the extinction coefficient (k), real ({epsilon}{sub 1}) and imaginary ({epsilon}{sub 2}) dielectric constant, optical conductivity ({sigma}{sub opt}) are calculated for PVA:n-CdSe nanorods. The optical properties i.e. good photostability and larger stokes shift suggesting to apply PVA:n-CdSe nanorods in bioimaging applications. - Highlights: Black-Right-Pointing-Pointer In situ synthesis of PVA:n-CdSe via chemical bath method at room temperature. {open_square} From TEM image, the three arm nanorods morphology of PVA:n-CdSe is obtained. Black-Right-Pointing-Pointer The optical constants i.e. n, k, {epsilon}{sub 1}, {epsilon}{sub 2} and {sigma}{sub opt} are calculated. Black-Right-Pointing-Pointer Exhibiting green band photoemission peak at 540 nm.

  3. Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

    International Nuclear Information System (INIS)

    Deus, R.C.; Cortés, J.A.; Ramirez, M.A.; Ponce, M.A.; Andres, J.; Rocha, L.S.R.

    2015-01-01

    Highlights: • CeO 2 nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO 2 and La-doped CeO 2 particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission

  4. Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

    Energy Technology Data Exchange (ETDEWEB)

    Deus, R.C. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Cortés, J.A., E-mail: leandrosrr89@gmail.com [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ramirez, M.A. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ponce, M.A. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA) (CONICET-Universidad Nacional de Mar del Plata), Juan B. Justo 4302, 7600 Mar del Plata (Argentina); Andres, J. [Laboratório Interdisciplinar em Cerâmica, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, São Paulo (Brazil); Rocha, L.S.R. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); and others

    2015-10-15

    Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.

  5. Glutathione-assisted synthesis of star-shaped zinc oxide nanostructures and their photoluminescence behavior

    International Nuclear Information System (INIS)

    Kavita; Singh, Karamjit; Kumar, Sunil; Bhatti, H.S.

    2014-01-01

    Star-shaped ZnO nanostructures have been synthesized by facile chemical co-precipitation method in the presence of glutathione. Glutathione, a reducing agent, shape modifier and an entirely benign antioxidant; acts as a capping agent in the present study. The powder X-ray diffraction patterns indicate that the novel star-shaped ZnO nanostructures exhibit hexagonal structure. Fourier transform infra-red spectroscopic studies confirmed the anchoring of glutathione on ZnO nanocrystals. Transmission electron microscopy and field emission scanning electron microscopy revealed the star and cube-shaped shaped morphology of the glutathione modified nanocrystals. Optical characterization of synthesized nanocrystals has been done by UV–vis absorption spectroscopy and steady state photoluminescence spectroscopy. Recorded Photoluminescence spectra confirm the multi-chromatic photoluminescence behavior of the synthesized nanostructures. - Highlights: • Morphology has been investigated as a function of capping agent concentration. • Comparison between capped and uncapped ZnO nanoparticles has been examined. • Diffraction scans show the crystalline wurtzite structure of synthesized product. • Recorded PL spectra show the multichromatic behavior of synthesized nanostructures

  6. Influence of plasmon coupling on the photoluminescence of ZnS/Ag nanoparticles obtained by laser irradiation in liquid

    Science.gov (United States)

    Moos, Rafaela; Graff, Ismael L.; de Oliveira, Vinicius S.; Schreiner, Wido H.; Bezerra, Arandi G.

    2017-10-01

    We investigate the photoluminescence, optical absorption and structural properties of ZnS submitted to laser irradiation in water and isopropyl alcohol. Nanoparticles were produced by irradiating micro-sized ZnS particles dispersed in both liquids, with and without the addition of Ag nanoparticles, taking advantage of the laser-assisted fragmentation effect. When ZnS microparticles are irradiated either in pure water or isopropyl alcohol a considerable size reduction is achieved (from micra to few nanometers). The photoluminescence of these nanoparticles mainly occurs in the UV, centered at 350 nm, and with smaller intensity in the visible, centered at 600 nm. Irradiation of ZnS microparticles dispersed in colloidal silver triggers a reaction between both materials, modifying its optical absorption and photoluminescent properties. After irradiation of ZnS in alcohol containing Ag nanoparticles, a giant increase of the UV photoluminescence is observed. Interestingly, when the irradiation is performed in aqueous Ag nanoparticles colloids, the photoluminescence suffers a red-shift towards the violet-blue. The data show that core-shell (Ag-ZnO) nanostructures are formed after irradiation and the visible emission likely originates from the ZnO shell grown around silver nanoparticles. The presence of Ag nanoparticles in the liquid medium promotes a stronger absorption of the laser beam during irradiation due to the coupling with the surface plasmon resonance, fostering intense reactions among ZnS, Ag nanoparticles, and the liquid medium. Our study shows that with a simple change of the liquid medium wherein the irradiation is conducted the photoluminescence can be tuned from UV to visible and core-shell nanostructures can be obtained.

  7. Annealing effect on the photoluminescence properties of ZnO nanorod array prepared by a PLD-assistant wet chemical method

    International Nuclear Information System (INIS)

    Wei Sufeng; Lian Jianshe; Wu Hua

    2010-01-01

    Well-aligned ZnO nanorod arrays were synthesized by a wet chemical method on the glass substrate with ZnO thin film as seed layer prepared by pulsed laser deposition. The effect of annealing temperature on the luminescence characteristics was investigated. As the annealing temperature increased, the photoluminescence properties show a general enhancing tendency. The nanorod array with high ultraviolet emission and negligible visible light emission (designated by the photoluminescence intensity ratio of ultraviolet to visible emission of 66.4) is obtained by annealing the sample at 700 deg. C for 1 h. Based on the results of X-ray photoelectron spectroscopy and photoluminescence spectra, the mechanisms of visible emission were discussed. - Research Highlights: → ZnO nanorod array with good crystallography, low defects concentration and good optical property was obtained after annealed at 700 deg. C for 1 h. → The transition from the conduction band to the O i level may be responsible for the yellow-green emission. → The yellow emission may originate from the presence of Zn(OH) 2 on the surface or the band transition from conduction band to V o Zn i level. → The transition from the Zn i level to the level should produce an orange emission or an orange-red emission.

  8. Influence of particle plasmon resonance on the photoluminescence of organic semiconductor blend

    Science.gov (United States)

    Dou, Fei; Peng, Chunzeng; Liu, Hongmei; Wang, Jiyou; Feng, Shengfei; Zhang, Xinping

    2010-05-01

    We investigate the influence of particle plasmon resonance of Au nanoislands structures on the exciplex emission in the polymer blend of poly (9, 9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly (9,9'-dioctylfluorene-co-bis-N,N'- (4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine) (PFB). The experimental results indicate that when the particle plasmon resonance of the gold nanoisland structures overlaps the spectral range of the exciplex emission, significant enhancement of the photoluminescence can be observed. Furthermore, longer lifetime has been measured for the red-shift emission of the exciplex. We proposed that the localized field due to the particle plasmon resonance of the Au nanoislands has modulated the mechanisms for the formation of exciplex, which may be related to the exciton diffusion, charge transfer, and phase separation at the interface between the two materials.

  9. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    Science.gov (United States)

    Kumar, Danith; Yadav, L. S. Reddy; Lingaraju, K.; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.; Naika, H. Raja; Chikkahanumantharayappa, Nagaraju, G.

    2015-06-01

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm-1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV -Vis spectrum was found to be in the range 5.40-5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  10. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Danith; Chikkahanumantharayappa [Dept. of Physics, Vivekananda First grade College, Bangalore - 560055 (India); Yadav, L. S. Reddy; Nagaraju, G., E-mail: nagarajugn@rediffmail.com [Dept of Chemistry, Siddaganga Institute of Technology, Tumkur, Karnataka-572103 (India); Lingaraju, K.; Naika, H. Raja [Dept. of Environmental Science, Tumkur University, Tumkur, Karnataka-572103 (India); Manjunath, K. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Karnataka-562112 (India); Suresh, D. [Dept. of Chemistry, Tumkur University, Tumkur, Karnataka-572103 (India); Prasad, Daruka [Dept. of Physics, BMS Institute of Technology, Bangalore-560064 (India); Nagabhushana, H. [CNR Rao Center for Advanced Materials, Tumkur University, Tumkur, Karnataka-572103 (India); Sharma, S. C. [Chattisgarh Swami Vivekananda Technological University, Bhilai, Chattisgarh-490009 (India)

    2015-06-24

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  11. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    International Nuclear Information System (INIS)

    Kumar, Danith; Chikkahanumantharayappa; Yadav, L. S. Reddy; Nagaraju, G.; Lingaraju, K.; Naika, H. Raja; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.

    2015-01-01

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm −1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation

  12. Photoluminescence of a single InAs/AlAs quantum dot

    International Nuclear Information System (INIS)

    Shamirzaev, T.S.; Zhuravlev, K.S.; Larsson, M.; Holtz, P.O.

    2008-01-01

    Micro-photoluminescence (μ-PL) of a simple InAs/AlAs quantum dot (QD) has been studied. It has been found that the μ-PL emission related to the recombination in a single QD is strongly broadened probably due to spectral diffusion. Emissions related to the recombination of biexcitons and excitons occupying excited levels of the QD are observed in μ-PL spectra at high excitation power densities. A red shift of the μ-PL emissions related to recombination of excitons in the ground and excited levels of the QD with increasing excitation power gives clear evidence for type I alignment of the InAs/AlAs QD. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Photoluminescence study of ZnO structures grown by aqueous chemical growth

    International Nuclear Information System (INIS)

    Kenanakis, G.; Androulidaki, M.; Vernardou, D.; Katsarakis, N.; Koudoumas, E.

    2011-01-01

    ZnO micro-structures were deposited by aqueous chemical growth on Si (100) substrates, their morphology and size depending on the growth period. Characterization of the structures was performed using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Photoluminescence spectra recorded at 18 and 295 K for 325 nm CW excitation indicated that these are strongly affected by the morphology of the structures. Rods and tubes emit stronger UV radiation, in contrast to stronger yellow-green emission observed for flower-like structures. A red shift of the UV emission was found for increasing input power, while, thermal annealing of the samples induced stimulated emission for quite high excitation intensities.

  14. Photoluminescence Polarization Anisotropy in a Single Heterostructured III-V Nanowire with Mixed Crystal Phases

    International Nuclear Information System (INIS)

    Moses, A. F.; Hoang, T. B.; Ahtapodov, L.; Dheeraj, D. L.; Fimland, B. O.; Weman, H.; Helvoort, A. T. J. van

    2011-01-01

    Low temperature (10 K) micro-photoluminescence (μ-PL) of single GaAs/AlGaAs core-shell nanowires with single GaAsSb inserts were measured. The PL emission from the zinc blende GaAsSb insert is strongly polarized along the nanowire axis while the PL emission from the wurtzite GaAs nanowire is perpendiculary polarized to the nanowire axis. The result indicates that the crystal phase, through the optical selection rules, has significant effect on the polarization of the PL from NWs besides the dielectric mismatch. The analysis of the PL results based on the electronic structure of these nanowires supports the correlation between the crystal phase and the PL emission.

  15. Modeling of photoluminescence in laser-based lighting systems

    Science.gov (United States)

    Chatzizyrli, Elisavet; Tinne, Nadine; Lachmayer, Roland; Neumann, Jörg; Kracht, Dietmar

    2017-12-01

    The development of laser-based lighting systems has been the latest step towards a revolution in illumination technology brought about by solid-state lighting. Laser-activated remote phosphor systems produce white light sources with significantly higher luminance than LEDs. The weak point of such systems is often considered to be the conversion element. The high-intensity exciting laser beam in combination with the limited thermal conductivity of ceramic phosphor materials leads to thermal quenching, the phenomenon in which the emission efficiency decreases as temperature rises. For this reason, the aim of the presented study is the modeling of remote phosphor systems in order to investigate their thermal limitations and to calculate the parameters for optimizing the efficiency of such systems. The common approach to simulate remote phosphor systems utilizes a combination of different tools such as ray tracing algorithms and wave optics tools for describing the incident and converted light, whereas the modeling of the conversion process itself, i.e. photoluminescence, in most cases is circumvented by using the absorption and emission spectra of the phosphor material. In this study, we describe the processes involved in luminescence quantum-mechanically using the single-configurational-coordinate diagram as well as the Franck-Condon principle and propose a simulation model that incorporates the temperature dependence of these processes. Following an increasing awareness of climate change and environmental issues, the development of ecologically friendly lighting systems featuring low power consumption and high luminous efficiency is imperative more than ever. The better understanding of laser-based lighting systems is an important step towards that aim as they may improve on LEDs in the near future.

  16. Photoluminescence and electroluminescence from Ge/strained GeSn/Ge quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chung-Yi; Chang, Chih-Chiang [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan (China); Huang, Chih-Hsiung; Huang, Shih-Hsien [Department of Electrical Engineering, Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liu, C. W., E-mail: chee@cc.ee.ntu.edu.tw [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan (China); Department of Electrical Engineering, Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); National Nano Device Labs, Hsinchu 30077, Taiwan (China); Huang, Yi-Chiau; Chung, Hua; Chang, Chorng-Ping [Applied Materials Inc., Sunnyvale, California 94085 (United States)

    2016-08-29

    Ge/strained GeSn/Ge quantum wells are grown on a 300 mm Si substrate by chemical vapor deposition. The direct bandgap emission from strained GeSn is observed in the photoluminescence spectra and is enhanced by Al{sub 2}O{sub 3}/SiO{sub 2} passivation due to the field effect. The electroluminescence of the direct bandgap emission of strained GeSn is also observed from the Ni/Al{sub 2}O{sub 3}/GeSn metal-insulator-semiconductor tunneling diodes. Electroluminescence is a good indicator of GeSn material quality, since defects in GeSn layers degrade the electroluminescence intensity significantly. At the accumulation bias, the holes in the Ni gate electrode tunnel to the strained n-type GeSn layer through the ultrathin Al{sub 2}O{sub 3} and recombine radiatively with electrons. The emission wavelength of photoluminescence and electroluminescence can be tuned by the Sn content.

  17. Defect-Induced Photoluminescence Enhancement and Corresponding Transport Degradation in Individual Suspended Carbon Nanotubes

    Science.gov (United States)

    Wang, Bo; Shen, Lang; Yang, Sisi; Chen, Jihan; Echternach, Juliana; Dhall, Rohan; Kang, DaeJin; Cronin, Stephen

    2018-05-01

    This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. The utilization of defects in carbon nanotubes to improve their photoluminescence efficiency has become a widespread study of the realization of efficient light-emitting devices. Here, we report a detailed comparison of the defects in nanotubes (quantified by Raman spectroscopy) and photoluminescence (PL) intensity of individual suspended carbon nanotubes (CNTs). We also evaluate the impact of these defects on the electron or hole transport in the nanotubes, which is crucial for the ultimate realization of optoelectronic devices. We find that brightly luminescent nanotubes exhibit a pronounced D-band in their Raman spectra, and vice versa, dimly luminescent nanotubes exhibit almost no D-band. Here, defects are advantageous for light emission by trapping excitons, which extend their lifetimes. We quantify this behavior by plotting the PL intensity as a function of the ID /IG -band Raman intensity ratio, which exhibits a Lorentzian distribution peaked at ID /IG=0.17 . For CNTs with a ID /IG ratio >0.25 , the PL intensity decreases, indicating that above some critical density, nonradiative recombination at defect sites dominates over the advantages of exciton trapping. In an attempt to fabricate optoelectronic devices based on these brightly luminescent CNTs, we transfer these suspended CNTs to platinum electrodes and find that the brightly photoluminescent nanotubes exhibit nearly infinite resistance due to these defects, while those without bright photoluminescence exhibit finite resistance. These findings indicate a potential limitation in the use of brightly luminescent CNTs for optoelectronic applications.

  18. Temperature dependence of photoluminescence from submonolayer deposited InGaAs/GaAs quantum dots

    DEFF Research Database (Denmark)

    Xu, Zhangcheng; Leosson, K.; Birkedal, Dan

    2002-01-01

    The temperature dependence of photoluminescence (PL) from self-assembled InGaAs quantum dots (QD's) grown by submonolayer deposition mode (non-SK mode), is investigated. It is found that the PL spectra are dominated by the ground-state transitions at low temperatures, but increasingly...... by the excited-state transitions at higher temperatures. The emission linewidth of the ground-state transitions of QDs ensembles first decreases and then increases with the increase of temperature, which results from the carrier transfer between dots via barrier states....

  19. Blue-green and red photoluminescence in CaTiO3:Sm

    International Nuclear Information System (INIS)

    Figueiredo, Alberthmeiry T. de; Longo, Valeria M.; Lazaro, Sergio de; Mastelaro, Valmor R.; De Vicente, Fabio S.; Hernandes, Antonio C.; Siu Li, Maximo; Varela, Jose A.; Longo, Elson

    2007-01-01

    Blue-green and red photoluminescence (PL) emission in structurally disordered CaTiO 3 :Sm (CT:Sm) powders was observed at room temperature with laser excitation at 350.7 nm. The perovskite-like titanate CT:Sm powders prepared by a soft chemical processing at different temperatures of annealing were structurally characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES). The results indicate that the generation of the broad PL band is related to order-disorder degree in the perovskite-like structure

  20. Nonlinear behavior of photoluminescence from silicon particles under two-photon excitation

    International Nuclear Information System (INIS)

    Xu Xingsheng; Yokoyama, Shiyoshi

    2011-01-01

    Two-photon excited fluorescence (TPEF) under continuous-wave excitation from silicon particles produced by a pulsed laser is investigated. Spectra and images of TPEF from silicon particles are studied under different excitation intensities and operation modes (continuous wave or pulse). It is found that the photoluminescence depends superlinearly on the excitation intensity and that the spectral shape and peaks vary with different silicon particles. The above phenomena show the nonlinear behavior of TPEF from silicon particles, and stimulated emission is a possible process.

  1. Tunable photoluminescent metal-organic-frameworks and method of making the same

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina M.; Sava Gallis, Dorina Florentina; Rohwer, Lauren E.S.

    2017-08-22

    The present disclosure is directed to new photoluminescent metal-organic frameworks (MOFs). The newly developed MOFs include either non rare earth element (REE) transition metal atoms or limited concentrations of REE atoms, including: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Ru, Ag, Cd, Sn, Sb, Ir, Pb, Bi, that are located in the MOF framework in site isolated locations, and have emission colors ranging from white to red, depending on the metal concentration levels and/or choice of ligand.

  2. Synthesis, crystal structure, and photoluminescence of a lithium isothiocyanate compound with 18-crown-6

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shan; Fu, Bo; Zhao, Zhen; Liu, Xi [Chongqing Normal Univ. (China). Chongqing Key Lab. of Inorganic Functional Materials

    2018-04-01

    The investigation of the supramolecular interactions between the lithium isothiocyanate salt and 18-crown-6 (18C-6) in commercial tetrahydrofuran leads to the formation of a lithium compound, LiNCS(H{sub 2}O)(18C-6) (1). In the crystal structure the asymmetric unit contains two similar LiNCS(H{sub 2}O)(18C-6) molecules. Solid-state photoluminescence experiments have shown that compound 1 emits violet luminescence, and its possible emission mechanism was investigated in detail based on theoretical calculations.

  3. Remarkably enhanced photoluminescence of hexagonal GdPO4·nH2O:Eu with decreasing size

    International Nuclear Information System (INIS)

    Lu Shaozhe; Zhang Jiahua; Zhang Jishen; Zhao Haifeng; Luo Yongshi; Ren Xinguang

    2010-01-01

    The hexagonal rhabdophane-type GdPO 4 hydrate (GdPO 4 ·nH 2 O) was synthesized via a simple hydrothermal process. The size and morphology of the products can be tunable by adjusting the pH of reaction systems through the addition of aqueous NaOH. The nanorods with a width of 50-100 nm and a length of about 1 μm were obtained in the absence of NaOH (pH = 2), while a significant reduction of size (width: ∼ 10 nm, length: ∼ 50 nm) was observed for the product synthesized in the presence of NaOH (pH = 10). Surprisingly, the small-sized product exhibits a remarkably enhanced photoluminescence quantum yield and long excited state lifetime in comparison with those of the large-sized product. This abnormal luminescence phenomenon is discussed and explained. The EDS and XPS measurements revealed the presence of Na + in the small-sized samples. These Na + cations were probably bonded to the surface O 2- dangling bonds, which thus reduces the number of surface defects that usually serve as the nonradiative energy transfer center channels. A considerable reduction of surface defect centers results in the increase of the emission efficiency and excited state lifetime in a small-sized sample. Obviously, the controlled synthesis of rare-earth-doped nanoparticles with a small size, but with relatively strong luminescence, is significant for their applications in the areas of technologies including optoelectronics, sensing and bioimaging.

  4. Annealing impact on the structural and photoluminescence properties of ZnO thin films on Ag substrates

    International Nuclear Information System (INIS)

    Xu, Linhua; Zheng, Gaige; Lai, Min; Pei, Shixin

    2014-01-01

    Graphical abstract: The Gaussian fitting indicates that the PL spectra of the ZnO thin films include four emission peaks which are centered at 380, 520, 570 and 610 nm, respectively. The ZnO thin film deposited on an Ag substrate shows a stronger green emission and a weaker UV emission than the ZnO thin film directly deposited on a Si substrate annealed at 400 °C. With the rise of annealing temperature, the visible emission intensity and wavelength are largely changed. Highlights: • ZnO thin films have been prepared on Ag substrates by sol–gel method. • The Ag substrates have a great effect on the photoluminescence of ZnO thin films. • All the films exhibit three visible emission bands including green, yellow and red. • Annealing causes a large change of the visible emission intensity and wavelength. -- Abstract: In this work, ZnO thin films were prepared by sol–gel method on Ag substrates. The structural and optical properties of the films annealed at different temperatures were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence, respectively. The results of XRD showed that all the ZnO thin films had a wurtzite phase and were preferentially oriented along the c-axis direction. The sample annealed at 400 °C exhibited better crystalline quality than the ZnO thin film directly deposited on a Si substrate annealed at the same temperature. The photoluminescence spectra showed that ZnO thin films had an ultraviolet emission band and three visible emission bands including green, yellow and red band. The sample annealed at 400 °C exhibited a stronger green emission and a weaker ultraviolet emission compared with the ZnO thin film deposited on a Si substrate annealed at the same temperature. The difference of the luminescence properties was thought to be originated from different substrates. As for the ZnO films on Ag substrates, the increase of annealing temperature led to different changes of visible emissions

  5. Structural and photoluminescence characterization of SnO{sub 2}: F thin films deposited by advanced spray pyrolysis technique at low substrate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shewale, P.S. [Thin Film Physics Laboratory, Department of Electronics, Shivaji University, Kolhapur 416004 (India); Ung Sim, Kyu; Kim, Ye-bin; Kim, J.H. [Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Buk-Gu, Gwangju 500757 (Korea, Republic of); Moholkar, A.V. [Department of Physics, Shivaji University, Kolhapur 416004 (India); Uplane, M.D., E-mail: mdu_eln@unishivaji.ac.in [Thin Film Physics Laboratory, Department of Electronics, Shivaji University, Kolhapur 416004 (India)

    2013-07-15

    Fluorine doped tin oxide (FTO) thin films were deposited on glass substrates, at different substrate temperatures using advanced spray pyrolysis technique. X-ray diffraction studies showed that the crystallinity of the thin films increased with increasing substrate temperature. FESEM and AFM studies support the conclusions drawn from X-ray diffraction studies. X-ray photoelectron studies confirm oxygen deficiency in formation of the FTO nanocrystallites. The photoluminescence of the FTO films were investigated. It was found that, room temperature photoluminescence spectra are dominated by oxygen vacancies and exhibit a rich violet photoluminescence band about ∼404 nm with an extensively feeble red emission about 700 nm. The Photoluminescence intensity varies with the substrate temperature. The photoemission position is observed to be independent of substrate temperature. -- Highlights: ► Photoluminescent FTO thin films were deposited at low substrate temperatures. ► Influence of substrate temperature on the PL characteristics was studied. ► The samples are polycrystalline with a cassiterite tetragonal crystal structure. ► The room temperature UV/violet PL emission was dominated by the oxygen vacancies. ► PL efficiency is optimum at 613 K substrate temperature.

  6. Nanophosphor CaSO4:Eu2+ for photoluminescence liquid crystal display (PLLCD)

    Science.gov (United States)

    Patle, Anita; Patil, R. R.; Moharil, S. V.

    2018-05-01

    In this work PL enhancement of CaSO4:Eu2+ nanophosphor which was synthesized with 0.01M molarity by co-precipitation method is presented. Synthesized phosphor was characterized by XRD, SEM, TEM and PL measurements. Average particle size is found to be in the range 80-100nm with Hexagonal morphology and PL studies showed emission peaks at 380nm, when samples were excited by 254nm. The observed PL emission is characteristic emission of Eu2+ similar to that observed in bulk CaSO4:Eu2. However under identical condition it is observed that intensity of emission get enhanced for 0.01M size which is doubled to that of 0.1M with similar emission at 380nm. A phosphor with narrow emission band around 390 nm is desirable, since at this wavelength the transmission of standard glass, polarizing plastic, other coating and LCD material is at acceptable level. Strong Eu2+ emission is observed in CaSO4:Eu nanophosphor which finds applications for PLLCD (photoluminescent liquid crystal display).

  7. Homogeneous Emission Line Broadening in the Organo Lead Halide Perovskite CH3NH3PbI3-xClx.

    Science.gov (United States)

    Wehrenfennig, Christian; Liu, Mingzhen; Snaith, Henry J; Johnston, Michael B; Herz, Laura M

    2014-04-17

    The organic-inorganic hybrid perovskites methylammonium lead iodide (CH3NH3PbI3) and the partially chlorine-substituted mixed halide CH3NH3PbI3-xClx emit strong and broad photoluminescence (PL) around their band gap energy of ∼1.6 eV. However, the nature of the radiative decay channels behind the observed emission and, in particular, the spectral broadening mechanisms are still unclear. Here we investigate these processes for high-quality vapor-deposited films of CH3NH3PbI3-xClx using time- and excitation-energy dependent photoluminescence spectroscopy. We show that the PL spectrum is homogenously broadened with a line width of 103 meV most likely as a consequence of phonon coupling effects. Further analysis reveals that defects or trap states play a minor role in radiative decay channels. In terms of possible lasing applications, the emission spectrum of the perovskite is sufficiently broad to have potential for amplification of light pulses below 100 fs pulse duration.

  8. The relation between photoluminescence properties and gas pressure with [0001] InGaN single quantum well systems

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, Toshiaki [Department of Nanosystem Sciences, Yokohama City University, Yokohama 236-0027 (Japan); Alfieri, Giovanni; Kawakami, Yoichi [Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-katsura, Nishikyo, Kyoto 615-8510 (Japan); Micheletto, Ruggero, E-mail: ruggero@yokohama-cu.ac.jp [Department of Nanosystem Sciences, Yokohama City University, Yokohama 236-0027 (Japan)

    2017-01-15

    Highlights: • Photoluminescence of InGaN device is variable, there is no clear explanation for this. • We perform an ad-hoc absorption procedure, found that gases on the surface reduce emission. • We found that variability is related to the pressure of the gas in which the sample is immersed. • We point out the role of oxygen as major player in the reduction of photoluminescence. • A model is proposed and explains successfully the dynamical optical processes observed. - Abstract: We show for the first time that photoluminescence of InGaN single quantum wells (SQW) devices is related to the gas pressure in which the sample is immersed, also we give a model of the phenomena to suggest a possible cause. Our model shows a direct relation between experimental behavior and molecular coverage dynamics. This strongly suggests that the driving force of photoluminescence decrease is oxygen covering the surface of the device with a time dynamics that depends on the gas pressure. This aims to contribute to the understanding of the physical mechanism of the so-called optical memory effect and blinking phenomenon observed in these devices.

  9. Photoluminescence of self-organized perylene bisimide polymers

    NARCIS (Netherlands)

    Neuteboom, E.E.; Meskers, S.C.J.; Meijer, E.W.; Janssen, R.A.J.

    2004-01-01

    Three polymers consisting of alternating perylene bisimide chromophores and flexible polytetrahydrofuran segments of different length have been studied using absorption and (time-resolved) photoluminescence spectroscopy. In o-dichlorobenzene, the chromophores self organize to form H-like aggregates.

  10. Photoluminescent carbogenic nanoparticles directly derived from crude biomass

    KAUST Repository

    Krysmann, Marta J.; Kelarakis, Antonios; Giannelis, Emmanuel P.

    2012-01-01

    We present an environmentally benign, energy efficient and readily scalable approach to synthesize photoluminescent carbogenic nanoparticles directly from soft tissue biomass. Our approach relies on the pyrolytic decomposition of grass that gives

  11. Impact of light polarization on photoluminescence intensity and quantum efficiency in AlGaN and AlInGaN layers

    Science.gov (United States)

    Netzel, C.; Knauer, A.; Weyers, M.

    2012-12-01

    We analyzed emission intensity, quantum efficiency, and emitted light polarization of c-plane AlGaN and AlInGaN layers (λ = 320-350 nm) by temperature dependent photoluminescence. Low indium content in AlInGaN structures causes a significant intensity increase by change of the polarization of the emitted light. Polarization changes from E ⊥ c to E ‖ c with increasing aluminum content. It switches back to E ⊥ c with the incorporation of indium. The polarization degree decreases with temperature. This temperature dependence can corrupt internal quantum efficiency determination by temperature dependent photoluminescence.

  12. Photoluminescent carbogenic nanoparticles directly derived from crude biomass

    KAUST Repository

    Krysmann, Marta J.

    2012-01-01

    We present an environmentally benign, energy efficient and readily scalable approach to synthesize photoluminescent carbogenic nanoparticles directly from soft tissue biomass. Our approach relies on the pyrolytic decomposition of grass that gives rise to the formation of well-defined nanoparticles. The carbogenic nanoparticles can be readily surface modified, generating a series of highly selective photoluminescent materials that exhibit remarkable stability upon prolonged exposure to aggressive, high-temperature, high-salinity environment. © 2012 The Royal Society of Chemistry.

  13. Using quantum dot photoluminescence for load detection

    Science.gov (United States)

    Moebius, M.; Martin, J.; Hartwig, M.; Baumann, R. R.; Otto, T.; Gessner, T.

    2016-08-01

    We propose a novel concept for an integrable and flexible sensor capable to visualize mechanical impacts on lightweight structures by quenching the photoluminescence (PL) of CdSe quantum dots. Considering the requirements such as visibility, storage time and high optical contrast of PL quenching with low power consumption, we have investigated a symmetrical and an asymmetrical layer stack consisting of semiconductor organic N,N,N',N'-Tetrakis(3-methylphenyl)-3,3'-dimethylbenzidine (HMTPD) and CdSe quantum dots with elongated CdS shell. Time-resolved series of PL spectra from layer stacks with applied voltages of different polarity and simultaneous observation of power consumption have shown that a variety of mechanisms such as photo-induced charge separation and charge injection, cause PL quenching. However, mechanisms such as screening of external field as well as Auger-assisted charge ejection is working contrary to that. Investigations regarding the influence of illumination revealed that the positive biased asymmetrical layer stack is the preferred sensor configuration, due to a charge carrier injection at voltages of 10 V without the need of coincident illumination.

  14. Using quantum dot photoluminescence for load detection

    Directory of Open Access Journals (Sweden)

    M. Moebius

    2016-08-01

    Full Text Available We propose a novel concept for an integrable and flexible sensor capable to visualize mechanical impacts on lightweight structures by quenching the photoluminescence (PL of CdSe quantum dots. Considering the requirements such as visibility, storage time and high optical contrast of PL quenching with low power consumption, we have investigated a symmetrical and an asymmetrical layer stack consisting of semiconductor organic N,N,N′,N′-Tetrakis(3-methylphenyl-3,3′-dimethylbenzidine (HMTPD and CdSe quantum dots with elongated CdS shell. Time-resolved series of PL spectra from layer stacks with applied voltages of different polarity and simultaneous observation of power consumption have shown that a variety of mechanisms such as photo-induced charge separation and charge injection, cause PL quenching. However, mechanisms such as screening of external field as well as Auger-assisted charge ejection is working contrary to that. Investigations regarding the influence of illumination revealed that the positive biased asymmetrical layer stack is the preferred sensor configuration, due to a charge carrier injection at voltages of 10 V without the need of coincident illumination.

  15. Solvothermal tuning of photoluminescent graphene quantum dots: from preparation to photoluminescence mechanism

    Science.gov (United States)

    Qi, Bao-Ping; Zhang, Xiaoru; Shang, Bing-Bing; Xiang, Dongshan; Zhang, Shenghui

    2018-02-01

    Solvothermal synthesis was employed to tune the surface states of graphene quantum dots (GQDs). Two series of GQDs with the particle sizes from 2.6 to 4.5 nm were prepared as follows: (I) GQDs with the same size but different oxygen degrees; (II) GQDs with different core sizes but the similar surface chemistry. Both the large sizes and the high surface oxidation degrees led to the redshift photoluminescence (PL) of GQDs. Electrochemiluminescence (ECL) spectra from two series of GQDs were all in accordance with their PL spectra, respectively, which provided good evidence for the conjugated structures in GQDs responsible for PL. [Figure not available: see fulltext.

  16. Investigation of the photoluminescence properties of thermochemically synthesized CdS nanocrystals

    Directory of Open Access Journals (Sweden)

    M. Molaei

    2011-03-01

    Full Text Available In this work we have synthesized CdS nanocrystals with thermochemical method. CdSO4 and Na2S2O3 were used as the precursors and thioglycolic acid (TGA was used as capping agent molecule. The structure and optical property of the nanocrystals were characterized by means of XRD, TEM, UV-visible optical spectroscopy and photoluminescence (PL. X-ray diffraction (XRD and TEM analyses demonstrated hexagonal phase CdS nanocrystals with an average size around 2 nm. Synthesized nanocrystals exhibited band gap of about 3.2 eV and showed a broad band emission from 400-750 nm centered at 504 nm with a (0.27, 0.39 CIE coordinate. This emission can be attributed to recombination of an electron in conduction band with a hole trapped in Cd vacancies near to the valance band of CdS. The best attained photoluminescence quantum yield of the nanocrystals was about 12%, this amount is about 20 times higher than that for thioglycerol (TG capped CdS nanocrystals.

  17. Hydrothermal synthesis and characteristic photoluminescence of Er-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tuan, Pham Van; Hieu, Le Trung; Nga, La Quynh [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Dung, Nguyen Duc [Advanced Institute of Science and Technology, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Khiem, Tran Ngoc, E-mail: khiem@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam)

    2016-11-15

    We report the characteristic photoluminescence (PL) spectra of erbium ion (Er{sup 3+})-doped tin dioxide (SnO{sub 2})nanoparticles. The materials were prepared via hydrothermal method at 180 °C with in 20 h by using various Er{sup 3+} ion concentrations ranging from 0.0 to 1.0 at%. After the synthesis, the materials were characterized through X-ray diffraction and high-resolution transmission electron microscopy. Crystallite SnO{sub 2} and its average particle diameter of approximately 5 nm did not change with Er{sup 3+} ion dopant concentration. Photoluminescence spectra showed the characteristic light emission from the Er{sup 3+} ions. The PL excitation spectra referred to an efficient energy transfer to Er{sup 3+} ions in the presence of SnO{sub 2}nanoparticles. The most intense Er-related emission of SnO{sub 2}:Er{sup 3+} nanoparticles in near infrared region was found in samples containing an Er{sup 3+} ion concentration of 0.25 at%. Although the absorption bandgaps of the materials were identified at approximately 3.8 eV, we found that efficient excitation comes with low excitation energy band edge. Excitation is possibly involved in shallow defects in SnO{sub 2} nanoparticles.

  18. Shape controlled synthesis of CaMoO4 thin films and their photoluminescence property

    International Nuclear Information System (INIS)

    Marques, Ana Paula de Azevedo; Longo, Valeria M.; Melo, Dulce M.A. de; Pizani, Paulo S.; Leite, Edson R.; Varela, Jose Arana; Longo, Elson

    2008-01-01

    CaMoO 4 (CMO) disordered and ordered thin films were prepared by the complex polymerization method (CPM). The films were annealed at different temperatures and time in a conventional resistive furnace (RF) and in a microwave (MW) oven. The microstructure and surface morphology of the structure were monitored by atomic force microscopy (AFM) and high-resolution scanning electron microscopy (HRSEM). Order and disorder were characterized by X-ray diffraction (XRD) and optical reflectance. A strong photoluminescence (PL) emission was observed in the disordered thin films and was attributed to complex cluster vacancies. The experimental results were compared with density functional and Hartree-Fock calculations. - Graphical abstract: CaMoO 4 thin films were prepared by the complex polymerization method (CPM). The films were annealed at different temperatures and time in a conventional resistive furnace and in a microwave oven. A strong photoluminescence emission was observed in the disordered thin films and was attributed to complex cluster vacancies. The experimental results were confirmed by high level first principle calculations

  19. Facile synthesis of S, N co-doped carbon dots and investigation of their photoluminescence properties.

    Science.gov (United States)

    Zhang, Yue; He, Junhui

    2015-08-21

    A facile one-pot approach to prepare photoluminescent carbon dots (CDs) was developed through hydrothermal treatment of cysteine and citric acid. The obtained CDs show stable and bright blue emission with a quantum yield of 54% and an average lifetime of 11.61 ns. Moreover, the two-photon induced upconversion fluorescence of the CDs was observed and demonstrated. Interestingly, both down and up conversion fluorescence of the CDs show excitation-independent emission, which is quite different from most of the previously reported CDs. Ultrafast spectroscopy was also employed here to study the photoluminescence (PL) properties of the CDs. After characterization using various spectroscopic techniques, a unique PL mechanism for the as-prepared CDs' fluorescence was proposed accordingly. In addition, the influence of various metal ions on the CD fluorescence was examined and no quenching phenomena were observed. Meanwhile, gold nanoparticles (Au NPs) were found to be good quenchers of CD fluorescence and their quenching behavior was fitted to the Stern-Volmer equation. This provides new opportunities for fluorescence sensor designs and light energy conversion applications. Finally, the as-prepared CDs were inkjet-printed to form a desirable pattern, which is useful for fluorescent patterns, and anti-counterfeiting labeling.

  20. Photoluminescence wavelength variation of monolayer MoS2 by oxygen plasma treatment

    International Nuclear Information System (INIS)

    Kim, Min Su; Nam, Giwoong; Park, Seki; Kim, Hyun; Han, Gang Hee; Lee, Jubok; Dhakal, Krishna P.; Leem, Jae-Young; Lee, Young Hee; Kim, Jeongyong

    2015-01-01

    We performed nanoscale confocal photoluminescence (PL), Raman, and absorption spectral imaging measurements to investigate the optical and structural properties of molybdenum disulfide (MoS 2 ) monolayers synthesized by chemical vapor deposition method and subjected to oxygen plasma treatment for 10 to 120 s under high vacuum (1.3 × 10 −3 Pa). Oxygen plasma treatment induced red shifts of ~ 20 nm in the PL emission peaks corresponding to A and B excitons. Similarly, the peak positions corresponding to A and B excitons of the absorption spectra were red-shifted following oxygen plasma treatment. Based on the confocal PL, absorption, and Raman microscopy results, we suggest that the red-shifting of the A and B exciton peaks originated from shallow defect states generated by oxygen plasma treatment. - Highlights: • Effects of oxygen plasma on optical properties of monolayer MoS 2 were investigated. • Confocal photoluminescence, Raman, and absorption spectral maps are presented. • Wavelength tuning up to ~ 20 nm for the peak emission wavelength was achieved

  1. Photoluminescence wavelength variation of monolayer MoS{sub 2} by oxygen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Su [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Nam, Giwoong [Department of Nanoscience & Engineering, Inje University, Gimhae 621-749 (Korea, Republic of); Park, Seki; Kim, Hyun [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Han, Gang Hee [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Jubok; Dhakal, Krishna P. [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Leem, Jae-Young [Department of Nanoscience & Engineering, Inje University, Gimhae 621-749 (Korea, Republic of); Lee, Young Hee [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Jeongyong, E-mail: j.kim@skku.edu [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-09-01

    We performed nanoscale confocal photoluminescence (PL), Raman, and absorption spectral imaging measurements to investigate the optical and structural properties of molybdenum disulfide (MoS{sub 2}) monolayers synthesized by chemical vapor deposition method and subjected to oxygen plasma treatment for 10 to 120 s under high vacuum (1.3 × 10{sup −3} Pa). Oxygen plasma treatment induced red shifts of ~ 20 nm in the PL emission peaks corresponding to A and B excitons. Similarly, the peak positions corresponding to A and B excitons of the absorption spectra were red-shifted following oxygen plasma treatment. Based on the confocal PL, absorption, and Raman microscopy results, we suggest that the red-shifting of the A and B exciton peaks originated from shallow defect states generated by oxygen plasma treatment. - Highlights: • Effects of oxygen plasma on optical properties of monolayer MoS{sub 2} were investigated. • Confocal photoluminescence, Raman, and absorption spectral maps are presented. • Wavelength tuning up to ~ 20 nm for the peak emission wavelength was achieved.

  2. Correlation between reflectance and photoluminescent properties of al-rich ZnO nano-structures

    Science.gov (United States)

    Khan, Firoz; Baek, Seong-Ho; Ahmad, Nafis; Lee, Gun Hee; Seo, Tae Hoon; Suh, Eun-kyung; Kim, Jae Hyun

    2015-05-01

    Al rich zinc oxide nano-structured films were synthesized using spin coating sol-gel technique. The films were annealed in oxygen ambient in the temperature range of 200-700 °C. The structural, optical, and photoluminescence (PL) properties of the films were studied at various annealing temperatures using X-ray diffraction spectroscopy, field emission scanning electron microscopy, photoluminescence emission spectra measurement, and Raman and UV-Vis spectroscopy. The optical band gap was found to decrease with the increase of the annealing temperature following the Gauss Amp function due to the confinement of the exciton. The PL peak intensity in the near band region (INBE) was found to increase with the increase of the annealing temperature up to 600 °C, then to decrease fast to a lower value for the annealing temperature of 700 °C due to crystalline quality. The Raman peak of E2 (low) was red shifted from 118 cm-1 to 126 cm-1 with the increase of the annealing temperature. The intensity of the second order phonon (TA+LO) at 674 cm-1 was found to decrease with the increase of the annealing temperature. The normalized values of the reflectance and the PL intensity in the NBE region were highest for the annealing temperature of 600 °C. A special correlation was found between the reflectance at λ = 1000 nm and the normalized PL intensity in the green region due to scattering due to presence of grains.

  3. Photoluminescent BaMoO4 nanopowders prepared by complex polymerization method (CPM)

    International Nuclear Information System (INIS)

    Azevedo Marques, Ana Paula de; Melo, Dulce M.A. de; Paskocimas, Carlos A.; Pizani, Paulo S.; Joya, Miryam R.; Leite, Edson R.; Longo, Elson

    2006-01-01

    The BaMoO 4 nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO 4 powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO 4 at 300 deg. C was disordered. At 400 deg. C and higher temperature, BaMoO 4 crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 deg. C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 deg. C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO 4 nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO 4 nanopowders suggested that this material is a highly promising candidate for photoluminescent applications

  4. Photoluminescence in Carborane-Stilbene Triads: A Structural, Spectroscopic, and Computational Study.

    Science.gov (United States)

    Cabrera-González, Justo; Viñas, Clara; Haukka, Matti; Bhattacharyya, Santanu; Gierschner, Johannes; Núñez, Rosario

    2016-09-12

    A set of triads in which o- and m-carborane clusters are bonded to two stilbene units through Ccluster -CH2 bonds was synthesized, and their structures were confirmed by X-ray diffraction. A study on the influence of the o- and m- isomers on the absorption and photoluminescence properties of the stilbene units in solution revealed no charge-transfer contributions in the lowest excited state, as confirmed by (TD)DFT calculations. The presence of one or two B-I groups in m-carborane derivatives does not affect the emission properties of the stilbenes in solution, probably due to the rather large distance between the iodo substituents and the fluorophore. Nevertheless, a significant redshift of the photoluminescence (PL) emission maximum in the solid state (thin films and powder samples) compared to solution was observed; this can be traced back to PL sensitization, most probably due to more densely packed stilbene moieties. Remarkably, the PL absolute quantum yields of powder samples are significantly higher than those in solution, and this was attributed to the restricted environment and the aforementioned sensitization. Thus, the bonding of the carborane clusters to two stilbene units preserves their PL behavior in solution, but produces significant changes in the solid state. Furthermore, iodinated species can be considered to be promising precursors for theranostic agents in which both imaging and therapeutic functions could possibly be combined. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Germanium nanoislands grown by radio frequency magnetron sputtering: Annealing time dependent surface morphology and photoluminescence

    International Nuclear Information System (INIS)

    Samavati, Alireza; Othaman, Z.; Ghoshal, S. K.; Amjad, R. J.

    2013-01-01

    Structural and optical properties of ∼ 20 nm Ge nanoislands grown on Si(100) by radio frequency (rf) magnetron sputtering under varying annealing conditions are reported. Rapid thermal annealing at a temperature of 600°C for 30 s, 90 s, and 120 s are performed to examine the influence of annealing time on the surface morphology and photoluminescence properties. X-ray diffraction spectra reveal prominent Ge and GeO 2 peaks highly sensitive to the annealing time. Atomic force microscope micrographs of the as-grown sample show pyramidal nanoislands with relatively high-density 10 11 cm −2) ). The nanoislands become dome-shaped upon annealing through a coarsening process mediated by Oswald ripening. The room temperature photoluminescence peaks for both as-grown 3.29 eV) and annealed 3.19 eV) samples consist of high intensity and broad emission, attributed to the effect of quantum confinement. The red shift (∼0.10 eV) of the emission peak is attributed to the change in the size of the Ge nanoislands caused by annealing. Our easy fabrication method may contribute to the development of Ge nanostructure-based optoelectronics. (interdisciplinary physics and related areas of science and technology)

  6. Effect of proton irradiation on photoluminescent properties of PDMS-nanodiamond composites

    International Nuclear Information System (INIS)

    Borjanovic, Vesna; Hens, Suzanne; Shenderova, Olga; McGuire, Gary E; Lawrence, William G; Edson, Clark; Jaksic, Milko; Zamboni, Ivana; Vlasov, Igor

    2008-01-01

    Pure poly(dimethylsiloxane) (PDMS) films, PDMS-nanodiamond (ND) and pure nanodiamond powder were irradiated with 2 MeV protons under a variety of fluence and current conditions. Upon proton irradiation, these samples acquire a fluence-dependent photoluminescence (PL). The emission and excitation spectra, photostability and emission lifetime of the induced photoluminescence of PDMS and PDMS-ND samples are reported. Pure PDMS exhibits a noticeable stable blue PL, while the PDMS-ND composites exhibit a pronounced stable green PL under 425 nm excitation. The PL of PDMS-ND composites is much more prominent than that of pure PDMS or pure ND powder even when irradiated at higher doses. The origin of the significantly enhanced PL intensity for the proton-irradiated PDMS-ND composite is explained by the combination of enhanced intrinsic PL within ND particles due to ion-implantation-generated defects and by PL originating from structural transformations produced by protons at the nanodiamond/matrix interface.

  7. Effect of additionally introduced Zn and Eu dopants on the photoluminescence spectra of Er-Doped GaN crystals

    International Nuclear Information System (INIS)

    Mezdrogina, M. M.; Krivolapchuk, V. V.; Petrov, V. N.; Rodin, S. N.; Cherenkov, A. V.

    2006-01-01

    It is shown that the effect of dopants on the photoluminescence spectrum depends on the conductivity type of the initial GaN crystals. Sensitization of emission is observed in wurtzite p-GaN crystals doped with Er. The same effect was previously observed in such crystals doped with Eu and Zn. In n-type GaN crystals sequentially doped with Eu, Zn, and Er, emission is observed in the visible (λ = 360-440 and 530-560 nm) and IR (λ = 1.54 μm) spectral regions

  8. Laser induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} chalcogenide nano colloids

    Energy Technology Data Exchange (ETDEWEB)

    Tintu, R., E-mail: tintu_tillanivas@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India); Nampoori, V.P.N.; Radhakrishnan, P.; Thomas, Sheenu [International School of Photonics, Cochin University of Science and Technology, Cochin 689110 (India); Unnikrishnan, N.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India)

    2013-04-01

    We report the observation of two-photon induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} nano colloid solutions using frequency doubled Nd:YAG laser. Quadratic emission intensity dependence verifies the two photon absorption for the observed luminescence at an excitation of 532 nm. The optical band gap of the material is found to be tunable depending on the cluster size of the nano colloids. The cluster formation and the dependence of the cluster size with concentration were confirmed by the SEM analysis. Confocal imaging was done to confirm the emission from the clusters in the nano colloid solutions.

  9. Photoluminescence characterization of Dy3+ and Eu2+ ion in M5(PO4)3F (M = Ba, Sr, Ca) phosphors

    International Nuclear Information System (INIS)

    Nagpure, I.M.; Shinde, K.N.; Dhoble, S.J.; Kumar, Animesh

    2009-01-01

    Photoluminescence investigation of Eu and Dy activated phosphate based phosphors prepared by combustion synthesis, characterized by XRD (X-ray diffraction) and photoluminescence techniques, has been reported. PL excitation spectrum of M 5 (PO 4 ) 3 F:Dy phosphors shows the excitation peaks ranging from 300 to 400 nm due to 4f → 4f transitions of Dy 3+ ions. PL emission spectrum of Dy 3+ ion under 348 nm excitation gives PL emission at 482 nm (blue) due to 4 F 9/2 → 6 H 15/2 transitions, 574 nm (yellow) emission due to 4 F 9/2 → 6 H 13/2 transitions and 670 nm (red) due to 4 F 9/2 → 6 H 11/2 transitions, gives BYR (blue-yellow-red) emissions. The Eu 2+ broad band PL emission spectrum was observed in M 5 (PO 4 ) 3 F:Eu phosphor at 440 nm in the blue region of the spectrum due to 5d → 4f transition at 352 nm excitation. The 300-400 nm is Hg-free excitation (Hg excitation is 85% 254 nm wavelength of light and 15% other wavelengths), which is characteristic of solid-state lighting phosphors. Hence PL emission in divalent europium and trivalent dysprosium may be efficient photoluminescent materials for solid-state lighting phosphors.

  10. Structure and photoluminescence of films composed of carbon nanoflakes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi, E-mail: wangyi@cqut.edu.cn [College of Mechanical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054, P R China (China); Li, Lin [College of Chemistry, Chongqing Normal University, Chongqing 401331, P R China (China); Cheng, Qijin [School of Energy Research, Xiamen University, Xiamen 361005, P R China (China); He, Chunlin [Liaoning Provincial Key Laboratory of Advanced Materials, Shenyang University, Shenyang 110044, P R China (China)

    2015-05-15

    Carbon nanoflake films (CNFFs) were directly synthesized by plasma-enhanced hot filament chemical vapor deposition. The results of field emission scanning electron microscope, transmission electron microscope, micro-Raman spectroscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope indicate that the CNFFs are composed of bending carbon nanoflakes with the hydrocarbon and hydroxyl functional groups, and the carbon nanoflakes become thin in a long deposition time. The structural change of carbon nanoflakes is related to the formation of structural units and the aggregation of hydrocarbon radicals near the carbon nanoflakes. Moreover, the photoluminescence (PL) properties of CNFFs were studied in a Ramalog system and a PL spectroscope. The PL results indicate that the PL intensity of CNFFs is lowered with the increase of thickness of CNFFs. The lowering of PL intensity for the thick CNFFs originates from the effect of more dangling bonds in the CNFFs. In addition, we studied the structural difference of carbon nanoflakes grown by different CVD systems and the PL difference of carbon nanoflakes in different measurement systems. The results achieved here are important to control the growth and structure of graphene-based materials and fabricate the optoelectronic devices related to carbon-based materials. - Highlights: • Carbon nanoflake films (CNFFs) were synthesized by PEHFCVD. • The structure of CNFFs is related to the aggregation of carbon hydrocarbon radicals. • The PL intensity of CNFFs is lowered with the thickness increase of CNFFs. • The change of PL intensity of CNFFs is due to the dangling bonds in CNFFs. • The widening of PL bands of CNFFs results from the diversity of carbon nanofalkes.

  11. Effect of illumination on photoluminescence properties of porous silicon

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2008-11-01

    Porous silicon (PS) layers were formed by photo-electrochemical etching of both p-type and n-type single crystal wafers in HF based solution. During the etching process, the silicon wafer was illuminated by a halogen lamp light guided by an optical fiber through a monochromator or diode lasers at different power density and wavelengths (480,533,580 and 635 nm). The optical and structural properties of the prepared PS samples have been investigated by using temperature dependent photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, contact angle (CA) measurements, optical microscope and atomic force microscope (AFM). Beside the strong red-yellow PL band, a blue PL band has been observed only in the PS samples formed under the illumination with low power and short wavelengths (480-580 nm) light. In the near infrared (IR) spectral range, a new PL band at 850 nm was observed in p-type PS samples, which prepared under darkness or illumination with 635 nm of low power light. Temperature dependent PL measurements showed that, in contrast to the main IR PL band at around 1100 nm, the intensity of this new band increases on increasing the temperature. These changes in the PL properties was correlated with the illumination induced-structural and morphological modifications in the PS skeleton. In particular, the FTIR analysis showed that the chemical groups and bonds constituting the PS skeleton, such as, SiH, SiO bonds and silanol SiOH group play key role in deciding the PL emission intensity and blue shift. The study proved that the illumination parameters during the photo-electrochemical etching process can be utilized for tailoring a porous layer with novel optical and structural properties. (Authors)

  12. Effect of illumination on photoluminescence properties of porous silicon

    International Nuclear Information System (INIS)

    Naddaf, M.; Hamadeh, H.

    2009-01-01

    Porous silicon (PS) layers were formed by photo-electrochemical etching of both p-type and n-type single crystal wafers in HF based solution. During the etching process, the silicon wafer was illuminated by a halogen lamp light guided by an optical fiber through a monochromator or diode lasers at different power density and wavelengths (480,533,580 and 635 nm). The optical and structural properties of the prepared PS samples have been investigated by using temperature dependent photoluminescence (PL) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, contact angle (CA) measurements, optical microscope and atomic force microscope (AFM). Beside the strong red-yellow PL band, a blue PL band has been observed only in the PS samples formed under the illumination with low power and short wavelengths (480-580 nm) light. In the near infrared (IR) spectral range, a new PL band at 850 nm was observed in p-type PS samples, which prepared under darkness or illumination with 635 nm of low power light. Temperature dependent PL measurements showed that, in contrast to the main IR PL band at around 1100 nm, the intensity of this new band increases on increasing the temperature. These changes in the PL properties was correlated with the illumination induced-structural and morphological modifications in the PS skeleton. In particular, the FTIR analysis showed that the chemical groups and bonds constituting the PS skeleton, such as, SiH, SiO bonds and silanol SiOH group play key role in deciding the PL emission intensity and blue shift. The study proved that the illumination parameters during the photo-electrochemical etching process can be utilized for tailoring a porous layer with novel optical and structural properties. (Authors)

  13. Surface plasmon on topological insulator/dielectric interface enhanced ZnO ultraviolet photoluminescence

    Directory of Open Access Journals (Sweden)

    Zhi-Min Liao

    2012-06-01

    Full Text Available It has recently been predicted that the surface plasmons are allowed to exist on the interface between a topological insulator and vacuum. Surface plasmons can be employed to enhance the optical emission from various illuminants. Here, we study the photoluminescence properties of the ZnO/Bi2Te3 hybrid structures. Thin flakes of Bi2Te3, a typical three-dimensional topological insulator, were prepared on ZnO crystal surface by mechanical exfoliation method. The ultraviolet emission from ZnO was found to be enhanced by the Bi2Te3 thin flakes, which was attributed to the surface plasmon – photon coupling at the Bi2Te3/ZnO interface.

  14. Temperature-dependent photoluminescence analysis of ZnO nanowire array annealed in air

    Science.gov (United States)

    Sun, Yanan; Gu, Xiuquan; Zhao, Yulong; Wang, Linmeng; Qiang, Yinghuai

    2018-05-01

    ZnO nanowire arrays (NWAs) were prepared on transparent conducting fluorine doped tin oxide (FTO) substrates through a facile hydrothermal method, followed by a 500 °C annealing to improve their crystalline qualities and photoelectrochemical (PEC) activities. It was found that the annealing didn't change the morphology, but resulted in a significant reduction of the donor concentration. Temperature-dependent photoluminescence (PL) was carried out for a comprehensive analysis of the effect from annealing. Noteworthy, four dominant peaks were identified from the 10 K spectrum of a 500 °C annealed sample, and they were assigned to FX, D0X, (e, D0) and (e, D0) -1LO, respectively. Of them, the FX emission was only existed below 130 K, while the room-temperature (RT) PL spectrum was dominated by the D0X emission.

  15. Photoluminescence of acupoint 'Waiqiu' in human superficial fascia

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuan [Synchrotron Radiation Research Center, Department of Physics, Surface Physics Laboratory (State Key Laboratory) of Fudan University, Shanghai 200433 (China); Yan Xiaohui [Synchrotron Radiation Research Center, Department of Physics, Surface Physics Laboratory (State Key Laboratory) of Fudan University, Shanghai 200433 (China); Liu Chenglin [Synchrotron Radiation Research Center, Department of Physics, Surface Physics Laboratory (State Key Laboratory) of Fudan University, Shanghai 200433 (China); Dang Ruishan [Second Military Medical University, Shanghai 200433 (China); Zhang Xinyi [Synchrotron Radiation Research Center, Department of Physics, Surface Physics Laboratory (State Key Laboratory) of Fudan University, Shanghai 200433 (China) and Shanghai Research Center of Acupuncture and Meridian, Pudong, Shanghai 201203 (China)]. E-mail: xy-zhang@fudan.edu.cn

    2006-07-15

    The spectral characters of an acupuncture point named 'Waiqiu' in superficial fascia tissue have been studied by photoluminescence (PL) spectroscopy under the excitation of 457.9 nm. The PL around 'Waiqiu' acupuncture point consists of two sub-bands resulting from the flavin adenine dinucleotide (FAD) and phospholipids, and the porphyrins (including purine, isoxanthopterin and tryptophan), respectively. More emission due to FAD and phospholipids is found inside the acupuncture effect area of 'Waiqiu' than its marginal or outside acupuncture regions. The ratio of emission intensity of FAD and phospholipids to one of porphyrins gradually decreases along the direction away from the center of the acupuncture point. It implies that the component proportion changes between FAD, phospholipids and porphyrins around the 'Waiqiu' acupuncture point. We suggest that there might be a certain relationship between redox function of FAD and 'Waiqiu' acupuncture effect.

  16. Photoluminescence quenching processes by NO2 adsorption in ZnO nanostructured films

    Science.gov (United States)

    Cretı, A.; Valerini, D.; Taurino, A.; Quaranta, F.; Lomascolo, M.; Rella, R.

    2012-04-01

    The optical response by NO2 gas adsorption at different concentrations has been investigated, at room temperature, in ZnO nanostructured films grown by controlled vapor phase deposition. The variation (quenching) in the photoluminescence signal from excitonic and defects bands, due to the interactions between the oxidizing gas molecules and the sample surface, has been detected and dynamic responses and calibration curves as a function of gas concentration have been obtained and analyzed for each band. We showed that the sensing response results larger in excitonic band than in defect one and that the emission signal rises from two different quenchable and unquenchable states. A simple model was proposed in order to explain the quenching processes on the emission intensity and to correlate them to the morphological features of the samples. Finally, the reversibility of the quenching effects has also been tested at high gas concentration.

  17. 380 keV proton irradiation effects on photoluminescence of Eu-doped GaN

    International Nuclear Information System (INIS)

    Okada, Hiroshi; Nakanishi, Yasuo; Wakahara, Akihiro; Yoshida, Akira; Ohshima, Takeshi

    2008-01-01

    The effect of 380 keV proton irradiation on the photoluminescence (PL) properties has been investigated for undoped and Eu-doped GaN. As the proton irradiation exceeds 1x10 13 cm -2 , a drastic decrease of PL intensity of the near band-edge emission of undoped GaN was observed. On the other hand, for Eu-doped GaN, the PL emission corresponding to the 5 D 0 → 7 F 2 transition in Eu 3+ kept the initial PL intensity after the proton irradiation up to 1x10 14 cm -2 . Present results, together with our previous report on electron irradiation results, suggest that Eu-doped GaN is a strong candidate for light emitting devices in high irradiation environment

  18. Quenching of the surface-state-related photoluminescence in Ni-coated ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tang Yang [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences (China); Zhao Dongxu, E-mail: dxzhao2000@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhang Jiying; Shen Dezhen [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China)

    2010-11-01

    Nickel-coated ZnO nanowires (NWs) were fabricated by electrodepositing Ni particles on ZnO NW arrays. The morphological, magnetic, and photoluminescent properties of the Ni-coated ZnO NWs were investigated. The Ni particles were deposited on the ZnO NWs' surface along its length to form a Ni/ZnO shell-core structure. The Ni-coated ZnO NWs exhibited more isotropic characteristic than the electrodeposited Ni films owing to the isotropic sphere structure of the Ni particles. A strong ultraviolet emission can be obtained from the Ni-coated ZnO NWs, while the green emission related to surface states was quenched by the passivated layer.

  19. Quenching of the surface-state-related photoluminescence in Ni-coated ZnO nanowires

    International Nuclear Information System (INIS)

    Tang Yang; Zhao Dongxu; Zhang Jiying; Shen Dezhen

    2010-01-01

    Nickel-coated ZnO nanowires (NWs) were fabricated by electrodepositing Ni particles on ZnO NW arrays. The morphological, magnetic, and photoluminescent properties of the Ni-coated ZnO NWs were investigated. The Ni particles were deposited on the ZnO NWs' surface along its length to form a Ni/ZnO shell-core structure. The Ni-coated ZnO NWs exhibited more isotropic characteristic than the electrodeposited Ni films owing to the isotropic sphere structure of the Ni particles. A strong ultraviolet emission can be obtained from the Ni-coated ZnO NWs, while the green emission related to surface states was quenched by the passivated layer.

  20. Low-temperature growth and photoluminescence property of ZnS nanoribbons.

    Science.gov (United States)

    Zhang, Zengxing; Wang, Jianxiong; Yuan, Huajun; Gao, Yan; Liu, Dongfang; Song, Li; Xiang, Yanjuan; Zhao, Xiaowei; Liu, Lifeng; Luo, Shudong; Dou, Xinyuan; Mou, Shicheng; Zhou, Weiya; Xie, Sishen

    2005-10-06

    At a low temperature of 450 degrees C, ZnS nanoribbons have been synthesized on Si and KCl substrates by a simple chemical vapor deposition (CVD) method with a two-temperature-zone furnace. Zinc and sulfur powders are used as sources in the different temperature zones. X-ray diffraction (XRD), selected area electron diffraction (SEAD), and transmission electron microscopy (TEM) analysis show that the ZnS nanoribbons are the wurtzite structure, and there are two types-single-crystal and bicrystal nanoribbons. Photoluminescence (PL) spectrum shows that the spectrum mainly includes two parts: a purple emission band centering at about 390 nm and a blue emission band centering at about 445 nm with a weak green shoulder around 510 nm.

  1. Photoluminescence and cathodoluminescence properties of Y2O3:Eu nanophosphors prepared by combustion synthesis

    International Nuclear Information System (INIS)

    Vu, Nguyen; Kim Anh, Tran; Yi, Gyu-Chul; Strek, W.

    2007-01-01

    Eu-doped Y 2 O 3 nanophosphors were prepared using combustion synthesis. In this method, urea was employed as a fuel. The particle size was estimated to be in the range of 10-20 nm as determined by X-ray diffractometry and transmission electron microscopy. The photoluminescent and cathodoluminescent spectra are described by the well-known 5 D 0 →7 F J transition (J=0, 1, 2, etc.) of Eu 3+ ions with the strongest emission for J=2. The optical properties of nanophosphors were compared with commercial with an order of micrometer size. The effects of urea-to-metal nitrate molar ratio and the other synthesis conditions on the particle size and luminescent properties will be discussed in detail. The red emission of Eu-doped Y 2 O 3 nanophosphors is promising materials not only in high-resolution screen but also in telecomunication as well as in biosensor

  2. Improving the photoluminescence response of Er-Tm: Al2O3 films by Yb codoping

    International Nuclear Information System (INIS)

    Xiao Zhisong; Serna, R.; Afonso, C.N.; Cheng Guoan; Vickridge, I.

    2007-01-01

    Amorphous Al 2 O 3 films doped with Er, Tm and Yb have been prepared by pulsed laser deposition. A broadband emission in the range 1400-1700 nm with two peaks around 1540 and 1640 nm has been observed, both in the Er-Tm and Er-Tm-Yb codoped films. The Tm-related photoluminescence (PL) intensity at 1640 nm is enhanced when codoping with Yb thus suggesting the existence of multiple energy transfer processes from Yb to Er and Er to Tm. The Er-Tm-Yb codoped film exhibits a broadband emission with a full-width half-maximum of 184 nm similar to that of the film codoped with Tm and Er but having higher Tm to Er concentration ratio and higher PL lifetime values

  3. Polycrystalline Si nanoparticles and their strong aging enhancement of blue photoluminescence

    Science.gov (United States)

    Yang, Shikuan; Cai, Weiping; Zeng, Haibo; Li, Zhigang

    2008-07-01

    Nearly spherical polycrystalline Si nanoparticles with 20 nm diameter were fabricated based on laser ablation of silicon wafer immersed in sodium dodecyl sulfate aqueous solution. Such Si nanoparticles consist of disordered areas and ultrafine grains of 3 nm in mean size and exhibit significant photoluminescence in blue region. Importantly, aging at ambient air leads to continuing enhancement of the emission (more than 130 times higher in 16 weeks) showing stable and strong blue emission. This aging enhancement is attributed to progressive passivation of nonradiative Pb centers corresponding to silicon dangling bonds on the particles' surface. This study could be helpful in pushing Si into optoelectronic field and Si-based full color display, biomedical tagging, and flash memories.

  4. Tunable photoluminescence of CsPbBr3 perovskite quantum dots for light emitting diodes application

    Science.gov (United States)

    Chen, Weiwei; Xin, Xing; Zang, Zhigang; Tang, Xiaosheng; Li, Cunlong; Hu, Wei; Zhou, Miao; Du, Juan

    2017-11-01

    All-inorganic cesium lead halide (CsPbBr3) perovskite quantum dots (QDs), as one kind of promising materials, have attracted considerable attention in optoelectronic applications. Herein, we synthesized the colloidal CsPbBr3 QDs with tunable photoluminescence (PL) (493-531 nm) by adjusting the reaction temperatures, which revealed narrow emission bandwidths of about 25 nm. The average diameters of the QDs could be adjusted from 7.1 to 12.3 nm as the temperature increased from 100 °C to 180 °C. Moreover, the radiative lifetimes of CsPbBr3 QDs were measured to be 2 ns, and the single QD fluorescence intensity time trace results demonstrated its suppressed blinking emission. Moreover, green light emitting diodes by using CsPbBr3 QDs casted on blue LED chips were further fabricated, which provided potential applications in the field of display and lighting technology.

  5. Photoluminescence properties of ZnTe homoepitaxial films deposited by synchrotron-radiation-excited growth

    International Nuclear Information System (INIS)

    Nishio, Mitsuhiro; Hayashida, Kazuki; Harada, Hiroki; Mitsuishi, Yoshiaki; Guo Qixin; Ogawa, Hiroshi

    2001-01-01

    ZnTe homoepitaxial films have been deposited at substrate temperatures between 27 deg. C and 100 deg. C by synchrotron-radiation-excited growth using diethylzinc and diethyltelluride. Effects of diethylzinc transport rate and substrate temperature upon the photoluminescence properties of the ZnTe films have been clarified. Strong deep level emissions centered at 1.85 and 2.1 eV related to defects such as vacancy-impurity complex become emerged with increasing diethylzinc transport rate or substrate temperature. A sharply excitonic emission at 2.375 eV associated with shallow acceptors is observed and neither a donor-acceptor pair recombination nor a deep level luminescence signal is detected in the spectrum of the film grown under the nearly stoichiometric condition, which indicates that ZnTe films of good quality can be grown even at room temperature by this growth technique

  6. Entrance- and exit-channel effects and the suppression of neutron emission from 64Ni+92Zr→/sup 156/Er/sup */

    International Nuclear Information System (INIS)

    Love, D.J.G.; Bishop, P.J.; Kirwan, A.; Nolan, P.J.; Thornley, D.J.; Nelson, A.H.; Twin, P.J.

    1986-01-01

    High--angular-momentum components have been found in the cross section for /sup 64/Ni+/sup 92/Zr→/sup 156/Er /sup */ by γ-ray spectroscopy. They are expected to influence the known low evaporation-neutron multiplicity. The feeding pattern rules out significant trapping in superdeformed states at low spin, an explanation previously advanced. Simple coupled-channels calculations are consistent with the observations. The statistical model with high-l fusion enhanced consistently with observation reproduces the neutron multiplicity satisfactorily

  7. Effect of lead salts on phase, morphologies and photoluminescence of nanocrystalline PbMoO4 and PbWO4 synthesized by microwave radiation

    Directory of Open Access Journals (Sweden)

    Phuruangrat Anukorn

    2016-09-01

    Full Text Available PbMoO4 and PbWO4 were successfully synthesized by microwave radiation using different lead salts (acetate, chloride, nitrate and sulfate and Na2MO4 (M = Mo, W in propylene glycol. The products were characterized by X-ray diffraction (XRD, scanning and transmission electron microscopy (SEM, TEM, Fourier transform infrared (FT-IR, Raman spectroscopy and photoluminescence (PL spectroscopy. In this research, morphologies, crystallization and photoluminescence of the products were influenced by the kinetics of anions, including the detection of M–O (M = Mo, W stretching modes in the (MO42− tetrahedrons. Photoluminescence of PbMoO4 synthesized from Pb(NO32 and of PbWO4 synthesized from PbCl2 showed the strongest blue emission due to the electronic diffusion in tetrahedrons at room temperature.

  8. Effect of heat treatment on the structure of incorporated oxalate species and photoluminescent properties of porous alumina films formed in oxalic acid

    Science.gov (United States)

    Vrublevsky, I.; Jagminas, A.; Hemeltjen, S.; Goedel, W. A.

    2008-09-01

    The present work focuses on the use of IR spectroscopy and photoluminescence spectral measurements for studying the treatment temperature effect on the compositional and luminescent properties of oxalic acid alumina films. In line with the recent researches we have also found that heat treatment of porous alumina films formed in oxalic acid leads to considerable changes in their photoluminescence properties: upon annealing the intensity of photoluminescence (PL) increases reaching a maximum at the temperature of around 500 °C and then decreases. IR spectra of as-grown and heat-treated films have proved that PL emission in the anodic alumina films is related with the state of 'structural' oxalate species incorporated in the oxide lattice. These results allowed us to conclude that PL behavior of oxalic acid alumina films can be explained through the concept of variations in the bonding molecular orbitals of incorporated oxalate species including σ- and π-bonds.

  9. Theoretical and experimental study of disordered Ba0.45Sr0.55 TiO3 photoluminescence at room temperature

    International Nuclear Information System (INIS)

    Souza, I.A.; Gurgel, M.F.C.; Santos, L.P.S.; Goes, M.S.; Cava, S.; Cilense, M.; Rosa, I.L.V.; Paiva-Santos, C.O.; Longo, E.

    2006-01-01

    Disordered and crystalline Ba 0.45 Sr 0.55 TiO 3 (BST) powder processed at low temperature was synthesized by the polymeric precursor method. The single-phase perovskite structure of the ceramics was identified by the Raman and X-ray diffraction techniques. Photoluminescence at room temperature was observed only in a disordered BST sample. Increasing the calcination time intensified the photoluminescence (PL), which reached its maximum value in the sample heat treated at 300 deg. C for 30 h. This emission may be correlated with the structural disorder. Periodic ab initio quantum-mechanical calculations using the CRYSTAL98 program can yield important information regarding the electronic and structural properties of crystalline and disordered solids. The experimental and theoretical results indicate the presence of intermediary energy levels in the band gap. This is ascribed to the break in symmetry, which is responsible for visible photoluminescence in the material's disordered state at room temperature

  10. The role of structural order-disorder for visible intense photoluminescence in the BaZr0.5Ti0.5O3 thin films

    International Nuclear Information System (INIS)

    Anicete-Santos, M.; Cavalcante, L.S.; Orhan, E.; Paris, E.C.; Simoes, L.G.P.; Joya, M.R.; Rosa, I.L.V.; Lucena, P.R. de; Santos, M.R.M.C.; Santos-Junior, L.S.; Pizani, P.S.; Leite, E.R.; Varela, J.A.; Longo, E.

    2005-01-01

    The nature of the intense visible room temperature photoluminescence of BaZr 0.5 Ti 0.5 O 3 non-crystalline thin films is discussed in the light of experimental results and theoretical calculations. The photoluminescence measurements reveal that the emission intensity changes with the degree of disorder in the BaZr 0.5 Ti 0.5 O 3 lattice. First principles quantum mechanical techniques, based on density functional theory at B3LYP level, have been employed to study the electronic structure of a crystalline model and of structurally disordered models in order to detect the influence of disorder on the electronic structure. An analysis of the electronic charge distribution reveals local polarization in the disordered structures. The relevance of the present theoretical and experimental results on the photoluminescence behavior of BZT is discussed

  11. Photoluminescence Enhancement of Silole-Capped Silicon Quantum Dots Based on Förster Resonance Energy Transfer.

    Science.gov (United States)

    Kim, Seongwoong; Kim, Sungsoo; Ko, Young Chun; Sohn, Honglae

    2015-07-01

    Photoluminescent porous silicon were prepared by an electrochemical etch of n-type silicon under the illumination with a 300 W tungsten filament bulb for the duration of etch. The red photoluminescence emitting at 650 nm with an excitation wavelength of 450 nm is due to the quantum confinement of silicon quantum dots in porous silicon. HO-terminated red luminescent PS was obtained by an electrochemical treatment of fresh PS with the current of 150 mA for 60 seconds in water and sodium chloride. As-prepared PS was sonicated, fractured, and centrifuged in toluene solution to obtain photoluminescence silicon quantum dots. Dichlorotetraphenylsilole exhibiting an emission band at 520 nm was reacted with HO-terminated silicon quantum dots to give a silole-capped silicon quantum dots. The optical characterization of silole-derivatized silicon quantum dots was investigated by UV-vis and fluorescence spectrometer. The fluorescence emission efficiency of silole-capped silicon quantum dots was increased by about 2.5 times due to F6rster resonance energy transfer from silole moiety to silicon quantum dots.

  12. Photoexcited emission efficiencies of zinc oxide

    Science.gov (United States)

    Foreman, John Vincent

    Optoelectronic properties of the II-VI semiconductor zinc oxide (ZnO) have been studied scientifically for almost 60 years; however, many fundamental questions remain unanswered about its two primary emission bands--the exciton-related luminescence in the ultraviolet and the defect-related emission band centered in the green portion of the visible spectrum. The work in this dissertation was motivated by the surprising optical properties of a ZnO nanowire sample grown by the group of Prof. Jie Liu, Department of Chemistry, Duke University. We found that this nanowire sample exhibited defect-related green/white emission of unprecedented intensity relative to near-band-edge luminescence. The experimental work comprising this dissertation was designed to explain the optical properties of this ZnO nanowire sample. Understanding the physics underlying such exceptional intensity of green emission addresses many of the open questions of ZnO research and assesses the possibility of using ZnO nanostructures as an ultraviolet-excited, broadband visible phosphor. The goal of this dissertation is to provide insight into what factors influence the radiative and nonradiative recombination efficiencies of ZnO by characterizing simultaneously the optical properties of the near-band-edge ultraviolet and the defect-related green emission bands. Specifically, we seek to understand the mechanisms of ultraviolet and green emission, the mechanism of energy transfer between them, and the evolution of their emission efficiencies with parameters such as excitation density and sample temperature. These fundamental but unanswered questions of ZnO emission are addressed here by using a novel combination of ultrafast spectroscopic techniques in conjunction with a systematic set of ZnO samples. Through this systematic investigation, ZnO may be realistically assessed as a potential green/white light phosphor. Photoluminescence techniques are used to characterize the thermal quenching behavior of

  13. Synthesis and photoluminescence study of rare earth activated phosphor Na2La2B2O7

    International Nuclear Information System (INIS)

    Nagpure, P.A.; Omanwar, S.K.

    2012-01-01

    The photoluminescence properties in UV and N-UV excitable range for the phosphors of Na 2 La 2 B 2 O 7 : RE (RE=Eu, Tb, Ce, Sm, Gd) are investigated. The solution combustion synthesis technique was employed for the synthesis of the phosphors Na 2 La 2 B 2 O 7 : RE. The photoluminescence measurements of the phosphors were carried out on a HITACHI F7000 Fluorescence Spectrophotometer. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Na 2 La 2 B 2 O 7 : Eu are 591 and 615 nm, Na 2 La 2 B 2 O 7 : Ce shows dominating emission peak at 387 nm and Na 2 La 2 B 2 O 7 : Tb displays green emission at 493, 544, 593 and 620 nm at 254 nm excitation, while Na 2 La 2 B 2 O 7 : Sm shows the main emission peak wavelengths 566 and 604 nm at 405 nm excitation and Na 2 La 2 B 2 O 7 : Gd shows dominating emission peak at 312 nm at 274 nm excitation. These phosphors may provide a new kind of luminescent materials under ultraviolet and near ultraviolet excitation for various applications. - Highlights: ► We use the combustion technique for synthesis of Na 2 La 2 B 2 O 7 : RE phosphor. ► Phosphor Na 2 La 2 B 2 O 7 : Eu 3+ shows intense red emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Tb 3+ shows intense green emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Sm 3+ shows orange red emission under near UV excitation. ► Phosphors Na 2 La 2 B 2 O 7 : Ce 3+ and Na 2 La 2 B 2 O 7 : Gd 3+ show near UV and UVB emissions under UV excitation.

  14. Novel Electrospun Dual-Layered Composite Nanofibrous Membrane Endowed with Electricity-Magnetism Bifunctionality at One Layer and Photoluminescence at the Other Layer.

    Science.gov (United States)

    Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2016-10-05

    Dual-layered composite nanofibrous membrane equipped with electrical conduction, magnetism and photoluminescence trifunctionality is constructed via electrospinning. The composite membrane consists of a polyaniline (PANI)/Fe 3 O 4 nanoparticles (NPs)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional nanofibrous layer at one side and a Eu(TTA) 3 (TPPO) 2 /polyvinylpyrrolidone (PVP) photoluminescent nanofibrous layer at the other side, and the two layers are tightly combined face-to-face together into the novel dual-layered composite membrane with trifunctionality. The electric conductivity and magnetism of electrical-magnetic bifunctionality can be respectively tunable via modulating the respective PANI and Fe 3 O 4 NPs contents, and the highest electric conductivity approaches the order of 1 × 10 -2 S cm -1 . Predominant red emission at 615 nm can be obviously observed in the photoluminescent layer under 366 nm excitation. Moreover, the luminescent intensity of photoluminescent layer is almost unaffected by the electrical-magnetic bifunctional layer because of the fact that the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe 3 O 4 NPs. The novel dual-layered composite nanofibrous membrane with trifunctionality has potentials in many fields. Furthermore, the design philosophy and fabrication method for the dual-layered multifunctional membrane provide a new and facile strategy toward other membranes with multifunctionality.

  15. Changes of photoluminescence of electron beam irradiated self-assembled InAs/GaAs quantum dots

    Science.gov (United States)

    Maliya; Aierken, Abuduwayiti; Li, Yudong; Zhou, Dong; Zhao, Xiaofan; Guo, Qi; Liu, Chaoming

    2018-03-01

    We investigate the effects of 1.0MeV electron beam irradiation on the photoluminescence of self-assembled InAs/GaAs quantum dots. After irradiation doses up to 1×1016e-/cm2 , photoluminescence of all samples was degraded dramatically and some additional radiation-induced changes in photo-carrier recombination from QDs, which include a slight increase in PL emission with low electron doses under different photo-injection condition in two samples, are also noticed. Different energy shift was observed in two samples with different Quantum Dot sizes. We attribute this remarkable phenomenon to combination of stress relaxation induced red-shift and In-Ga intermixing caused blue-shift.

  16. Structural, optical, and photoluminescence characterization of electron beam evaporated ZnS/CdSe nanoparticles thin films

    Science.gov (United States)

    Mohamed, S. H.; Ali, H. M.

    2011-01-01

    Structural, optical, and photoluminescence investigations of ZnS capped with CdSe films prepared by electron beam evaporation are presented. X-ray diffraction analysis revealed that the ZnS/CdSe nanoparticles films contain cubic cadmium selenide and hexagonal zinc sulfide crystals and the ZnS grain sizes increased with increasing ZnS thickness. The refractive index was evaluated in terms of envelope method, which has been suggested by Swanepoel in the transparent region. The refractive index values were found to increase with increasing ZnS thickness. However, the optical band gap and the extinction coefficient were decreased with increasing ZnS thickness. Photoluminescence (PL) investigations revealed the presence of two broad emission bands. The ZnS thickness significantly influenced the PL intensities.

  17. Atomic retention and near infrared photoluminescence from PbSe nanocrystals fabricated by sequential ion implantation and electron beam annealing

    International Nuclear Information System (INIS)

    Carder, D.A.; Markwitz, A.; Reeves, R.J.; Kennedy, J.; Fang, F.

    2013-01-01

    Nanocrystals of PbSe have been fabricated in a silicon dioxide matrix by sequential low energy ion implantation followed by an electron beam annealing step. Transmission electron microscopy reveals PbSe nanocrystals with typical sizes between 3 and 10 nm in the sub-surface region. Rutherford Backscattering Spectrometry has been used to study the total atomic retention, as a function of implanted atoms, following annealing. Photoluminescence was observed in various samples, at 4 K, as a broad peak between 1.4 and 2.0 μm, with observation of a dependence of the peak wavelength on annealing temperature. Room temperature photoluminescence was observed for samples with a high retention of implanted atoms, demonstrating the importance of nanocrystal density for achieving ambient temperature emission in these systems

  18. Tuning effect of polysaccharide Chitosan on structural, morphological, optical and photoluminescence properties of ZnO nanoparticles

    Science.gov (United States)

    Magesh, G.; Bhoopathi, G.; Nithya, N.; Arun, A. P.; Ranjith Kumar, E.

    2018-05-01

    Chitosan/ZnO nanocomposites was synthesized by in-situ chemical precipitation method. The effect of polysaccharide Chitosan concentration (0.1 g, 0.5 g, 1 g and 3 g) was investigated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) with Energy dispersive spectroscopy (EDX), High Resolution Transmission Electron Microscopy (HRTEM), UV-visible (UV), Fourier Transform Infrared (FTIR) and Photoluminescence Spectroscopy (PL). XRD pattern confirms the hexagonal wurtzite structure of the Chitosan/ZnO nanocomposites. The structural morphology and the elemental composition of the samples were analysed by FESEM and EDX respectively. From TEM analysis, it is observed that the particles in spindle shape morphology with average particle size ranges 10-20 nm. UV-Vis analysis reveals that the Chitosan concentration affect the absorption band edge and shift towards lower wavelength. The oxygen vacancy induced photoluminescence of ZnO nanoparticles was observed and its intensity decreases by tuning the Chitosan concentration.

  19. Kinetic description of self-field effects on laser and betatron emission in wiggler-pumped ion-channel free electron lasers

    International Nuclear Information System (INIS)

    Alimohamadi, M; Mehdian, H; Hasanbeigi, A

    2011-01-01

    The effects of self-fields on the free electron lasers (FELs) with a helical wiggler and ion-channel guiding are considered. The steady-state orbits for a single electron in this configuration are obtained. The rate of change of axial velocity with energy, the characteristic function Φ, is derived and studied numerically. A kinetic approach has been used to get the effects of self-field on the FEL and betatron gain formula in the low-gain-pre-pass limit. It is shown that betatron gain is smaller than FEL gain. We also found a gain decrement (enhancement), arising from diamagnetism (paramagnetism) generated by the self-magnetic field for group I (group II) orbits. It is interesting that the gain enhancement is found for the non-relativistic part of group II orbits. The FEL gain and betatron gain have also been investigated for different relativistic factors γ.

  20. Studies on Characterization, Optical Absorption, and Photoluminescence of Yttrium Doped ZnS Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ranganaik Viswanath

    2014-01-01

    Full Text Available Pure ZnS and ZnS:Y nanoparticles were synthesized by a chemical coprecipitation route using EDTA-ethylenediamine as a stabilizing agent. X-ray diffraction (XRD, high resolution transmission electron microscopy (HRTEM, field emission scanning electron microscopy (FE-SEM, Fourier transform infrared spectrometry (FTIR, thermogravimetric-differential scanning calorimetry (TG-DSC, and UV-visible and photoluminescence (PL spectroscopy were employed to characterize the as-synthesized ZnS and ZnS:Y nanoparticles, respectively. XRD and TEM studies show the formation of cubic ZnS:Y particles with an average size of ~4.5 nm. The doping did not alter the phase of the zinc sulphide, as a result the sample showed cubic zincblende structure. The UV-visible spectra of ZnS and ZnS:Y nanoparticles showed a band gap energy value, 3.85 eV and 3.73 eV, which corresponds to a semiconductor material. A luminescence characteristics such as strong and stable visible-light emissions in the orange region alone with the blue emission peaks were observed for doped ZnS nanoparticles at room temperature. The PL intensity of orange emission peak was found to be increased with an increase in yttrium ions concentration by suppressing blue emission peaks. These results strongly propose that yttrium doped zinc sulphide nanoparticles form a new class of luminescent material.

  1. THE DETERMINATION THE POLLUTION EMISSIONS OF SO2, NOX, CO, CO2 AND O2 FROM THE CHANNELS OF BURNT GAS ON BOILER OF 420 T/H - STEAM, IN THE SIGHT APPLICATION PROCEEDING TO REDUCE OF THESE

    Directory of Open Access Journals (Sweden)

    Valentin Nedeff

    2007-03-01

    Full Text Available The work present the results obtained after dynamic analyze the pollution emissions of SO2, NOx, CO, CO2 and O2 on evacuation channels of burnt gas on boiler of 420 t/h steam, having right the basic combustible the lignite, and auxiliary combustible the fuel oil and the natural gas. The values of pollution emission was analyze beside the admissible maxims values required by European legislation for Romania in the year 2005. The conclusion elaborated it adverted to: the values of oxides azoth, carry they frame in the limits provide in Environmental Authorization, under 60 mg/Nmc on 6% oxygen, the concentration values of SO2 which was bigger in report with one authorized comprised between 3500-3900 mg/Nmc confronted by 3400 mg/Nm. For integration in the foresee Government Decision 541/2003 aren't sufficient just proceeding of below reduce SO2, must take and another measures such as: get the fuel with quantity of sulphur 0.5% and with a content of ash below 35%.

  2. Structural, morphological, optical and photoluminescence properties of HfO2 thin films

    International Nuclear Information System (INIS)

    Ma, C.Y.; Wang, W.J.; Wang, J.; Miao, C.Y.; Li, S.L.; Zhang, Q.Y.

    2013-01-01

    Nanocrystalline monoclinic HfO 2 films with an average crystal size of 4.2–14.8 nm were sputter deposited under controlled temperatures and their structural characteristics and optical and photoluminescence properties have been evaluated. Structural investigations indicate that monoclinic HfO 2 films grown at higher temperatures above 400 °C are highly oriented along the (− 111) direction. The lattice expansion increases with diminishing HfO 2 crystalline size below 6.8 nm while maximum lattice expansion occurs with highly oriented monoclinic HfO 2 of crystalline size about 14.8 nm. The analysis of atomic force microscopy shows that the film growth at 600 °C can be attributed to the surface-diffusion-dominated growth. The intensity of the shoulderlike band that initiates at ∼ 5.7 eV and saturates at 5.94 eV shows continued increase with increasing crystalline size, which is intrinsic to nanocrystalline monoclinic HfO 2 films. Optical band gap varies in the range 5.40 ± 0.03–5.60 ± 0.03 eV and is slightly decreased with the increase in crystalline size. The luminescence band at 4.0 eV of HfO 2 films grown at room temperature can be ascribed to the vibronic transition of excited OH · radical while the emission at 3.2–3.3 eV for the films grown at all temperatures was attributed to the radiative recombination at impurity and/or defect centers. - Highlights: • Nanocrystalline monoclinic HfO 2 films were sputter deposited. • Structural, optical and photoluminescence properties were studied. • To analyze the scaling behavior using the power spectral density • Optical and photoluminescence properties strongly depend on film growth temperature

  3. Photoluminescent properties of complex metal oxide nanopowders for gas sensing

    Science.gov (United States)

    Bovhyra, R. V.; Mudry, S. I.; Popovych, D. I.; Savka, S. S.; Serednytski, A. S.; Venhryn, Yu. I.

    2018-03-01

    This work carried out research on the features of photoluminescence of the mixed and complex metal oxide nanopowders (ZnO/TiO2, ZnO/SnO2, Zn2SiO4) in vacuum and gaseous ambient. The nanopowders were obtained using pulsed laser reactive technology. The synthesized nanoparticles were characterized by X-ray diffractometry, energy-dispersive X-ray analysis, and scanning and transmission electron microscopy analysis for their sizes, shapes and collocation. The influence of gas environment on the photoluminescence intensity was investigated. A change of ambient gas composition leads to a rather significant change in the intensity of the photoluminescence spectrum and its deformation. The most significant changes in the photoluminescent spectrum were observed for mixed ZnO/TiO2 nanopowders. This obviously is the result of a redistribution of existing centers of luminescence and the appearance of new adsorption centers of luminescence on the surface of nanopowders. The investigated nanopowders can be effectively used as sensing materials for the construction of the multi-component photoluminescent sensing matrix.

  4. Effect of gamma irradiation on the photoluminescence of porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Elistratova, M. A., E-mail: Marina.Elistratova@mail.ioffe.ru; Romanov, N. M. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Goryachev, D. N. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Zakharova, I. B. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Sreseli, O. M. [Russian Academy of Sciences, Ioffe Institute (Russian Federation)

    2017-04-15

    The effect of gamma irradiation on the luminescence properties of porous silicon produced by the electrochemical technique is studied. Changes in the photoluminescence intensity between irradiation doses and over a period of several days after the last irradiation are recorded. The quenching of photoluminescence at low irradiation doses and recovery after further irradiation are registered. It is found that porous silicon is strongly oxidized after gamma irradiation and the oxidation process continues for several days after irradiation. It is conceived that the change in the photoluminescence spectra and intensity of porous silicon after gamma irradiation is caused by a change in the passivation type of the porous surface: instead of hydrogen passivation, more stable oxygen passivation is observed. To stabilize the photoluminescence spectra of porous silicon, the use of fullerenes is proposed. No considerable changes in the photoluminescence spectra during irradiation and up to 18 days after irradiation are detected in a porous silicon sample with a thermally deposited fullerene layer. It is shown that porous silicon samples with a deposited C{sub 60} layer are stable to gamma irradiation and oxidation.

  5. Channel box

    International Nuclear Information System (INIS)

    Tanabe, Akira.

    1993-01-01

    In a channel box of a BWR type reactor, protruding pads are disposed in axial position on the lateral side of a channel box opposing to a control rod and facing the outer side portion of the control rod in a reactor core loaded state. In the initial loading stage of fuel assemblies, channel fasteners and spacer pads are abutted against each other in the upper portion between the channel boxes sandwiching the control rod therebetween. Further, in the lower portion, a gap as a channel for the movement of the control rod is ensured by the support of fuel support metals. If the channel box is bent toward the control rod along with reactor operation, the pads are abutted against each other to always ensure the gap through which the control rod can move easily. Further, when the pads are brought into contact with each other, the bending deformation of the channel box is corrected by urging to each other. Thus, the control rod can always be moved smoothly to attain reactor safety operation. (N.H.)

  6. Fast neutron radiography using photoluminescent imaging plates

    International Nuclear Information System (INIS)

    Rant, J.; Kristof, E.; Balasko, M.; Stade, J.

    1999-01-01

    Fast neutron radiography (FNR) and resonance neutron radiography (RNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation used for the inspection of thick metal objects. In both non-destructive methods, the contrast sensitivity and the penetration power can be improved by using higher energy neutrons. At present direct techniques based either n Solid State Nuclear Track detectors (SSNTDs) or scintillating screens and transfer techniques using activation threshold detectors and radiographic films are applied for the detection of fast neutron images. Rather low detection sensitivity of film and SSNTD based fast neutron imaging methods and also rather poor inherent image contrast of SSNTD pose a problem for FNR in the fast neutron energy region 1-15 MeV interesting for NDT. For more efficient detection of fast neutron images the use of novel highly sensitive photoluminescent imaging plates (IP) in combination with threshold at the KFKI research reactor. The conventional IP produced by FUJI Photo Film Co. for the detection of beta and X-ray radiation were used. The threshold activation detectors were the reactions 115 In(n, n') 115m In, 64 Zn(n,p) 64 Cu, 56 Fe(n, p) 56 Mn, 24 Mg(n, p) 24 Na and 27 Al(n, α) 24 Na. These threshold reactions cover the fast neutron energy region between 0,7 MeV and 12 MeV. Pure, commercially available metals 0,1 mm to 0,25 mm thick made of In, Zn, Fe, Mg and Al were used as converter screens. The very high sensitivity of IP, the linearity of their response over 5 decades of exposure dose and the high dynamic digitalisation latitude enabled fast neutron radiography of image quality comparable to the quality of thermal NR. In our experimental conditions (φ n ∼ 10 8 n/cm 2 s, R Cd ∼ 2) the neutron exposure and IP exposure periods were still practical and comparable to the half life of the corresponding reaction products (half an hour to several hours). Even with the 27 Al(n.α) 24

  7. Growth and photoluminescence of vertically aligned ZnO nanowires/nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Fang Fang; Zhao Dongxu; Li Binghui; Zhang Zhenzhong; Zhang Jiying; Shen Dezhen, E-mail: dxzhao2000@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun 130033 (China)

    2009-07-07

    By controlling the incoming gas flow, vertically aligned ZnO nanowires and nanowalls have been successfully synthesized on a Si (1 0 0) substrate by the simple physical vapour deposition method. The growth process of the ZnO nanowalls was observed by adjusting the growth time. The probable growth mechanisms of the ZnO nanowires and nanowalls were discussed in detail. In contrast to the photoluminescence results of nanowires, an enhancement of the LO phonon signal was observed in ZnO nanowalls, which was attributed to an additional channel of electron-phonon coupling induced by the residual strains in the ZnO nanowalls during the coalescence growth process.

  8. Photoluminescence and positron annihilation spectroscopic investigation on a H+ irradiated ZnO single crystal

    Science.gov (United States)

    Sarkar, A.; Chakrabarti, Mahuya; Sanyal, D.; Bhowmick, D.; Dechoudhury, S.; Chakrabarti, A.; Rakshit, Tamita; Ray, S. K.

    2012-08-01

    Low temperature photoluminescence and room temperature positron annihilation spectroscopy have been employed to investigate the defects incorporated by 6 MeV H+ ions in a hydrothermally grown ZnO single crystal. Prior to irradiation, the emission from donor bound excitons is at 3.378 eV (10 K). The irradiation creates an intense and narrow emission at 3.368 eV (10 K). The intensity of this peak is nearly four times that of the dominant near band edge peak of the pristine crystal. The characteristic features of the 3.368 eV emission indicate its origin as a ‘hydrogen at oxygen vacancy’ type defect. The positron annihilation lifetime measurement reveals a single component lifetime spectrum for both the unirradiated (164 ± 1 ps) and irradiated crystal (175 ± 1 ps). It reflects the fact that the positron lifetime and intensity of the new irradiation driven defect species are a little higher compared to those in the unirradiated crystal. However, the estimated defect concentration, even considering the high dynamic defect annihilation rate in ZnO, comes out to be ˜4 × 1017 cm-3 (using SRIM software). This is a very high defect concentration compared to the defect sensitivity of positron annihilation spectroscopy. A probable reason is the partial filling of the incorporated vacancies (positron traps), which in ZnO are zinc vacancies. The positron lifetime of ˜175 ps (in irradiated ZnO) is consistent with recent theoretical calculations for partially hydrogen-filled zinc vacancies in ZnO. Passivation of oxygen vacancies by hydrogen is also reflected in the photoluminescence results. A possible reason for such vacancy filling (at both Zn and O sites) due to irradiation has also been discussed.

  9. Photoluminescence and positron annihilation spectroscopic investigation on a H+ irradiated ZnO single crystal

    International Nuclear Information System (INIS)

    Sarkar, A; Chakrabarti, Mahuya; Sanyal, D; Bhowmick, D; Dechoudhury, S; Chakrabarti, A; Rakshit, Tamita; Ray, S K

    2012-01-01

    Low temperature photoluminescence and room temperature positron annihilation spectroscopy have been employed to investigate the defects incorporated by 6 MeV H + ions in a hydrothermally grown ZnO single crystal. Prior to irradiation, the emission from donor bound excitons is at 3.378 eV (10 K). The irradiation creates an intense and narrow emission at 3.368 eV (10 K). The intensity of this peak is nearly four times that of the dominant near band edge peak of the pristine crystal. The characteristic features of the 3.368 eV emission indicate its origin as a ‘hydrogen at oxygen vacancy’ type defect. The positron annihilation lifetime measurement reveals a single component lifetime spectrum for both the unirradiated (164 ± 1 ps) and irradiated crystal (175 ± 1 ps). It reflects the fact that the positron lifetime and intensity of the new irradiation driven defect species are a little higher compared to those in the unirradiated crystal. However, the estimated defect concentration, even considering the high dynamic defect annihilation rate in ZnO, comes out to be ∼4 × 10 17 cm -3 (using SRIM software). This is a very high defect concentration compared to the defect sensitivity of positron annihilation spectroscopy. A probable reason is the partial filling of the incorporated vacancies (positron traps), which in ZnO are zinc vacancies. The positron lifetime of ∼175 ps (in irradiated ZnO) is consistent with recent theoretical calculations for partially hydrogen-filled zinc vacancies in ZnO. Passivation of oxygen vacancies by hydrogen is also reflected in the photoluminescence results. A possible reason for such vacancy filling (at both Zn and O sites) due to irradiation has also been discussed. (paper)

  10. Photoluminescence and positron annihilation spectroscopic investigation on a H(+) irradiated ZnO single crystal.

    Science.gov (United States)

    Sarkar, A; Chakrabarti, Mahuya; Sanyal, D; Bhowmick, D; Dechoudhury, S; Chakrabarti, A; Rakshit, Tamita; Ray, S K

    2012-08-15

    Low temperature photoluminescence and room temperature positron annihilation spectroscopy have been employed to investigate the defects incorporated by 6 MeV H(+) ions in a hydrothermally grown ZnO single crystal. Prior to irradiation, the emission from donor bound excitons is at 3.378 eV (10 K). The irradiation creates an intense and narrow emission at 3.368 eV (10 K). The intensity of this peak is nearly four times that of the dominant near band edge peak of the pristine crystal. The characteristic features of the 3.368 eV emission indicate its origin as a 'hydrogen at oxygen vacancy' type defect. The positron annihilation lifetime measurement reveals a single component lifetime spectrum for both the unirradiated (164 ± 1 ps) and irradiated crystal (175 ± 1 ps). It reflects the fact that the positron lifetime and intensity of the new irradiation driven defect species are a little higher compared to those in the unirradiated crystal. However, the estimated defect concentration, even considering the high dynamic defect annihilation rate in ZnO, comes out to be ∼4 × 10(17) cm(-3) (using SRIM software). This is a very high defect concentration compared to the defect sensitivity of positron annihilation spectroscopy. A probable reason is the partial filling of the incorporated vacancies (positron traps), which in ZnO are zinc vacancies. The positron lifetime of ∼175 ps (in irradiated ZnO) is consistent with recent theoretical calculations for partially hydrogen-filled zinc vacancies in ZnO. Passivation of oxygen vacancies by hydrogen is also reflected in the photoluminescence results. A possible reason for such vacancy filling (at both Zn and O sites) due to irradiation has also been discussed.

  11. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  12. Vacuum ultraviolet excited photoluminescence properties of Gd2O2CO3:Eu3+ phosphor

    Institute of Scientific and Technical Information of China (English)

    WANG Zhilong; WANG Yuhua; ZHANG Jiachi

    2008-01-01

    The Gd2O2CO3:Eu3+ with type-II structure phosphor was successfully synthesized via flux method at 400℃ and their photoluminescence properties in vacuum ultraviolet (VUV) region were examined. The broad and strong excitation bands in the range of 153-205 nm owing to the CO32- host absorption and charge transfer (CT) of Gd3+-O2- were observed for Gd2O2CO3:Eu3+. Under 172 nm excitation, Gd2O2CO3:Eu3+ exhibited strong red emission with good color purity, indicating Eu3+ ions located at low symmetry sites and the chromaticity coordination of luminescence for Gd2O2CO3:Eu3+ was (x=0.652, y=0.345). The photoluminescence quenching concentration of Eu3+ excited by 172 nm for Gd2O2CO3:Eu3+ was about 5%. Gd2O2CO3:Eu3+ would be a potential VUV-excited red phosphor applied in mercury-free fluorescent lamps.

  13. Photoluminescence and thermoluminescence properties of BaGa2O4

    Science.gov (United States)

    Noto, L. L.; Poelman, D.; Orante-Barrón, V. R.; Swart, H. C.; Mathevula, L. E.; Nyenge, R.; Chithambo, M.; Mothudi, B. M.; Dhlamini, M. S.

    2018-04-01

    Rare-Earth free luminescent materials are fast becoming important as the cost of rare earth ions gradually increases. In this work, a Rare-Earth free BaGa2O4 luminescent compound was prepared by solid state chemical reaction, which was confirmed to have a single phase by X-ray Diffraction. The Backscattered Electron image and Energy Dispersive X-ray spectroscopy maps confirmed irregular particle and homogeneous compound formation, respectively. The Photoluminescence spectrum displayed broad emission between 350 to 650 nm, which was deconvoluted into two components. The photoluminescence excitation peak was positioned at 254 nm, which corresponds with the band-to-band position observed from the diffuse reflectance spectrum. The band gap was extrapolated to 4.65 ± 0.02 eV using the Kubelka-Munk model. The preliminary thermoluminescence results indicated that the kinetics involved were neither of first nor second order. Additionally, the activation energy of the electrons within the trap centres was approximated to 0.61 ± 0.01 eV using the Initial Rise model.

  14. Mn-doped ZnO nanocrystals synthesized by sonochemical method: Structural, photoluminescence, and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A.A., E-mail: aaelho@yahoo.com [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Osman, M.A. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Ibrahim, E.M.M. [Sohag University, Faculty of Science, Department of Physics, Sohag 82524 (Egypt); Ali, Manar A.; Abd-Elrahim, A.G. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt)

    2017-05-15

    Highlights: • Mn-doped ZnO nanostructures were synthesized by the sonochemical method. • Structural, morphological, optical, photoluminescence and magnetic properties were investigated. • Mn-doped ZnO nanostructures reveal a blue shift of the optical band gap. • Photoluminescence spectra of Mn-doped ZnO nanostructures show quenching in the emission intensity. • Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature. - Abstract: This work reports the synthesis of Mn-doped ZnO nanostructures using ice-bath assisted sonochemical technique. The impact of Mn-doping on structural, morphological, optical, and magnetic properties of ZnO nanostructures is studied. The morphological study shows that the lower doped samples possess mixtures of nanosheets and nanorods while the increase in Mn content leads to improvement of an anisotropic growth in a preferable orientation to form well-defined edge rods at Mn content of 0.04. UV–vis absorption spectra show that the exciton peak in the UV region is blue shifted due to Mn incorporation into the ZnO lattice. Doping ZnO with Mn ions leads to a reduction in the PL intensity due to a creation of more non-radiative recombination centers. The magnetic measurements show that the Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature, as well as variation of the Mn content can significantly affect the ferromagnetic behavior of the samples.

  15. ZnO twin-cones: synthesis, photoluminescence, and catalytic decomposition of ammonium perchlorate.

    Science.gov (United States)

    Sun, Xuefei; Qiu, Xiaoqing; Li, Liping; Li, Guangshe

    2008-05-19

    ZnO twin-cones, a new member to the ZnO family, were prepared directly by a solvothermal method using a mixed solution of zinc nitrate and ethanol. The reaction and growth mechanisms of ZnO twin-cones were investigated by X-ray diffraction, UV-visible spectra, infrared and ion trap mass spectra, and transmission electron microscopy. All as-prepared ZnO cones consisted of tiny single crystals with lengths of several micrometers. With prolonging of the reaction time from 1.5 h to 7 days, the twin-cone shape did not change at all, while the lattice parameters increased slightly and the emission peak of photoluminescence shifted from the green region to the near orange region. ZnO twin-cones are also explored as an additive to promote the thermal decomposition of ammonium perchlorate. The variations of photoluminescence spectra and catalytic roles in ammonium perchlorate decomposition were discussed in terms of the defect structure of ZnO twin-cones.

  16. Low-temperature photoluminescence of CuSe2 nano-objects in selenium thin films

    Directory of Open Access Journals (Sweden)

    Martina Gilić

    2017-06-01

    Full Text Available Thin films of CuSe2 nanoparticles embedded in selenium matrix were prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by photoluminescence spectroscopy (T=20-300K and UV-VIS spectroscopy (T = 300K. Surface morphology was investigated by scanning electron microscopy. The band gap for direct transition in CuSe2 was found to be in the range of 2.72-2.75 eV and that for indirect transition is in the range of 1.71-1.75 eV determined by UV-VIS spectroscopy. On the other hand, selenium exhibits direct band gap in the range of 2.33-2.36 eV. All estimated band gaps slightly decrease with the increase of the film thickness. Photoluminescence spectra of the thin films clearly show emission bands at about 1.63 and 2.32 eV at room temperature, with no shift observed with decreasing temperature. A model was proposed for explaining such anomaly.

  17. Structural refinement, photoluminescence and Raman spectroscopy of wurtzite Mn-doped Zn O pellets

    Energy Technology Data Exchange (ETDEWEB)

    Marquina, J.; Martin, J.; Luengo, J.; Vera, F.; Roa, L. [Centro de Estudios Avanzados en Optica, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Gonzalez, J. [Centro de Estudios de Semiconductores, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Rodriguez, F.; Renero L, C.; Valiente, R. [Malta-Consolider Team, CITIMAC, Facultad de Ciencias, Universidad de Cantabria, Santander 69005 (Spain); Delgado, G. E., E-mail: marquinajesus@gmail.com [Laboratorio de Cristalografia, Facultad de Ciencias, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of)

    2017-11-01

    We report the results of the Rietveld refinement, photoluminescence and Raman spectroscopy of Mn-doped Zn O ceramic pellets. Rietveld refinement shows that samples crystallize in the wurtzite structure and for the Mn-doped sample indicated that the Mn atoms substitute the Zn tetrahedral crystallographic sites in the Zn O host lattice. The emission and absorption spectra of Mn-doped Zn O have been investigated in the visible-UV region and the data have been interpreted in terms of the wurtzite Zn O electronic structure. Two broad bands, one due to superposition between donor bound excitons (DX) and free excitons (FX) and other due free-to bond excitonic recombination (FB) dominates the low-temperature photoluminescence spectra of Mn-doped Zn O bulk. In the Raman spectrum, an extra mode at ∼520 cm{sup -1} has been observed in agreement with earlier works, and it is an indicator for the incorporation of Mn{sup +2} ions into the Zn O host matrix since it is not is observed in Zn O pristine. Rietveld refinement of the X-ray diffraction patterns, energy-dispersive X-ray spectroscopy (EDS) technique, and Raman spectroscopies were performed to study these effects. (Author)

  18. Photoluminescence and doping mechanism of theranostic Eu3+/Fe3+ dual-doped hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Chen, Min-Hua; Lin, Feng-Huei; Yoshioka, Tomohiko; Ikoma, Toshiyuki; Tanaka, Junzo; Hanagata, Nobutaka

    2014-01-01

    Theranostic nanoparticles currently have been regarded as an emerging concept of ‘personalized medicine’ with diagnostic and therapeutic dual-functions. Eu 3+ doped hydroxyapatite (HAp) has been regarded as a promising fluorescent probe for in vivo imaging applications. Additionally, substitution of Ca 2+ with Fe 3+ in HAp crystal may endow the capability of producing heat upon exposure to a magnetic field. Here we report a preliminary study of doping mechanism and photoluminescence of Eu 3+ and Fe 3+ doped HAp nanoparticles (Eu/Fe:HAp). HAp with varied concentration of Eu 3+ and Fe 3+ doping are presented as Eu(10 mol%):HAp, Eu(7 mol%)-Fe(3 mol%):HAp, Eu(5 mol%)-Fe(5 mol%):HAp, Eu(3 mol%)-Fe(7 mol%):HAp, and Fe(10 mol%):HAp in the study. The results showed that the HAp particles, in nano-size with rod-like morphology, were successfully doped with Eu 3+ and Fe 3+ , and the particles can be well suspended in cell culture medium. Photoluminescence analysis revealed that particles have prominent emissions at 536 nm, 590 nm, 615 nm, 650 nm and 695 nm upon excitation at a wavelength of 397 nm. Moreover, these Eu/Fe:HAp nanoparticles belonged to B-type carbonated HAp, which has been considered an effective biodegradable and biocompatible drug/gene carrier in biological applications. (paper)

  19. Photoluminescence and doping mechanism of theranostic Eu3+/Fe3+ dual-doped hydroxyapatite nanoparticles.

    Science.gov (United States)

    Chen, Min-Hua; Yoshioka, Tomohiko; Ikoma, Toshiyuki; Hanagata, Nobutaka; Lin, Feng-Huei; Tanaka, Junzo

    2014-10-01

    Theranostic nanoparticles currently have been regarded as an emerging concept of 'personalized medicine' with diagnostic and therapeutic dual-functions. Eu 3+ doped hydroxyapatite (HAp) has been regarded as a promising fluorescent probe for in vivo imaging applications. Additionally, substitution of Ca 2+ with Fe 3+ in HAp crystal may endow the capability of producing heat upon exposure to a magnetic field. Here we report a preliminary study of doping mechanism and photoluminescence of Eu 3+ and Fe 3+ doped HAp nanoparticles (Eu/Fe:HAp). HAp with varied concentration of Eu 3+ and Fe 3+ doping are presented as Eu(10 mol%):HAp, Eu(7 mol%)-Fe(3 mol%):HAp, Eu(5 mol%)-Fe(5 mol%):HAp, Eu(3 mol%)-Fe(7 mol%):HAp, and Fe(10 mol%):HAp in the study. The results showed that the HAp particles, in nano-size with rod-like morphology, were successfully doped with Eu 3+ and Fe 3+ , and the particles can be well suspended in cell culture medium. Photoluminescence analysis revealed that particles have prominent emissions at 536 nm, 590 nm, 615 nm, 650 nm and 695 nm upon excitation at a wavelength of 397 nm. Moreover, these Eu/Fe:HAp nanoparticles belonged to B-type carbonated HAp, which has been considered an effective biodegradable and biocompatible drug/gene carrier in biological applications.

  20. Photoluminescence spectrum changes of GaN quantum wells caused by the strong piezoelectric fields

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, H.; Calderon, A. [CICATA-IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Gonzalez de la Cruz, G. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico)

    2006-07-01

    Spontaneous and piezoelectric fields are known to be the key to understanding the optical properties of nitride heterostructures. This effect modifies the electronic states in the quantum well (QW) and the emission energy in the photoluminescence (PL) spectrum. These fields induce a reduction of the oscillator strength on the transition energy between the confined electron and hole states in GaN/Al{sub x}Ga{sub 1-x}N QW's and dramatically increase the carrier life time as the QW thickness increases. In this work, we solve analytically the Schroedinger equation for moderate electric fields when the electron-hole transition energy in the QW is larger than the energy gap of the GaN. Furthermore, the large redshifts of the PL energy position and the spatial separation of the electron and hole by several times of the Bohr radius caused by the strong piezoelectric fields are explained using a triangular potential in the Schrodinger equation. The transition energy calculations between the electron-hole pair as a function of the well width with the electric field as a fitting parameter are in agreement with the measured photoluminescence energy peaks. (Author)

  1. Photoluminescence spectrum changes of GaN quantum wells caused by the strong piezoelectric fields

    International Nuclear Information System (INIS)

    Herrera, H.; Calderon, A.; Gonzalez de la Cruz, G.

    2006-01-01

    Spontaneous and piezoelectric fields are known to be the key to understanding the optical properties of nitride heterostructures. This effect modifies the electronic states in the quantum well (QW) and the emission energy in the photoluminescence (PL) spectrum. These fields induce a reduction of the oscillator strength on the transition energy between the confined electron and hole states in GaN/Al x Ga 1-x N QW's and dramatically increase the carrier life time as the QW thickness increases. In this work, we solve analytically the Schroedinger equation for moderate electric fields when the electron-hole transition energy in the QW is larger than the energy gap of the GaN. Furthermore, the large redshifts of the PL energy position and the spatial separation of the electron and hole by several times of the Bohr radius caused by the strong piezoelectric fields are explained using a triangular potential in the Schrodinger equation. The transition energy calculations between the electron-hole pair as a function of the well width with the electric field as a fitting parameter are in agreement with the measured photoluminescence energy peaks. (Author)

  2. Photoluminescence and doping mechanism of theranostic Eu3+/Fe3+ dual-doped hydroxyapatite nanoparticles

    Science.gov (United States)

    Chen, Min-Hua; Yoshioka, Tomohiko; Ikoma, Toshiyuki; Hanagata, Nobutaka; Lin, Feng-Huei; Tanaka, Junzo

    2014-10-01

    Theranostic nanoparticles currently have been regarded as an emerging concept of ‘personalized medicine’ with diagnostic and therapeutic dual-functions. Eu3+ doped hydroxyapatite (HAp) has been regarded as a promising fluorescent probe for in vivo imaging applications. Additionally, substitution of Ca2+ with Fe3+ in HAp crystal may endow the capability of producing heat upon exposure to a magnetic field. Here we report a preliminary study of doping mechanism and photoluminescence of Eu3+ and Fe3+ doped HAp nanoparticles (Eu/Fe:HAp). HAp with varied concentration of Eu3+ and Fe3+ doping are presented as Eu(10 mol%):HAp, Eu(7 mol%)-Fe(3 mol%):HAp, Eu(5 mol%)-Fe(5 mol%):HAp, Eu(3 mol%)-Fe(7 mol%):HAp, and Fe(10 mol%):HAp in the study. The results showed that the HAp particles, in nano-size with rod-like morphology, were successfully doped with Eu3+ and Fe3+, and the particles can be well suspended in cell culture medium. Photoluminescence analysis revealed that particles have prominent emissions at 536 nm, 590 nm, 615 nm, 650 nm and 695 nm upon excitation at a wavelength of 397 nm. Moreover, these Eu/Fe:HAp nanoparticles belonged to B-type carbonated HAp, which has been considered an effective biodegradable and biocompatible drug/gene carrier in biological applications.

  3. Defect-mediated photoluminescence up-conversion in cadmium sulfide nanobelts (Conference Presentation)

    Science.gov (United States)

    Morozov, Yurii; Kuno, Masaru K.

    2017-02-01

    The concept of optical cooling of solids has existed for nearly 90 years ever since Pringsheim proposed a way to cool solids through the annihilation of phonons via phonon-assisted photoluminescence (PL) up-conversion. In this process, energy is removed from the solid by the emission of photons with energies larger than those of incident photons. However, actually realizing optical cooling requires exacting parameters from the condensed phase medium such as near unity external quantum efficiencies as well as existence of a low background absorption. Until recently, laser cooling has only been successfully realized in rare earth doped solids. In semiconductors, optical cooling has very recently been demonstrated in cadmium sulfide (CdS) nanobelts as well as in hybrid lead halide perovskites. For the former, large internal quantum efficiencies, sub-wavelength thicknesses, which decrease light trapping, and low background absorption, all make near unity external quantum yields possible. Net cooling by as much as 40 K has therefore been possible with CdS nanobelts. In this study, we describe a detailed investigation of the nature of efficient anti-Stokes photoluminescence (ASPL) in CdS nanobelts. Temperature-dependent PL up-conversion and optical absorption studies on individual NBs together with frequency-dependent up-converted PL intensity spectroscopies suggest that ASPL in CdS nanobelts is defect-mediated through involvement of defect levels below the band gap.

  4. Influence of preparation and storage conditions on photoluminescence of porous silicon powder with embedded Si nanocrystals

    International Nuclear Information System (INIS)

    Bychto, Leszek; Balaguer, Maria; Pastor, Ester; Chirvony, Vladimir; Matveeva, Eugenia

    2008-01-01

    The time changes of photoluminescence (PL) characteristics of porous silicon (porSi) powder during storing in different ambients have been reported. A porous silicon material with embedded Si nanocrystals of size of few nanometers was prepared by an electrochemical method from 10 to 20 Ωcm p-type Si wafers, and both constant and pulse current anodization regimes were used. A powder with a submicron average particle size was obtained by simple mechanical lift-off of the porous layer followed by additional manual milling. The air, hexane, and water as storage media were used, and modification by a nonionic surfactant (undecylenic acid) of the porSi surface was applied in the latter case. Dependence of PL characteristics on preparation and storage conditions was then studied. A remarkable blue shift of a position of PL maximum was observed in time for porSi powders in each storage media. In water suspension a many-fold build-up (10-30) of PL intensity in a time scale of few days was accompanied by an observed blue shift. Photoluminescence time behavior of porSi powders was described by a known mechanism of the change of porSi PL from free exciton emission of Si nanocrystals to luminescence of localized oxidized states on the Si nanocrystal surface.

  5. Influence of preparation and storage conditions on photoluminescence of porous silicon powder with embedded Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Bychto, Leszek, E-mail: leszek.bychto@tu.koszalin.pl; Balaguer, Maria; Pastor, Ester; Chirvony, Vladimir; Matveeva, Eugenia, E-mail: eumat@upvnet.upv.e [Technical University of Valencia, Nanophotonics Technology Center (Spain)

    2008-12-15

    The time changes of photoluminescence (PL) characteristics of porous silicon (porSi) powder during storing in different ambients have been reported. A porous silicon material with embedded Si nanocrystals of size of few nanometers was prepared by an electrochemical method from 10 to 20 {Omega}cm p-type Si wafers, and both constant and pulse current anodization regimes were used. A powder with a submicron average particle size was obtained by simple mechanical lift-off of the porous layer followed by additional manual milling. The air, hexane, and water as storage media were used, and modification by a nonionic surfactant (undecylenic acid) of the porSi surface was applied in the latter case. Dependence of PL characteristics on preparation and storage conditions was then studied. A remarkable blue shift of a position of PL maximum was observed in time for porSi powders in each storage media. In water suspension a many-fold build-up (10-30) of PL intensity in a time scale of few days was accompanied by an observed blue shift. Photoluminescence time behavior of porSi powders was described by a known mechanism of the change of porSi PL from free exciton emission of Si nanocrystals to luminescence of localized oxidized states on the Si nanocrystal surface.

  6. Influence of preparation and storage conditions on photoluminescence of porous silicon powder with embedded Si nanocrystals

    Science.gov (United States)

    Bychto, Leszek; Balaguer, Maria; Pastor, Ester; Chirvony, Vladimir; Matveeva, Eugenia

    2008-12-01

    The time changes of photoluminescence (PL) characteristics of porous silicon (porSi) powder during storing in different ambients have been reported. A porous silicon material with embedded Si nanocrystals of size of few nanometers was prepared by an electrochemical method from 10 to 20 Ωcm p-type Si wafers, and both constant and pulse current anodization regimes were used. A powder with a submicron average particle size was obtained by simple mechanical lift-off of the porous layer followed by additional manual milling. The air, hexane, and water as storage media were used, and modification by a nonionic surfactant (undecylenic acid) of the porSi surface was applied in the latter case. Dependence of PL characteristics on preparation and storage conditions was then studied. A remarkable blue shift of a position of PL maximum was observed in time for porSi powders in each storage media. In water suspension a many-fold build-up (10-30) of PL intensity in a time scale of few days was accompanied by an observed blue shift. Photoluminescence time behavior of porSi powders was described by a known mechanism of the change of porSi PL from free exciton emission of Si nanocrystals to luminescence of localized oxidized states on the Si nanocrystal surface.

  7. Defect induced tuning of photoluminescence property in graphitic carbon nitride nanosheets through synthesis conditions

    Energy Technology Data Exchange (ETDEWEB)

    Das, D. [School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India); Banerjee, D., E-mail: nilju82@gmail.com [School of Materials Science Engineering Indian Institute of Engineering Science and Technology, Shibpur, Howrah (India); Pahari, D. [School of Materials Science Engineering Indian Institute of Engineering Science and Technology, Shibpur, Howrah (India); Ghorai, U.K. [Department of Industrial Chemistry & Swami Vivekananda Research centre, Ramakrishna Mission Vidyamandira, Belur Math, Howrah 711202 (India); Sarkar, S.; Das, N.S. [School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India); Chattopadhyay, K.K., E-mail: kalyan_chattopadhyay@yahoo.com [School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India); Thin Film and Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India)

    2017-05-15

    Synthesis of layered sheet like graphitic carbon nitride by pyrolysis of urea at different temperatures has been reported. The proper phase formation has been confirmed by X-ray diffraction study whereas field emission scanning and transmission electron microscope characterized the morphology of the material. Fourier transform infrared and Raman spectroscopy revealed the presence of different bonds in the sample. Thermal gravimetric analysis has been used to study the thermal stability of the material. Energy dispersive X-ray analysis further revealed the elemental composition of carbon and nitrogen in a proper stoichiometric ratio. Excitation dependent photoluminescence spectra of the as prepared samples have been studied in detail. It has been shown that synthesis condition can tailor the amount of defects present in the synthesized samples that in turn can change the photoluminescence properties of the material. The fluorescence spectra of the as prepared samples have been used to detect copper ions present in the sample. It has also been shown that the presence of defects which is mainly N-H functional groups can change the decay characteristics of the carrier in these samples which in turn changes the PL spectra.

  8. Photoluminescence properties of white light emitting La2O3:Dy3+ nanocrystals

    Science.gov (United States)

    Reenabati Devi, Konsam; Dorendrajit Singh, Shougaijam; David Singh, Th.

    2018-01-01

    White light emitting nanocrystalline La2O3:Dy3+ phosphors with different concentration (0.5-2 at.%) were synthesized by simple precipitation method. X-ray diffraction (XRD) pattern indicates all the samples crystallizes in the hexagonal phase. Average crystallite sizes of the samples calculated from XRD data were found to be in the range of 20-55 nm. Transmission electron microscopy, selected area electron diffraction, energy dispersive analysis of X-ray and photoluminescence (PL) of the samples are also reported. Strong PL excitation peak due to charge transfer band was observed at 230 nm. Photoluminescence emission peaks observed at 486 and 575 nm were probably attributed to 4F9/2-6H15/2 and 4F9/2-6H13/2 of Dy3+ ions respectively. Optimum luminescence intensity is found at 1 at.% Dy3+ doped La2O3 sample. Further, Commission Internationale de l'é clairage (CIE, 1931) co-ordinates and correlated color temperature (CCT) of the doped sample were calculated to investigate the phosphors' performance and technical applicability of the emitted light respectively. CCT of the 0.5 and 1 at.% samples is 5894 K (white light), within the range of vertical daylight, which makes the synthesised samples promising nanophosphor and may find application in simulating vertical daylight of the Sun.

  9. Spark Channels

    Energy Technology Data Exchange (ETDEWEB)

    Haydon, S. C. [Department of Physics, University of New England, Armidale, NSW (Australia)

    1968-04-15

    A brief summary is given of the principal methods used for initiating spark channels and the various highly time-resolved techniques developed recently for studies with nanosecond resolution. The importance of the percentage overvoltage in determining the early history and subsequent development of the various phases of the growth of the spark channel is discussed. An account is then given of the recent photographic, oscillographic and spectroscopic investigations of spark channels initiated by co-axial cable discharges of spark gaps at low [{approx} 1%] overvoltages. The phenomena observed in the development of the immediate post-breakdown phase, the diffuse glow structure, the growth of the luminous filament and the final formation of the spark channel in hydrogen are described. A brief account is also given of the salient features emerging from corresponding studies of highly overvolted spark gaps in which the spark channel develops from single avalanche conditions. The essential differences between the two types of channel formation are summarized and possible explanations of the general features are indicated. (author)

  10. Terahertz-field-induced photoluminescence of nanostructured gold films

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    We experimentally demonstrate photoluminescence from nanostructured ultrathin gold films subjected to strong single-cycle terahertz transients with peak electric field over 300 kV/cm. We show that UV-Vis-NIR light is being generated and the efficiency of the process is strongly enhanced at the pe......We experimentally demonstrate photoluminescence from nanostructured ultrathin gold films subjected to strong single-cycle terahertz transients with peak electric field over 300 kV/cm. We show that UV-Vis-NIR light is being generated and the efficiency of the process is strongly enhanced...

  11. MgO:Eu3+ red nanophosphor: Low temperature synthesis and photoluminescence properties

    Science.gov (United States)

    Devaraja, P. B.; Avadhani, D. N.; Prashantha, S. C.; Nagabhushana, H.; Sharma, S. C.; Nagabhushana, B. M.; Nagaswarupa, H. P.; Premkumar, H. B.

    2014-03-01

    Nanoparticles of Eu3+ doped (0-9 mol%) MgO were prepared using low temperature (400 °C) solution combustion technique with metal nitrate as precursor and glycine as fuel. The powder X-ray diffraction (PXRD) patterns of the as-formed products show single cubic phase and no further calcination was required. The crystallite size was obtained using Scherer's formula and was found to be 5-6 nm. The effect of Eu3+ ions on luminescence characteristics of MgO was studied and the results were discussed in detail. These phosphors exhibit bright red emission upon 395 nm excitation. The characteristic photoluminescence (PL) emission peaks at ∼580, 596, 616, 653, 696 and 706 nm (5D0 → 7Fj= 0, 1, 2, 3, 4) were recorded due to Eu3+ ions. The electronic transition corresponding to 5D0 → 7F2 of Eu3+ ions (616 nm) was stronger than the magnetic dipole transition corresponding to 5D0 → 7F1 of Eu3+ ions (596 nm). The international commission on illumination (CIE) chromaticity co-ordinates were calculated from emission spectra, the values (x, y) were very close to national television system committee (NTSC) standard value of red emission. Therefore the present phosphor was highly useful for display applications.

  12. Plasmon resonance enhanced temperature-dependent photoluminescence of Si-V centers in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shaoheng [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Song, Jie; Wang, Qiliang; Liu, Junsong; Li, Hongdong, E-mail: hdli@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Zhang, Baolin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2015-11-23

    Temperature dependent optical property of diamond has been considered as a very important factor for realizing high performance diamond-based optoelectronic devices. The photoluminescence feature of the zero phonon line of silicon-vacancy (Si-V) centers in Si-doped chemical vapor deposited single crystal diamond (SCD) with localized surface plasmon resonance (LSPR) induced by gold nanoparticles has been studied at temperatures ranging from liquid nitrogen temperature to 473 K, as compared with that of the SCD counterpart in absence of the LSPR. It is found that with LSPR the emission intensities of Si-V centers are significantly enhanced by factors of tens and the magnitudes of the redshift (width) of the emissions become smaller (narrower), in comparison with those of normal emissions without plasmon resonance. More interestingly, these strong Si-V emissions appear remarkably at temperatures up to 473 K, while the spectral feature was not reported in previous studies on the intrinsic Si-doped diamonds when temperatures are higher than room temperature. These findings would lead to reaching high performance diamond-based devices, such as single photon emitter, quantum cryptography, biomarker, and so forth, working under high temperature conditions.

  13. Efficient photoluminescence of Dy3+ at low concentrations in nanocrystalline ZrO2

    International Nuclear Information System (INIS)

    Diaz-Torres, L.A.; Rosa, E. de la; Salas, P.; Romero, V.H.; Angeles-Chavez, C.

    2008-01-01

    Nanocrystalline ZrO 2 :Dy 3+ were prepared by sol-gel and the structural and photoluminescence properties characterized. The crystallite size ranges from 20 to 50 nm and the crystalline phase is a mixture of tetragonal and monoclinic structure controlled by dopant concentration. Strong white light produced by the host emission band centered at ∼460 nm and two strong Dy 3+ emission bands, blue (488 nm) and yellow (580 nm), under direct excitation at 350 nm were observed. The highest efficiency was obtained for 0.5 mol% of Dy 3+ . Emission is explained in terms of high asymmetry of the host suggesting that Dy 3+ are substituted mainly into Zr 4+ lattice sites at the crystallite surface. Luminescence quenching is explained in terms of cross-relaxation of intermediate Dy 3+ levels. - Graphical abstract: White light emission from ∼70 nm ZrO 2 :Dy 3+ nanocrystals. The highest efficiency was obtained for 0.5 mol% of dopant and the dominant crystalline structure was monoclinic

  14. Size Controlled CaF2 Nanocubes and Their Dosimetric Properties Using Photoluminescence Technique

    Directory of Open Access Journals (Sweden)

    Najlaa D. Alharbi

    2015-01-01

    Full Text Available A new synthetic chemical coprecipitation route for the preparation of well-crystallized size controlled nano- and microcrystalline cubes of CaF2 is reported. Crystalline cubes in the range of 2 μm–20 nm could be synthesized and their sizes were controlled by varying the solvent : cosolvent ratio. The as-synthesized CaF2 nanocubes were characterized by different techniques. Photoluminescence (PL emission spectrum of CaF2 nanocrystalline powder showed strong emission band at 415 nm. Moreover, the effect of Eu as a dopant on the emission spectrum of CaF2 was investigated. This dopant was found to get incorporated in its Eu2+ and Eu3+ forms. The as-produced nanocubes were exposed to UV irradiation and the corresponding PL emission was studied. Excellent results are obtained, where CaF2:Eu nanocubes were found to be highly sensitive and might be suitable for esteeming the doses of UV irradiation using the PL technique.

  15. Impact of thiol and amine functionalization on photoluminescence properties of ZnO films

    International Nuclear Information System (INIS)

    Jayalakshmi, G.; Saravanan, K.; Balasubramanian, T.

    2013-01-01

    In the present study, we have investigated surface functionalization of ZnO films with dodecanethiol (Thiol) and trioctylamine (amine) by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle (CA) and photoluminescence (PL) measurements. The chemical bondings of thiol and amine with ZnO have been confirmed via the formation of Zn–S and Zn–N bonds by XPS measurements. AFM measurements on ZnO films before and after surface functionalization with thiol and amine provide evidence for the successful functionalization of thiol and amine on ZnO surfaces without any island formation. The CA measurements on ZnO films before and after surface functionalization with thiol and amine show the hydrophobic nature. PL measurements of thiol and amine functionalized ZnO show enhancements of UV emission and quenching of visible emission. The enhanced UV emissions in thiol and amine functionalized ZnO films suggest that the surface defects such as oxygen vacancies are passivated by thiol and amine functionalization. -- Highlights: ► Surface functionalization is a new approach to reduce surface dependent non-radiative process. ► Oxygen vacancies are passivated on surface functionalization. ► Thiol and amine functionalized ZnO show enhancements of UV emission

  16. Photodissociation of gaseous CH3COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

    International Nuclear Information System (INIS)

    Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen

    2013-01-01

    Upon one-photon excitation at 248 nm, gaseous CH 3 C(O)SH is dissociated following three pathways with the products of (1) OCS + CH 4 , (2) CH 3 SH + CO, and (3) CH 2 CO + H 2 S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state 1 (n O , π * CO ) has a radiative lifetime of 249 ± 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 × 10 −10 cm 3 molecule −1 s −1 . Among the primary dissociation products, a fraction of the CH 2 CO moiety may undergo further decomposition to CH 2 + CO, of which CH 2 is confirmed by reaction with O 2 producing CO 2 , CO, OH, and H 2 CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 ± 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

  17. Thermally enhanced photoluminescence for energy harvesting: from fundamentals to engineering optimization

    Science.gov (United States)

    Kruger, N.; Kurtulik, M.; Revivo, N.; Manor, A.; Sabapathy, T.; Rotschild, C.

    2018-05-01

    The radiance of thermal emission, as described by Planck’s law, depends only on the emissivity and temperature of a body, and increases monotonically with the temperature rise at any emitted wavelength. Non-thermal radiation, such as photoluminescence (PL), is a fundamental light–matter interaction that conventionally involves the absorption of an energetic photon, thermalization, and the emission of a redshifted photon. Such a quantum process is governed by rate conservation, which is contingent on the quantum efficiency. In the past, the role of rate conservation for significant thermal excitation had not been studied. Recently, we presented the theory and an experimental demonstration that showed, in contrast to thermal emission, that the PL rate is conserved when the temperature increases while each photon is blueshifted. A further rise in temperature leads to an abrupt transition to thermal emission where the photon rate increases sharply. We also demonstrated how such thermally enhanced PL (TEPL) generates orders of magnitude more energetic photons than thermal emission at similar temperatures. These findings show that TEPL is an ideal optical heat pump that can harvest thermal losses in photovoltaics with a maximal theoretical efficiency of 70%, and practical concepts potentially reaching 45% efficiency. Here we move the TEPL concept onto the engineering level and present Cr:Nd:YAG as device grade PL material, absorbing solar radiation up to 1 μm wavelength and heated by thermalization of energetic photons. Its blueshifted emission, which can match GaAs cells, is 20% of the absorbed power. Based on a detailed balance simulation, such a material coupled with proper photonic management can reach 34% power conversion efficiency. These results raise confidence in the potential of TEPL becoming a disruptive technology in photovoltaics.

  18. Defect states in microcrystalline silicon probed by photoluminescence spectroscopy

    International Nuclear Information System (INIS)

    Merdzhanova, T.; Carius, R.; Klein, S.; Finger, F.; Dimova-Malinovska, D.

    2006-01-01

    Photoluminescence (PL) spectroscopy is used to investigate defects and localized band tail states within the band gap of hydrogenated microcrystalline silicon (μc-Si:H) prepared by plasma enhanced chemical vapor deposition (PECVD) and hot wire chemical vapor deposition (HWCVD). The effect of the substrate temperature (T S ), which influences mainly the defect density, and silane concentration (SC), as Key parameter to control the microstructure of the material were varied. In high quality μc-Si:H films (T S = 185-200 deg. C) a PL band ('μc'-Si-band) is observed at ∼ 0.9-1.05 eV which is attributed to radiative recombination via localized band tail states in the microcrystalline phase. In μc-Si:H films prepared at higher T S (> 300 deg. C), an additional PL band at ∼ 0.7 eV with a width of ∼ 0.17 eV is found for both PECVD and HWCVD material. This band maintains its position at ∼ 0.7 eV with increasing SC in contrast to the observed shift of the 'μc'-Si-band to higher energies. Studies of the temperature dependences of the PL peak energy and intensity for the two bands show: (i) the PL band at 0.7 eV remains unaffected upon increasing temperature, while the 'μc'-Si-band shifts to lower energies (ii) a much weaker quenching for the 0.7 eV band compared to the 'μc'-Si-band. It was also found that the PL band at 0.7 eV exhibits a slightly stronger temperature dependence of the PL intensity compared to 'defect' band at 0.9 eV in a-Si:H suggesting similar recombination transition via deeper trap states. Due to a similar PL properties of the emission band previously observed in Czochralski-grown silicon (Cz-Si), the 0.7 eV band in μc-Si:H is assigned tentatively to defect-related transitions in the crystalline phase

  19. Influence of annealing temperature on Raman and photoluminescence spectra of electron beam evaporated TiO₂ thin films.

    Science.gov (United States)

    Vishwas, M; Narasimha Rao, K; Chakradhar, R P S

    2012-12-01

    Titanium dioxide (TiO(2)) thin films were deposited on fused quartz substrates by electron beam evaporation method at room temperature. The films were annealed at different temperatures in ambient air. The surface morphology/roughness at different annealing temperatures were analyzed by atomic force microscopy (AFM). The crystallinity of the film has improved with the increase of annealing temperature. The effect of annealing temperature on optical, photoluminescence and Raman spectra of TiO(2) films were investigated. The refractive index of TiO(2) films were studied by envelope method and reflectance spectra and it is observed that the refractive index of the films was high. The photoluminescence intensity corresponding to green emission was enhanced with increase of annealing temperature. The peaks in Raman spectra depicts that the TiO(2) film is of anatase phase after annealing at 300°C and higher. The films show high refractive index, good optical quality and photoluminescence characteristics suggest that possible usage in opto-electronic and optical coating applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Green Nanotechnology from Waste Carbon-Polyaniline Composite: Generation of Wavelength-Independent Multiband Photoluminescence for Sensitive Ion Detection

    KAUST Repository

    Goswami, Sumita

    2017-12-11

    This study reports on the qualitative analysis of photoluminescence effect generated from waste carbon of cooking oven by facile cost-effective material engineering. The waste carbon product as a form of carbon nanoparticles (CNPs) is incorporated within a conjugate polymer, namely, polyaniline (PANI) to produce CNP-PANI composites that have shown excitation-wavelength-independent triple-band photoluminescence emission effect and highly sensitive Fe+3 ion detection ability. Herein the waste carbon material, while functionalized within the conjugated polymer, needs no further acid treatment or surface modification thus making the process cheaper, environmentally benign, and useful for green nanotechnology. The excitation-wavelength-independent unique triple-band photoluminescence spectrum is the direct consequence of carbon–polyaniline synergy in π–π transition and the surface passivation of CNPs by the [BOND]NH2 group rich aniline during in-situ polymerization. The current scenario has been studied for the samples prepared with different CNP concentrations for different reaction times and discussed in details with supportive physico-chemical characterizations. Moreover, the present study has demonstrated that the current material can be used as a fluorescent sensing platform for Fe+3 ions with high sensitivity and selectivity criteria where the detection limit of the sensing probe has a value as low as 12 × 10−9 nM.

  1. A unique photofunction of YVO4:Bi3+,Eu3+ nanophosphor: Photoluminescent indication for photochemical decomposition of polyurethane

    International Nuclear Information System (INIS)

    Hara, Hiroki; Takeshita, Satoru; Isobe, Tetsuhiko; Sawayama, Tomohiro; Niikura, Seiji

    2013-01-01

    Highlights: ► A composite film of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor and polyurethane was prepared. ► The composite film exhibits a unique photophysicochemical behavior. ► The nanophosphor shows red photoluminescence under near-UV light irradiation. ► The nanophosphor also acts as a photooxidative decomposer of polyurethane. ► Luminescent intensity becomes an indicator for the decomposition of polyurethane. -- Abstract: We have developed a transparent composite film consisting of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor and polyurethane resin which exhibits unique photophysicochemical behavior. The nanophosphor shows red photoluminescence through f–f transitions of Eu 3+ under near-UV irradiation. The emission intensity drops to half of the initial value after continuous irradiation for 23 h. As shown by electron spin resonance spectroscopy, this decrease in the emission intensity is caused by the formation of V 4+ defects. In addition, thermal analysis and Fourier transform infrared spectroscopy show that the amount of the organic species in the film decreases from 58 to 25 wt% after 23 h. These results indicate that the nanophosphor promotes photooxidative decomposition of the polyurethane resin, while some of the V 5+ ions in YVO 4 are converted to V 4+ ions by photoreduction. Prolonged irradiation for 96 h leads to complete decomposition of the polyurethane and the disappearance of the V 4+ defects, resulting in the recovery of the emission intensity. These findings suggest that the photoluminescence of YVO 4 :Bi 3+ ,Eu 3+ nanophosphor can be used to detect the photooxidative decomposition of polyurethane

  2. Strong broad green UV-excited photoluminescence in rare earth (RE = Ce, Eu, Dy, Er, Yb) doped barium zirconate

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Ciudad de Mexico, D. F. 07730 (Mexico); Meza, O. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A. C., Leon, Gto. 37150 (Mexico)

    2011-10-25

    Highlights: > Trivalent rare earth (RE) substitution on Zr{sup 4+} sites in BaZrO{sub 3} lead to band gap narrowing. > RE substitution lead to enhanced blue-green intrinsic emission of nanocrystalline BaZrO{sub 3} > Blue-green hue of BaZrO3:RE depends on RE dopant and excitation UV wavelength > BaZrO3: Dy{sup 3+} PL chromatic coordinates correspond to pure white color coordinates of CIE 1931 model - Abstract: The wet synthesis hydrothermal method at 100 deg. C was used to elaborate barium zirconate (BaZrO{sub 3}) unpurified with 0.5 mol% of different rare earth ions (RE = Yb, Er, Dy, Eu, Ce). Morphological, structural and UV-photoluminescence properties depend on the substituted rare earth ionic radii. While the crystalline structure of RE doped BaZrO{sub 3} remains as a cubic perovskite for all substituted RE ions, its band gap changes between 4.65 and 4.93 eV. Under 267 nm excitation the intrinsic green photoluminescence of the as synthesized BaZrO{sub 3}: RE samples is considerably improved by the substitution on RE ions. For 1000 deg. C annealed samples, under 267 nm, the photoluminescence is dominated by the intrinsic BZO emission. It is interesting to notice that Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+} doped samples present whitish emissions that might be useful for white light generation under 267 nm excitation. CIE color coordinates are reported for all samples.

  3. Synthesis of YVO4:Eu3+/YBO3Heteronanostructures with Enhanced Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Hu Haihua

    2009-01-01

    Full Text Available Abstract Novel YVO4:Eu3+/YBO3core/shell heteronanostructures with different shell ratios (SRs were successfully prepared by a facile two-step method. X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the heteronanostructures. Photoluminescence (PL study reveals that PL efficiency of the YVO4:Eu3+nanocrystals (cores can be improved by the growth of YBO3nanocoatings onto the cores to form the YVO4:Eu3+/YBO3core/shell heteronanostructures. Furthermore, shell ratio plays a critical role in their PL efficiency. The heteronanostructures (SR = 1/7 exhibit the highest PL efficiency; its PL intensity of the5D0–7F2emission at 620 nm is 27% higher than that of the YVO4:Eu3+nanocrystals under the same conditions.

  4. On the phenomenon of large photoluminescence red shift in GaN nanoparticles

    KAUST Repository

    Ben Slimane, Ahmed

    2013-07-01

    We report on the observation of broad photoluminescence wavelength tunability from n-type gallium nitride nanoparticles (GaN NPs) fabricated using the ultraviolet metal-assisted electroless etching method. Transmission and scanning electron microscopy measurements performed on the nanoparticles revealed large size dispersion ranging from 10 to 100 nm. Nanoparticles with broad tunable emission wavelength from 362 to 440 nm have been achieved by exciting the samples using the excitation power-dependent method. We attribute this large wavelength tunability to the localized potential fluctuations present within the GaN matrix and to vacancy-related surface states. Our results show that GaN NPs fabricated using this technique are promising for tunable-color-temperature white light-emitting diode applications. © 2013 Slimane et al.; licensee Springer.

  5. Characterization of photoluminescent europium doped yttrium oxide thin-films prepared by metallorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    McKittrick, J.; Bacalski, C.F.; Hirata, G.A.; Hubbard, K.M.; Pattillo, S.G.; Salazar, K.V.; Trkula, M.

    1998-01-01

    Europium doped yttrium oxide, (Y 1-x Eu x ) 2 O 3 , thin-films were deposited on silicon and sapphire substrates by metallorganic chemical vapor deposition (MOCVD). The films were grown in a MOCVD chamber reacting yttrium and europium tris(2,2,6,6-tetramethyl-3,5,-heptanedionates) precursors in an oxygen atmosphere at low pressures (5 Torr) and low substrate temperatures (500--700 C). The films deposited at 500 C were flat and composed of nanocrystalline regions of cubic Y 2 O 3 , grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600 C developed from the flat, nanocrystalline morphology into a plate-like growth morphology oriented in the [111] with increasing deposition time. Monoclinic Y 2 O 3 :Eu 3+ was observed in x-ray diffraction for deposition temperatures ≥600 C on both (111) Si and (001) sapphire substrates. This was also confirmed by the photoluminescent emission spectra

  6. Formation and characterization of varied size germanium nanocrystals by electron microscopy, Raman spectroscopy, and photoluminescence

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Liu, Chuan

    2011-01-01

    Germanium nanocrystals are being extensively examined. Their unique optical properties (brought about by the quantum confinement effect) could potentially be applied in wide areas of nonlinear optics, light emission and solid state memory etc. In this paper, Ge nanocrystals embedded in a SiO2...... matrix were formed by complementary metal-oxide-semiconductor compatible technology, e.g. plasma enhanced chemical vapour deposition and annealing. Different sizes of the Ge nanocrystals were prepared and analyzed by transmission electron microscopy with respect to their size, distribution...... and crystallization. The samples of different size Ge nanocrystals embedded in the SiO2 matrix were characterized by Raman spectroscopy and photoluminescence. Interplayed size and strain effect of Ge nanocystals was demonstrated by Raman spectroscopy after excluding the thermal effect with proper excitation laser...

  7. Photoluminescence study of novel phosphorus-doped ZnO nanotetrapods synthesized by chemical vapour deposition

    International Nuclear Information System (INIS)

    Yu Dongqi; Hu Lizhong; Qiao Shuangshuang; Zhang Heqiu; Fu Qiang; Chen Xi; Sun Kaitong; Len, Song-En Andy; Len, L K

    2009-01-01

    Novel phosphorus-doped and undoped single crystal ZnO nanotetrapods were fabricated on sapphire by a simple chemical vapour deposition method, using phosphorus pentoxide (P 2 O 5 ) as the dopant source. The optical properties of the samples were investigated by photoluminescence (PL) spectroscopy. Low-temperature PL measurements of phosphorus-doped and undoped samples were compared, and the results indicated a decrease in deep level defects due to the incorporation of a phosphorus acceptor dopant. The PL spectrum of the phosphorus-doped sample at 10 K exhibited several acceptor-bound exciton related emission peaks. The effect of phosphorus doping on the optical characteristics of the samples was investigated by excitation intensity and temperature dependent PL spectra. The acceptor-binding energies of the phosphorus dopant were estimated to be about 120 meV, in good agreement with the corresponding theoretical and experimental values in phosphorus-doped ZnO films and nanowires.

  8. Photoluminescence of Mg{sub 2}Si films fabricated by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Yang-Fang [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Xie, Quan, E-mail: qxie@gzu.edu.cn [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xiao, Qing-Quan [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Engineering Center for Avionics Electrical and Information Network of Guizhou Provincial Colleges and Universities, Anshun 561000 (China); Chen, Qian; Fan, Meng-Hui [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xie, Jing [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China)

    2017-05-01

    Highlights: • High quality Mg{sub 2}Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg{sub 2}Si films was reported. • The Mg{sub 2}Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg{sub 2}Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg{sub 2}Si-based light-emitting devices, Mg{sub 2}Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg{sub 2}Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg{sub 2}Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg{sub 2}Si film on Si (111) displays polycrystalline structure, whereas Mg{sub 2}Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg{sub 2}Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg{sub 2}Si films was observed for the first time. The PL emission wavelengths of Mg{sub 2}Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg{sub 2}Si films on glass substrate is much larger than that of Mg

  9. Strategy for synthesizing quantum dot-layered double hydroxide nanocomposites and their enhanced photoluminescence and photostability.

    Science.gov (United States)

    Cho, Seungho; Jung, Sungwook; Jeong, Sanghwa; Bang, Jiwon; Park, Joonhyuck; Park, Youngrong; Kim, Sungjee

    2013-01-08

    Layered double hydroxide-quantum dot (LDH-QD) composites are synthesized via a room temperature LDH formation reaction in the presence of QDs. InP/ZnS (core/shell) QD, a heavy metal free QD, is used as a model constituent. Interactions between QDs (with negative zeta potentials), decorated with dihydrolipoic acids, and inherently positively charged metal hydroxide layers of LDH during the LDH formations are induced to form the LDH-QD composites. The formation of the LDH-QD composites affords significantly enhanced photoluminescence quantum yields and thermal- and photostabilities compared to their QD counterparts. In addition, the fluorescence from the solid LDH-QD composite preserved the initial optical properties of the QD colloid solution without noticeable deteriorations such as red-shift or deep trap emission. Based on their advantageous optical properties, we also demonstrate the pseudo white light emitting diode, down-converted by the LDH-QD composites.

  10. On the phenomenon of large photoluminescence red shift in GaN nanoparticles

    KAUST Repository

    Ben Slimane, Ahmed; Anjum, Dalaver H.; Elafandy, Rami T.; Najar, Adel; Ng, Tien Khee; San Roman Alerigi, Damian; Ooi, Boon S.

    2013-01-01

    We report on the observation of broad photoluminescence wavelength tunability from n-type gallium nitride nanoparticles (GaN NPs) fabricated using the ultraviolet metal-assisted electroless etching method. Transmission and scanning electron microscopy measurements performed on the nanoparticles revealed large size dispersion ranging from 10 to 100 nm. Nanoparticles with broad tunable emission wavelength from 362 to 440 nm have been achieved by exciting the samples using the excitation power-dependent method. We attribute this large wavelength tunability to the localized potential fluctuations present within the GaN matrix and to vacancy-related surface states. Our results show that GaN NPs fabricated using this technique are promising for tunable-color-temperature white light-emitting diode applications. © 2013 Slimane et al.; licensee Springer.

  11. Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence

    International Nuclear Information System (INIS)

    Duraia, El-Shazly M.; Mansurov, Z.A.; Tokmolden, S.; Beall, Gary W.

    2010-01-01

    In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm -1 and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

  12. Structural and photoluminescence studies of pure and Eu3+ doped Y2O3 oxide nanoparticles

    International Nuclear Information System (INIS)

    Packiyaraj, P.; Thangadurai, P.

    2013-01-01

    Pure and Eu 3+ doped Y 2 O 3 nanoparticles were synthesized by a hydrolysis assisted co-precipitation method. Structural characterization was carried out by X-ray diffraction. The as-prepared Eu:Y 2 O 3 was amorphous yttrium hydroxides in nature and become crystalline Y 2 O 3 once annealed at 600℃ and 900℃. The particle size (13-23 nm) was dependent on annealing temperatures and Eu 3+ ion concentration. Photoluminescence studies showed weak emission bands at 581, 587, 593, and 599 nm, corresponding to the 5 D 0 → 7 F 1 transitions, and sharp peaks with a maximum intensity occurring at 611 nm, due to the 5 D 0 → 7 F 2 transitions of Eu 3+ . (author)

  13. Study of photoluminescence from annealed bulk-ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoneta, M.; Ohishi, M.; Saito, H. [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005 (Japan); Yoshino, K. [Department of Electrical and Electronic Engineering, Miyazaki University, 1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192 (Japan); Honda, M. [Faculty of Science, Naruto University of Education, 748 Nakajima, Takashima, Naruto-cho, Naruto-shi 772-8502 (Japan)

    2006-03-15

    We have investigated the influence of rapid thermal annealing on the photoluminescence of bulk-ZnO single crystal. As-grown ZnO wafer, illuminated by 325 nm ultraviolet light at 4.2 K, emitted the visible luminescence of pale green centered of 2.29 eV. The luminescence was observed by the anneal at the temperature range between 400 C and 1000 C, however, its intensity decreased with anneal temperature. The free-exciton and the 2.18 eV emission line were obtained by the anneal at 1200 C for 60 sec. From the X-ray diffraction and the surface morphology measurements, the improvement of the crystallinity of bulk-ZnO crystal were confirmed. We suggest that a rapid thermal annealing technique is convenience to improve the the quality of bul-ZnO single crystals. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M., E-mail: duraia_physics@yahoo.co [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Mansurov, Z.A. [Al-Farabi Kazakh National University, Almaty (Kazakhstan); Tokmolden, S. [Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Beall, Gary W. [Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States)

    2010-02-15

    In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm{sup -1} and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

  15. N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

    Science.gov (United States)

    Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

    2016-02-01

    An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Sonochemical Synthesis of Photoluminescent Nanoscale Eu(III-Containing Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Cheng-an TAO

    2015-11-01

    Full Text Available Nanoscale lanthanide-containing metal-organic frameworks (MOFs have more and more interest due to their great properties and potential applications, but how to construct them easily is still challenging. Here, we present a facile and rapid synthesis of Eu(III-containing Nanoscale MOF (denoted as NMOF under ultrasonic irradiation. The effect of the ratio and the addition order of metal ions and linkers on the morphology and size of MOFs was investigated. It is found that both of the ratio and the addition order can affect the morphology and size of 1.4-benzenedicarboxylic acid(H2BDC -based MOFs, but they show no evident influence on that of H2aBDC-based MOFs. The former exhibit typical emission bands of Eu(III ions, while the latter only show the photoluminescent properties of ligands.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9695

  17. Microwave-assisted synthesis and photoluminescence properties of ...

    Indian Academy of Sciences (India)

    2017-11-11

    Nov 11, 2017 ... The photoluminescence property was studied by near-UV (nUV) excitation. The XRD .... spectrofluorimeter equipped with a 450-W Xenon lamp, in the range of .... nUV-excited RGB tricolour LED for production of white light.

  18. Characterization and photoluminescence studies of CdTe ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The major objective of this work was to detect the change of photoluminescence (PL) intensity of. CdTe nanoparticles (NPs) before and after transfer from liquid phase to polystyrene (PS) matrix by electro- spinning technique. Thio-stabilized CdTe NPs were first synthesized in aqueous, then enwrapped by cetyl-.

  19. Optical properties and photoluminescence of tetrahexyl-sexithiophene allotropes

    NARCIS (Netherlands)

    Botta, C; Destri, S; Porzio, W; Bongiovanni, G; Loi, MA; Mura, A; Tubino, R

    2001-01-01

    The optical absorption, Raman scattering and photoluminescence of two phases of tetrahexyl-sexithiophene (4HT6) display properties coherently related to the different molecular conformations imposed by the chain packing. We analyse the temperature dependence of the optical properties of a sample in

  20. Photoluminescence Enhancement in Formamidinium Lead Iodide Thin Films

    NARCIS (Netherlands)

    Fang, Hong-Hua; Wang, Feng; Adjokatse, Sampson; Zhao, Ni; Loi, Maria Antonietta

    2016-01-01

    Formamidinium lead iodide (FAPbI(3)) has a broader absorption spectrum and better thermal stability than the most famous methylammonium lead iodide, thus exhibiting great potential for photovoltaic applications. In this report, the light-induced photoluminescence (PL) evolution in FAPbI(3) thin

  1. Gold nanoparticles–gelatinhybrid fibers with bright photoluminescence

    DEFF Research Database (Denmark)

    Liu, Shuiping; Tan, Lianjiang; Li, Xiaoqiang

    2014-01-01

    acid and gave rise to in situ synthesis of GNPs in the spinning solutions. The GNPs–gelatin fibers were fabricated by electrospinning the spinning solutions. The GNPs were encapsulated in the fibers, which endowed the fibers photoluminescence (PL) characteristics. A variety of experiments were...

  2. Chemical Changes and photoluminescence properties of UV modified polypyrrole

    Czech Academy of Sciences Publication Activity Database

    Galář, P.; Dzurňák, B.; Malý, P.; Čermák, Jan; Kromka, Alexander; Omastová, M.; Rezek, Bohuslav

    2013-01-01

    Roč. 8, č. 1 (2013), s. 57-70 ISSN 1452-3981 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : photoluminescence * polypyrrole * monocrystalline diamond Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.956, year: 2013 http://www.electrochemsci.org/papers/vol8/80100057.pdf

  3. Photoluminescence studies of Li-doped Si nanocrystals

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Eva; Vacík, Jiří; Holý, V.; Pelant, Ivan

    2013-01-01

    Roč. 3, č. 14 (2013), s. 1-7 ISSN 1847-9804 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : Si nanocrystals * photoluminescence * doping * Li-ion batteries Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.949, year: 2013

  4. The effect of O2 partial pressure on the photoluminescence of ZnO thin films grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Lu, Y.M.; Li, X.P.; Su, S.C.; Cao, P.J.; Jia, F.; Han, S.; Zeng, Y.X.; Liu, W.J.; Zhu, D.L.

    2014-01-01

    In this paper, photoluminescence (PL) of ZnO thin films prepared on c-Al 2 O 3 substrates by the pulsed laser deposition (PLD) method at different O 2 partial pressures is investigated. For all samples, a narrow ultraviolet (UV) emission and a broad visible emission can be observed at room-temperature (RT). With increasing O 2 partial pressures from 0.2 to 5 Pa, the intensity ratio of the UV to visible emissions increases, and the energy positions of the UV emission band shift to the high energy side. It is noted that the visible part includes two emission bands of green luminescence (GL) and yellow luminescence (YL), in which the GL emission is strong at low oxygen pressure and the YL emission becomes dominant at high O 2 partial pressures. The temperature-dependent PL spectra show that the UV emission is composed of two bands labeled FX and FA. The dependences and possible assignments of these PL bands are briefly discussed. - Highlights: • We confirmed that the RT UV emission band is due to two transitions of the FX and FA. • The intensity of the FX and FA emission bands strongly depends on oxygen partial pressures. • We deduced that the acceptor-like defects located in the grain boundaries are responsible for the FA emission. • The visible emission includes the GL related to V O and the YL related to V Zn or O i . • The GL emission strongly affects the UV emission

  5. MARKETING CHANNELS

    Directory of Open Access Journals (Sweden)

    Ljiljana Stošić Mihajlović

    2014-07-01

    Full Text Available Marketing channel is a set of entities and institutions, completion of distribution and marketing activities, attend the efficient and effective networking of producers and consumers. Marketing channels include the total flows of goods, money and information taking place between the institutions in the system of marketing, establishing a connection between them. The functions of the exchange, the physical supply and service activities, inherent in the system of marketing and trade. They represent paths which products and services are moving after the production, which will ultimately end up buying and eating by the user.

  6. The effects of xenon ion irradiation on the photoluminesce behavior of poly(p-cresolformaldeyde)/diazonaphtoquinone thin films

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Irene T.S. [Depto. de Quimica Analitica e Inorganica, Instituto de Quimica e Geociencias, UFPel, Capao do Leao s/n, 96010-900, Pelotas, RS (Brazil)], E-mail: irene@ufpel.edu.br; Zawislak, F.C.; Balzaretti, Naira [Instituto de Fisica, UFRGS, Caixa Postal 15051, 91501-970 Porto Alegre (Brazil); Samios, D. [Instituto de Quimica, UFRGS, 91501-970 Porto Alegre (Brazil); Sias, U. [Centro Federal de Educacao Tecnologica de Pelotas, 96015-360 Pelotas (Brazil)

    2007-10-15

    In the present paper, we investigate the origin of photoluminescence (PL) and the changes in the optical properties: refractive index and absorption coefficient, in poly(p-cresolformaldeyde) and diazonaphtoquinone thin films irradiated with Xe ions. Films 400 nm thick have been irradiated with 800 keV Xe{sup 2+} ions in a fluence range from 10{sup 13} to 6 x 10{sup 15} Xe cm{sup -2}. The structural modifications were followed by the techniques of nuclear reaction analysis, elastic recoil detection analysis, Rutherford backscattering, Fourier transform infrared and Raman spectroscopies. The PL behavior was characterised with 488 nm excitation wavelength. The pristine films show emission with maxima of the main bands located at 635, 720 and 830 nm. For fluences up to 10{sup 14} Xe cm{sup -2}, the photoluminescence intensity increases with the irradiation fluence. The chain mobility lowering, characterized by the crosslinked structure, explains this behavior in organic systems. Other possible contribution for increasing of PL intensity, at these fluences, is the presence of oxygen trapped in the polymer chains by the dangling bonds. At intermediate and higher fluences, the photoluminescence starts to decrease. At fluences higher than 10{sup 14} Xe cm{sup -2}, irreversible changes of the organic structure occur and they are characterized by large losses of oxygen and hydrogen, transforming the material into amorphous carbon films. The loss of photoluminescent behavior is associated with the light absorption characteristics of the amorphous carbon structure. This conclusion is supported by the observed increase of the refractive indexes and absorption coefficients, obtained in the infrared region, as well as by the Raman results. Also, the effect of irradiation modifying the refractive index in the infrared region suggests the application of these films as waveguide in this region of wavelength.

  7. Growth and temperature dependent photoluminescence of InGaAs quantum dot chains

    International Nuclear Information System (INIS)

    Yang, Haeyeon; Kim, Dong-Jun; Colton, John S.; Park, Tyler; Meyer, David; Jones, Aaron M.; Thalman, Scott; Smith, Dallas; Clark, Ken; Brown, Steve

    2014-01-01

    Highlights: • We examine the optical properties of novel quantum dot chains. • Study shows that platelets evolve into quantum dots during heating of the InGaAs platelets encapsulated with GaAs. • Single stack of quantum dots emits light at room temperature. • Quantum dots are of high quality, confirmed by cross-section TEM images and photoluminescence. • Light emission at room temperature weakens beyond the detection limit when the quantum dots form above the critical annealing temperature. - Abstract: We report a study of growth and photoluminescence from a single stack of MBE-grown In 0.4 Ga 0.6 As quantum dot chains. The InGaAs epilayers were grown at a low temperature so that the resulting surfaces remain flat with platelets even though their thicknesses exceed the critical thickness of the conventional Stranski–Krastanov growth mode. The flat InGaAs layers were then annealed at elevated temperatures to induce the formation of quantum dot chains. A reflection high energy electron diffraction study suggests that, when the annealing temperature is at or below 480 °C, the surface of growth front remains flat during the periods of annealing and growth of a 10 nm thick GaAs capping layer. Surprisingly, transmission electron microscopy images do indicate the formation of quantum dot chains, however, so the dot-chains in those samples may form from precursory platelets during the period of temperature ramping and subsequent capping with GaAs due to intermixing of group III elements. The optical emission from the quantum dot layer demonstrates that there is a critical annealing temperature of 480–500 °C above which the properties of the low temperature growth approach are lost, as the optical properties begin to resemble those of quantum dots produced by the conventional Stranski–Krastanov technique

  8. Time-correlated single-photon counting study of multiple photoluminescence lifetime components of silicon nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Diamare, D., E-mail: d.diamare@ee.ucl.ac.uk [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Wojdak, M. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Lettieri, S. [Institute for Superconductors and Innovative Materials, National Council of Research (CNR-SPIN), Via Cintia 80126, Naples (Italy); Department of Physical Sciences, University of Naples “Federico II”, Via Cintia 80126, Naples (Italy); Kenyon, A.J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom)

    2013-04-15

    We report time-resolved photoluminescence measurements of thin films of silica containing silicon nanoclusters (Si NCs), produced by PECVD and annealed at temperatures between 700 °C and 1150 °C. While the near infrared emission of Si NCs has long been studied, visible light emission has only recently attracted interest due to its very short decay times and its recently-reported redshift with decreasing NCs size. We analyse the PL decay dynamics in the range 450–700 nm with picosecond time resolution using Time Correlated Single Photon Counting. In the resultant multi-exponential decays two dominant components can clearly be distinguished: a very short component, in the range of hundreds of picoseconds, and a nanosecond component. In this wavelength range we do not detect the microsecond component generally associated with excitonic recombination. We associate the nanosecond component to defect relaxation: it decreases in intensity in the sample annealed at higher temperature, suggesting that the contribution from defects decreases with increasing temperature. The origin of the very fast PL component (ps time region) is also discussed. We show that it is consistent with the Auger recombination times of multiple excitons. Further work needs to be done in order to assess the contribution of the Auger-controlled recombinations to the defect-assisted mechanism of photoluminescence. -- Highlights: ► We report time-resolved PL measurements of Si-Ncs embedded in SiO{sub 2} matrix. ► Net decrease of PL with increasing the annealing temperature has been observed. ► Lifetime distribution analysis revealed a multiexponential decay with ns and ps components. ► Ps components are consistent with the lifetime range of the Auger recombination times. ► No evidence for a fast direct transition at the Brillouin zone centre.

  9. A New Star-shaped Carbazole Derivative with Polyhedral Oligomeric Silsesquioxane Core: Crystal Structure and Unique Photoluminescence Property.

    Science.gov (United States)

    Xu, Zixuan; Yu, Tianzhi; Zhao, Yuling; Zhang, Hui; Zhao, Guoyun; Li, Jianfeng; Chai, Lanqin

    2016-01-01

    A new inorganic–organic hybrid material based on polyhedral oligomeric silsesquioxane (POSS) capped with carbazolyl substituents, octakis[3-(carbazol-9-yl)propyldimethylsiloxy]-silsesquioxane (POSS-8Cz), was successfully synthesized and characterized. The X-ray crystal structure of POSS-8Cz were described. The photophysical properties of POSS-8Cz were investigated by using UV–vis,photoluminescence spectroscopic analysis. The hybrid material exhibits blue emission in the solution and the solid film.The morphology and thermal stablity properties were measured by X-ray diffraction (XRD) and TG-DTA analysis.

  10. Improving stability of photoluminescence of ZnSe thin films grown by molecular beam epitaxy by incorporating Cl dopant

    International Nuclear Information System (INIS)

    Wang, J. S.; Shen, J. L.; Chen, W. J.; Tsai, Y. H.; Wang, H. H.; Yang, C. S.; Chen, R. H.; Tsai, C. D.

    2011-01-01

    This investigation studies the effect of chlorine (Cl) dopant in ZnSe thin films that were grown by molecular beam epitaxy on their photoluminescence (PL) and the stability thereof. Free excitonic emission was observed at room-temperature in the Cl-doped sample. Photon irradiation with a wavelength of 404 nm and a power density of 9.1 W/cm 2 has a much stronger effect on PL degradation than does thermal heating to a temperature of 150 deg. C. Additionally, this study shows that the generation of nonradiative centers by both photon irradiation and thermal heating can be greatly inhibited by incorporating Cl dopant.

  11. Suppression of the green photoluminescence band in ZnO embedded into porous opal by spray pyrolysis

    International Nuclear Information System (INIS)

    Abrarov, S.M.; Yuldashev, Sh.U.; Lee, S.B.; Kang, T.W.

    2004-01-01

    The photoluminescence (PL) and transmittance characteristics of the zinc oxide embedded into voids of FCC sub-micron packed silicon dioxide spheres by using technologically simple and inexpensive spray pyrolysis are reported. The uniform formation of ZnO nanocrystalline particles inside of the porous opal takes place after deposition in aqueous solution with zinc nitrite hexahydride precursor followed by thermal annealing. The decrease of green PL is observed due to the inhibition of spontaneous emission through oxygen vacancies in ZnO. The strong red shift of the transmittance characteristics signifies the essential filling of voids in the opal matrix

  12. Photoluminescence of Hexagonal ZnO Nanorods Hydrothermally Grown on Zn Foils in KOH Solutions with Different Values of Basicity

    Directory of Open Access Journals (Sweden)

    Nuengruethai Ekthammathat

    2013-01-01

    Full Text Available Aligned hexagonal ZnO nanorods on pure Zn foils were hydrothermally synthesized in 30 mL solutions containing 0.05–0.50 g KOH. The products were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and photoluminescence (PL spectroscopy. In this research, wurtzite hexagonal ZnO nanorods grown along the [002] direction with green light emission at 541 nm caused by singly ionized oxygen vacancies inside were detected.

  13. Carborane-stilbene dyads: the influence of substituents and cluster isomers on photoluminescence properties.

    Science.gov (United States)

    Ferrer-Ugalde, A; Cabrera-González, J; Juárez-Pérez, E J; Teixidor, F; Pérez-Inestrosa, E; Montenegro, J M; Sillanpää, R; Haukka, M; Núñez, R

    2017-02-14

    Two novel styrene-containing meta-carborane derivatives substituted at the second carbon cluster atom (C c ) with either a methyl (Me) or a phenyl (Ph) group are introduced herein along with a new set of stilbene-containing ortho- (o-) and meta- (m-) carborane dyads. The latter set of compounds have been prepared from styrene-containing carborane derivatives via a Heck coupling reaction. High regioselectivity has been achieved for these compounds by using a combination of palladium complexes [Pd 2 (dba) 3 ]/[Pd(t-Bu 3 P) 2 ] as a catalytic system, yielding exclusively E isomers. All compounds have been fully characterised and the crystal structures of seven of them were analysed by X-ray diffraction. The absorption spectra of these compounds are similar to those of their respective fluorophore groups (styrene or stilbene), showing a very small influence of the substituent (Me or Ph) linked to the second C c atom or the cluster isomer (o- or m-). On the other hand, fluorescence spectroscopy revealed high emission intensities for Me-o-carborane derivatives, whereas their Ph-o-carborane analogues evidenced an almost total lack of fluorescence, confirming the significant role of the substituent bound to the adjacent C c in o-carboranes. In contrast, all the m-carborane derivatives display similar photoluminescence (PL) behavior regardless of the substituent attached to the second C c , demonstrating its small influence on emission properties. Additionally, m-carborane derivatives are significantly more fluorescent than their o-counterparts, reaching quantum yield values as high as 30.2%. Regarding solid state emission, only stilbene-containing Ph-o-carborane derivatives, which showed very low fluorescence in solution, exhibited notable PL emission in films attributed to aggregation-induced emission. DFT calculations were performed to successfully complement the photoluminescence studies, supporting the experimentally observed photophysical behavior of the styrene and

  14. Synthesis and photoluminescence properties of Sm3+-doped CaWO4 nanoparticles

    International Nuclear Information System (INIS)

    Xiao Qi; Zhou Qitao; Li Ming

    2010-01-01

    The Sm 3+ -doped CaWO 4 nanoparticles were synthesized by hydrothermal method. The room temperature photoluminescence (PL) spectra of Sm 3+ -doped CaWO 4 nanoparticles doped with different Sm 3+ concentrations under 405 nm excitation have been investigated. The PL spectra showed four strong emission peaks at 460, 571, 609, and 653 nm. The first emission peak at 460 nm could be due to a structural defect of the lattice, an oxygen-deficient WO 3 complex. The other three emissions at 571, 609, and 653 nm were due to the f-f forbidden transitions of the 4f electrons of Sm 3+ , corresponding to 4 G 5/2 → 6 H 5/2 (571 nm), 6 H 7/2 (609 nm), and 6 H 9/2 (653 nm), respectively. In addition, the optimum Sm 3+ concentration in CaWO 4 nanoparticles for optical emission was determined to be 1.0%. The Sm 3+4 G 5/2 → 6 H 7/2 (609 nm) emission intensity of Sm 3+ -doped CaWO 4 nanoparticles significantly increased with the increase of Sm 3+ concentration, and showed a maximum when Sm 3+ doping content was 1.0%. If Sm 3+ concentration continued to increase, namely more than 1.0%, the Sm 3+4 G 5/2 → 6 H 7/2 emission intensity would decrease. The present materials might be a promising phosphor for white-light LED applications.

  15. Origin of broad NIR photoluminescence in bismuthate glass and Bi-doped glasses at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Mingying; Zollfrank, Cordt; Wondraczek, Lothar [Lehrstuhl fuer Glas und Keramik, WW3, Friedrich Alexander Universitaet Erlangen-Nuernberg, Martensstrasse 5, D-91058 Erlangen (Germany)], E-mail: mingying.peng@ww.uni-erlangen.de, E-mail: lothar.wondraczek@ww.uni-erlangen.de

    2009-07-15

    Bi-doped glasses with broadband photoluminescence in the near-infrared (NIR) spectral range are presently receiving significant consideration for potential applications in telecommunications, widely tunable fiber lasers and spectral converters. However, the origin of NIR emission remains disputed. Here, we report on NIR absorption and emission properties of bismuthate glass and their dependence on the melting temperature. Results clarify that NIR emission occurs from the same centers as it does in Bi-doped glasses. The dependence of absorption and NIR emission of bismuthate glasses on the melting temperature is interpreted as thermal dissociation of Bi{sub 2}O{sub 3} into elementary Bi. Darkening of bismuthate glass melted at 1300 deg. C is due to the agglomeration of Bi atoms. The presence of Bi nanoparticles is confirmed by transmission electron microscopy, high-resolution energy dispersive x-ray spectroscopy and element distribution mapping. By adding antimony oxide as an oxidation agent to the glass, NIR emission centers can be eliminated and Bi{sup 3+} is formed. By comparing with atomic spectral data, absorption bands at {approx}320 , {approx}500 , 700 , 800 and 1000 nm observed in Bi-doped glasses are assigned to Bi{sup 0} transitions {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 3/2}, {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 1/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 5/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(2) and {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(1), respectively, and broadband NIR emission is assigned to the transition {sup 2}D{sub 3/2}(1){yields}{sup 4}S{sub 3/2}.

  16. Mechanoluminescence, photoluminescence and thermoluminescence studies of SrZrO3:Ce phosphor

    Directory of Open Access Journals (Sweden)

    Neha Tiwari

    2015-01-01

    Full Text Available The present paper reports the synthesis and characterization, photoluminescence thermoluminescence and mechanoluminescence studies of Ce3+ doped SrZrO3 phosphors. The effects of variable concentration of Cerium on meachanoluminescence (ML and photoluminescence behavior were studied. The samples were prepared by combustion a synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. The starting material used for sample preparation are Sr(NO33, Zr(NO33 XH2O and Ce(NO33 6H2O and urea used as a fuel. The prepared sample was characterized by X-ray diffraction technique (XRD with variable concentration of Ce (0.05–0.5 mol%. There is no any phase change found with increase the concentration of Ce. Sample shows orthorhombic structure and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM technique. Mechanoluminescence studies on SrZrO3phosphors doped with Ce and underwent an impulsive deformation with an impact of a piston for Mechanoluminescence (ML investigations. Temporal characteristics in order to investigate about the luminescence centre responsible for ML peak, increasing impact velocity causes more number of electrons will be ionized to reach to the conduction band so there will be more number of electrons available to be recombined at recombination or luminescence centre. In photoluminescence study PL emission spectra show the isolated peak position observed at 388 nm near UV region of spectrum due to 5d–4f transition of Ce3+ion.Thermoluminescence study shows doping of Ce3+ ions reduced the TL intensity TL glow curve shows the high fading and less stability when it doped with cerium. The activation energy high for the doped SrZrO3 phosphor means that the trapped electron is highly trapped in trap level. The present study gives the advance application for fracture

  17. Photoluminescence as a tool for characterizing point defects in semiconductors

    Science.gov (United States)

    Reshchikov, Michael

    2012-02-01

    Photoluminescence is one of the most powerful tools used to study optically-active point defects in semiconductors, especially in wide-bandgap materials. Gallium nitride (GaN) and zinc oxide (ZnO) have attracted considerable attention in the last two decades due to their prospects in optoelectronics applications, including blue and ultraviolet light-emitting devices. However, in spite of many years of extensive studies and a great number of publications on photoluminescence from GaN and ZnO, only a few defect-related luminescence bands are reliably identified. Among them are the Zn-related blue band in GaN, Cu-related green band and Li-related orange band in ZnO. Numerous suggestions for the identification of other luminescence bands, such as the yellow band in GaN, or green and yellow bands in ZnO, do not stand up under scrutiny. In these conditions, it is important to classify the defect-related luminescence bands and find their unique characteristics. In this presentation, we will review the origin of the major luminescence bands in GaN and ZnO. Through simulations of the temperature and excitation intensity dependences of photoluminescence and by employing phenomenological models we are able to obtain important characteristics of point defects such as carrier capture cross-sections for defects, concentrations of defects, and their charge states. These models are also used to find the absolute internal quantum efficiency of photoluminescence and obtain information about nonradiative defects. Results from photoluminescence measurements will be compared with results of the first-principle calculations, as well as with the experimental data obtained by other techniques such as positron annihilation spectroscopy, deep-level transient spectroscopy, and secondary ion mass spectrometry.

  18. Photoluminescence of Sequential Infiltration Synthesized ZnO nanostructures

    Science.gov (United States)

    Ocola, Leonidas; Gosztola, David; Yanguas-Gil, Angel; Connolly, Aine

    We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside polymethylmethacrylate (PMMA) and other polymers. Energy dispersive spectroscopy (EDS) results show that we synthesize ZnO up to 300 nm inside a PMMA film. Photoluminescence data on a PMMA film shows that we achieve a factor of 400X increase in photoluminescence (PL) intensity when comparing a blank Si sample and a 270 nm thick PMMA film, where both were treated with the same 12 alternating cycles of H2O and diethyl zinc (DEZ). PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid polymer-oxide material. We show that patterning does indeed affect the photoluminescence signature of native ZnO. We demonstrate we can track the growth of the ZnO inside the PMMA polymer using both photoluminescence and Raman spectroscopy and determine the point in the process where ZnO is first photoluminescent and also at which point ZnO first exhibits long range order in the polymer. This work was supported by the Department of Energy under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  19. Chemical insight into the origin of red and blue photoluminescence arising from freestanding silicon nanocrystals.

    Science.gov (United States)

    Dasog, Mita; Yang, Zhenyu; Regli, Sarah; Atkins, Tonya M; Faramus, Angelique; Singh, Mani P; Muthuswamy, Elayaraja; Kauzlarich, Susan M; Tilley, Richard D; Veinot, Jonathan G C

    2013-03-26

    Silicon nanocrystals (Si NCs) are attractive functional materials. They are compatible with standard electronics and communications platforms and are biocompatible. Numerous methods have been developed to realize size-controlled Si NC synthesis. While these procedures produce Si NCs that appear identical, their optical responses can differ dramatically. Si NCs prepared using high-temperature methods routinely exhibit photoluminescence agreeing with the effective mass approximation (EMA), while those prepared via solution methods exhibit blue emission that is somewhat independent of particle size. Despite many proposals, a definitive explanation for this difference has been elusive for no less than a decade. This apparent dichotomy brings into question our understanding of Si NC properties and potentially limits the scope of their application. The present contribution takes a substantial step forward toward identifying the origin of the blue emission that is not expected based upon EMA predictions. It describes a detailed comparison of Si NCs obtained from three of the most widely cited procedures as well as the conversion of red-emitting Si NCs to blue emitters upon exposure to nitrogen-containing reagents. Analysis of the evidence is consistent with the hypothesis that the presence of trace nitrogen and oxygen even at the parts per million level in Si NCs gives rise to the blue emission.

  20. Size dependent photoluminescence property of hydrothermally synthesized crystalline carbon quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, S.; Banerjee, D.; Ghorai, U.K.; Das, N.S. [School of Material Science and Nanotechnology Jadavpur University, Kolkata 700032 (India); Chattopadhyay, K.K., E-mail: kalyan_chattopadhyay@yahoo.com [School of Material Science and Nanotechnology Jadavpur University, Kolkata 700032 (India); Thin Film and NanoScience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India)

    2016-10-15

    In this work, simple hydrothermal synthesis of water soluble Carbon quantum dots (CQDs) of different sizes has been reported. The effect of synthesis temperature and synthesis time on the particle size has also been shown. The structures of all the as-prepared samples were studied by field emission scanning electron microscope and high resolution transmission electron microscope. Fourier transformed infrared spectrophotometer analyzes the different bonding present in the sample whereas Raman spectrophotometer quantifies the hybridization state of the prepared samples. UV–vis spectrophotometer gives the variation of absorbance of all the samples with wavelength. Dynamic light scattering study shows the variation of particle size with deposition condition and corresponding zeta potential gives the idea about the stability of the CQD solutions. The photoluminescence (PL) properties of the as prepared CQDs were also studied in detail. It is noticed that with the increase of excitation wavelength, the PL emissions for the different samples were red shifted. The results have been explained in terms of the excitation dependent emission, variations in size of the CQD and presence of different functional groups on the surface of CQDs.

  1. Size dependent photoluminescence property of hydrothermally synthesized crystalline carbon quantum dots

    International Nuclear Information System (INIS)

    Sarkar, S.; Banerjee, D.; Ghorai, U.K.; Das, N.S.; Chattopadhyay, K.K.

    2016-01-01

    In this work, simple hydrothermal synthesis of water soluble Carbon quantum dots (CQDs) of different sizes has been reported. The effect of synthesis temperature and synthesis time on the particle size has also been shown. The structures of all the as-prepared samples were studied by field emission scanning electron microscope and high resolution transmission electron microscope. Fourier transformed infrared spectrophotometer analyzes the different bonding present in the sample whereas Raman spectrophotometer quantifies the hybridization state of the prepared samples. UV–vis spectrophotometer gives the variation of absorbance of all the samples with wavelength. Dynamic light scattering study shows the variation of particle size with deposition condition and corresponding zeta potential gives the idea about the stability of the CQD solutions. The photoluminescence (PL) properties of the as prepared CQDs were also studied in detail. It is noticed that with the increase of excitation wavelength, the PL emissions for the different samples were red shifted. The results have been explained in terms of the excitation dependent emission, variations in size of the CQD and presence of different functional groups on the surface of CQDs.

  2. Polarization-dependent photoluminescence studies of semipolar and nonpolar InGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Lukas; Schwarz, Ulrich [IAF, Freiburg (Germany); Wernicke, Tim; Weyers, Markus [FBH, Berlin (Germany); Kneissl, Michael [FBH, Berlin (Germany); Institute of Solid State Physics, TU Berlin (Germany)

    2010-07-01

    Light emitted from optical devices based on semi- and nonpolar GaN quantum well (QW) structures is partially or totally polarized, as a consequence of crystal symmetry and band structure. This can be an additional advantage over polar (0001)GaN in specific applications, e.g. in LED backlighting. Fundamentally, the polarized emission stems from breaking the isotropic symmetry of the hexagonal c-plane, resulting in two discrete semi- and nonpolar directions (parallel and normal to the projection of (0001)). We use the k.p method to simulate the crystal-direction dependent emission. The resulting transition matrix elements assign a specific (partial) polarization for each subband. The thermal occupation of the subbands results in a temperature dependent effective polarization of the light emission. We study MOVPE grown homoepitactical polar, semi- and nonpolar samples, measuring the polarization properties of the resonantly excited photoluminescence from the QW. With the complete polarization of the subbands for nonpolar devices it is possible to measure the energetic difference of the first two valence band levels. In contrast to our calculations we find a higher degree of polarization also in semipolar directions. A possible explanation could be a higher energetic subband difference than computed.

  3. Tuning the carbon nanotube photoluminescence enhancement at addition of cysteine through the change of external conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kurnosov, N.V.; Karachevtsev, M.V.; Leontiev, V.S.; Karachevtsev, V.A., E-mail: karachevtsev@ilt.kharkov.ua

    2017-01-15

    The enhancement of the photoluminescence (PL) from the semiconducting single-walled carbon nanotubes suspended with single-stranded DNA (ssDNA) in water observed after amino acids doping is the largest at cysteine addition. The PL intensity increased through the passivation of p-defects on the carbon nanotube sidewall by the cysteine molecules due to thiol group. The effect of several external factors on the cysteine-induced enhancement of PL from carbon nanotubes covered with ssDNA was studied: UV irradiation, tip or bath sonication treatment of the suspension, the ionic strength and pH of aqueous suspension. It turned out that all these factors have an essential influence on the dependence of the PL enhancement on the cysteine concentration through inducing of additional defects on nanotube as well as a change of the nanotube surface coverage with polymer. The obtained experimental results demonstrated that PL from carbon nanotubes can be exploited successfully for the monitoring of cysteine concentration in aqueous solution. - Highlights: • Cysteine doping enhances carbon nanotube emission more than other amino acids do. • SWNT emission dependence on cysteine concentration is tuned by UV irradiation and pH. • Type of sonication treatment influences SWNT PL dependence on cysteine concentration. • Polymer coverage and defectiveness of nanotubes effect on nanotube emission. • Graphic abstract.

  4. Photoluminescence of electron beam evaporated CaS:Bi thin films

    CERN Document Server

    Smet, P F; Poelman, D R; Meirhaeghe, R L V

    2003-01-01

    For the first time, the photoluminescence (PL) of electron beam evaporated CaS:Bi thin films is reported. Luminescent CaS:Bi powder prepared out of aqueous solutions was used as source material. The influence of substrate temperature on the PL and the morphology of thin films is discussed, and an optimum is determined. Substrate temperatures between 200 deg. C and 300 deg. C lead to good quality thin films with sufficient PL intensity. As-deposited thin films show two emission bands, peaking at 450 and 530 nm. Upon annealing the emission intensity increases, and annealing at 800 deg. C is sufficient to obtain a homogeneously blue emitting thin film (CIE colour coordinates (0.17; 0.12)), thanks to a single remaining emission band at 450 nm. The influence of ambient temperature on the PL of CaS:Bi powder and thin films was also investigated and it was found that CaS:Bi thin films show a favourable thermal quenching behaviour near room temperature.

  5. Photoluminescence study of Mn doped ZnS nanoparticles prepared by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, M. P., E-mail: vishwadeshpande@yahoo.co.in; Patel, Kamakshi, E-mail: kamphysics@gmail.com; Gujarati, Vivek P.; Chaki, S. H. [Department of Physics, Sardar Patel University, VallabhVidyanagr-388120,Anand, Gujarat, India. (India)

    2016-05-06

    ZnS nanoparticles co-doped with different concentration (5,10,15%) of Mn were synthesized using polyvinylpyrrolidone (PVP) as a capping agent under microwave irradiation. We confirmed doping of Mn in the host ZnS by EDAX whereas powder X-ray diffractogram showed the cubic zinc blende structure of all these samples. TEM images did showed agglomeration of particles and SAED pattern obtained indicated polycrystalline nature. From SAED pattern we calculated lattice parameter of the samples which have close resemblance from that obtained from XRD pattern. The band gap values of pure and doped ZnS nanoparticles were calculated from UV-Visible absorption spectra. ZnS itself is a luminescence material but when we dope it with transition metal ion such as Mn, Co, and Cu they exhibits strong and intense luminescence in the particular region. The photoluminescence spectra of pure ZnS nanoparticles showed an emission at 421 and 485nm which is blue emission which was originated from the defect sites of ZnS itself and also sulfur deficiency and when doped with Mn{sup 2+} an extra peak with high intensity was observed at 530nm which is nearly yellow-orange emission which isrelated to the presence of Mn in the host lattice.

  6. Fabrication and micro-photoluminescence property of CdSe/CdS core/shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Guozhang; Gou, Guangyang; Wu, Zeming; Chen, Yu; Li, Hongjian [Central South University, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Changsha, Hunan (China); Wan, Qiang [Hunan University, School of Physics and Electronics, Changsha (China); Zou, Bingsuo [Beijing Institute of Technology, Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing (China)

    2015-04-01

    Hetero-epitaxial CdSe/CdS core/shell nanowires (NWs) were prepared by a source-controllable chemical vapor deposition method. A two-stage growth mechanism was proposed to the growth process of the core/shell NWs. Micro-photoluminescence (μ-PL) property of individual NW was studied by a confocal microscopy system. The pure CdSe NW emits a red light with peak at 712.3 nm, which is inconsistent with the CdSe band-edge emission. The CdSe/CdS core/shell NW emits two apparent peaks, one is an intensive red emission peak centered at 715.2 nm and the other is a weak green emission peak located at 516.2 nm. The room temperature μ-PL spectrum shows that the PL intensity of CdSe NW was evidently promoted by coating the CdS shell, and this is because CdS improves the surface state optimizing the energy band structure of CdSe NW. The as-synthesized CdSe/CdS core/shell NW has more efficient PL quantum yields than pure CdSe NW and may find potential applications in nanoscale photonic devices. (orig.)

  7. Fabrication and micro-photoluminescence property of CdSe/CdS core/shell nanowires

    International Nuclear Information System (INIS)

    Dai, Guozhang; Gou, Guangyang; Wu, Zeming; Chen, Yu; Li, Hongjian; Wan, Qiang; Zou, Bingsuo

    2015-01-01

    Hetero-epitaxial CdSe/CdS core/shell nanowires (NWs) were prepared by a source-controllable chemical vapor deposition method. A two-stage growth mechanism was proposed to the growth process of the core/shell NWs. Micro-photoluminescence (μ-PL) property of individual NW was studied by a confocal microscopy system. The pure CdSe NW emits a red light with peak at 712.3 nm, which is inconsistent with the CdSe band-edge emission. The CdSe/CdS core/shell NW emits two apparent peaks, one is an intensive red emission peak centered at 715.2 nm and the other is a weak green emission peak located at 516.2 nm. The room temperature μ-PL spectrum shows that the PL intensity of CdSe NW was evidently promoted by coating the CdS shell, and this is because CdS improves the surface state optimizing the energy band structure of CdSe NW. The as-synthesized CdSe/CdS core/shell NW has more efficient PL quantum yields than pure CdSe NW and may find potential applications in nanoscale photonic devices. (orig.)

  8. Photoluminescence varied by selective excitation in BiGdWO6:Eu3+ phosphor

    Science.gov (United States)

    Pavani, K.; Graça, M. P. F.; Kumar, J. Suresh; Neves, A. J.

    2017-12-01

    Eu3+ doped bismuth gadolinium tungstate (BGW), a simplest member of Aurivillius family of layered perovskites, was synthesized by solid-state reaction method. Structural characterisation has been performed by X-Ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Band gap of the host matrix has been calculated using reflectance and absorption spectra. Three different mechanisms were found to explain the excitation of Eu3+ ions and are described in detail. Photoluminescence (PL) spectra of the BGW phosphor doped with Eu3+ ions consist of major emission lines associated with 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) of Eu3+ ion. Site selective PL excitation and emission indicates that Eu3+ ions doped in BiGdWO6 are sensitive to the excitation wavelength without change in the structure. Change in emission spectra were observed when the excitation wavelength was changed. Judd-Ofelt (J-O) parameters were determined from the indirect method to interpret the interactions between the host and dopant ions along with detailed analysis of lifetime measurements.

  9. Structure and photoluminescence properties of ZnS films grown on porous Si substrates

    Science.gov (United States)

    Wang, Cai-feng; Hu, Bo; Yi, Hou-hui; Li, Wei-bing

    2011-11-01

    ZnS films were deposited on porous silicon (PS) substrates with different porosities. With the increase of PS substrate porosity, the XRD diffraction peak intensity decreases and the surface morphology of the ZnS films becomes rougher. Voids appear in the films, due to the increased roughness of PS structure. The photoluminescence (PL) spectra of the samples before and after deposition of ZnS were measured to study the effect of substrate porosity on the luminescence properties of ZnS/PS composites. As-prepared PS substrates emit strong red light. The red PL peak of PS after deposition of ZnS shows an obvious blueshift. As PS substrate porosity increases, the trend of blueshift increases. A green emission at about 550 nm was also observed when the porosity of PS increased, which is ascribed to the defect-center luminescence of ZnS. The effect of annealing time on the structural and luminescence properties of ZnS/PS composites were also studied. With the increase of annealing time, the XRD diffraction peak intensity and the self-activated luminescence intensity of ZnS increase, and, the surface morphology of the ZnS films becomes smooth and compact. However, the red emission intensity of PS decreases, which was associated with a redshift. White light emission was obtained by combining the luminescence of ZnS with the luminescence of PS.

  10. Humidity-Induced Photoluminescence Hysteresis in Variable Cs/Br Ratio Hybrid Perovskites.

    Science.gov (United States)

    Howard, John M; Tennyson, Elizabeth M; Barik, Sabyasachi; Szostak, Rodrigo; Waks, Edo; Toney, Michael F; Nogueira, Ana F; Neves, Bernardo R A; Leite, Marina S

    2018-06-12

    Hybrid organic-inorganic perovskites containing Cs are a promising new material for light-absorbing and light-emitting optoelectronics. However, the impact of environmental conditions on their optical properties is not fully understood. Here, we elucidate and quantify the influence of distinct humidity levels on the charge carrier recombination in Cs x FA 1- x Pb(I y Br 1- y ) 3 perovskites. Using in situ environmental photoluminescence (PL), we temporally and spectrally resolve light emission within a loop of critical relative humidity (rH) levels. Our measurements show that exposure up to 35% rH increases the PL emission for all Cs (10-17%) and Br (17-38%) concentrations investigated here. Spectrally, samples with larger Br concentrations exhibit PL redshift at higher humidity levels, revealing water-driven halide segregation. The compositions considered present hysteresis in their PL intensity upon returning to a low-moisture environment due to partially reversible hydration of the perovskites. Our findings demonstrate that the Cs/Br ratio strongly influences both the spectral stability and extent of light emission hysteresis. We expect our method to become standard when testing the stability of emerging perovskites, including lead-free options, and to be combined with other parameters known for affecting material degradation, e.g., oxygen and temperature.

  11. Photoluminescence of patterned CdSe quantum dot for anti-counterfeiting label on paper

    International Nuclear Information System (INIS)

    Isnaeni,; Yulianto, Nursidik; Suliyanti, Maria Margaretha

    2016-01-01

    We successfully developed a method utilizing colloidal CdSe nanocrystalline quantum dot for anti-counterfeiting label on a piece of glossy paper. We deposited numbers and lines patterns of toluene soluble CdSe quantum dot using rubber stamper on a glossy paper. The width of line pattern was about 1-2 mm with 1-2 mm separation between lines. It required less than one minute for deposited CdSe quantum dot on glossy paper to dry and become invisible by naked eyes. However, patterned quantum dot become visible using long-pass filter glasses upon excitation of UV lamp or blue laser. We characterized photoluminescence of line patterns of quantum dot, and we found that emission boundaries of line patterns were clearly observed. The error of line size and shape were mainly due to defect of the original stamper. The emission peak wavelength of CdSe quantum dot was 629 nm. The emission spectrum of deposited quantum dot has full width at half maximum (FWHM) of 30-40 nm. The spectra similarity between deposited quantum dot and the original quantum dot in solution proved that our stamping method can be simply applied on glossy paper without changing basic optical property of the quantum dot. Further development of this technique is potential for anti-counterfeiting label on very important documents or objects.

  12. Probing defects in ZnO nanostructures by Photoluminescence and Positron Annihilation Spectroscopy

    Science.gov (United States)

    Ghosh, Manoranjan; Raychaudhuri, A. K.; Chaudhuri, S. K.; Das, Dipankar

    2008-03-01

    We have investigated defect related emission in the blue green region (2.2 eV -- 2.5 eV) of ZnO nanostructures having spherical (5 nm-15 nm) as well as those with hexagonal platelet and rod like morphologies (20nm-100 nm), synthesized by solvo-thermal route. This emission show anomalous size dependence. Emission energy near 2.2 eV, shifts to higher energy (2.5 eV) for increase in size beyond 20nm when shape of the nanostructures changes. This change in photoluminescence has a close correlation with the size (and shape) induced change in the positron trapping rate which is directly proportional to the defect concentration. The trapping rates show non-monotonous dependence on size. It increases initially as the size increases (5nm-15nm) and then decreases as the size increases beyond 20nm. While increase of the trapping rate on size reduction is expected due to accumulation of more defects at the surface, the initial dependence of the trapping rate on the size (below 20nm) is anomalous. The data are explained by the presence of defects like Zn vacancy and confinement due to size reduction.

  13. Room temperature photoluminescence properties of ZnO nanorods grown by hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Iwan, S., E-mail: iwan-sugihartono@unj.ac.id [Jurusan Fisika, FMIPA-UNJ, Rawamangun, Jakarta (Indonesia); Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Fauzia, Vivi [Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Umar, A. A. [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor (Malaysia); Sun, X. W. [School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue (Singapore)

    2016-04-19

    Zinc oxide (ZnO) nanorods were fabricated by a hydrothermal reaction on silicon (Si) substrate at 95 °C for 6 hours. The ZnO seed layer was fabricated by depositing ZnO thin films on Si substrates by ultrasonic spray pyrolisis (USP). The annealing effects on crystal structure and optical properties of ZnO nanorods were investigated. The post-annealing treatment was performed at 800 °C with different environments. The annealed of ZnO nanorods were characterized by X-ray diffraction (XRD) and photoluminescence (PL) in order to analyze crystal structure and optical properties, respectively. The results show the orientations of [002], [101], [102], and [103] diffraction peaks were observed and hexagonal wurtzite structure of ZnO nanorods were vertically grown on Si substrates. The room temperature PL spectra show ultra-violet (UV) and visible emissions. The annealed of ZnO nanorods in vacuum condition (3.8 × 10{sup −3} Torr) has dominant UV emission. Meanwhile, non-annealed of ZnO nanorods has dominant visible emission. It was expected that the annealed of ZnO in vacuum condition suppresses the existence of native defects in ZnO nanorods.

  14. Photoluminescence properties of Er{sup 3+}-doped alkaline earth titanium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, D.V.R.; Babu, A. Mohan [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jamalaiah, B.C. [Department of Physics, Sree Vidyanikethan Engineering College, Tirupati, 517 102 (India); Moorthy, L. Rama, E-mail: lrmphysics@yahoo.co.i [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jayasimhadri, M.; Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung Soo [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)

    2010-02-18

    Er{sup 3+}-doped alkaline earth titanium phosphate (RTP) glasses with molar composition of 24 (NaPO{sub 3}){sub 6} + 30 KH{sub 2}PO{sub 4} + 25 TiO{sub 2} + 20 RCl{sub 2} + 1 Er{sub 2}O{sub 3} were prepared by melt quenching technique. Judd-Ofelt intensity parameters ({Omega}{sub 2,4,6}) were determined from the experimental oscillator strengths (f{sub exp}) of absorption bands. From these parameters spontaneous emission probabilities (A{sub R}), luminescence branching ratios ({beta}{sub R}) and radiative lifetimes ({tau}{sub R}) have been calculated. Visible and near infrared photoluminescence spectra has been recorded by exciting the samples at 380 and 970 nm respectively. An intense broad emission band at 1.53 {mu}m was observed corresponding to {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition. McCumber theory has been applied to determine the emission cross-sections ({sigma}{sub e}) of the {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition using the absorption cross-sections ({sigma}{sub a}). The lifetimes of {sup 4}S{sub 3/2} level were measured for the glasses by exciting the samples at 540 nm wavelength and the quantum efficiencies were also determined.

  15. Photoluminescence study of Dy3+ doped SrCeVO5 phosphor

    International Nuclear Information System (INIS)

    Suresh, K.; Dai, Ch. Vijay Anil; Murthy, K.V.R.

    2016-01-01

    Dy 3+ doped SrCeVO 5 phosphor was synthesized by the solid-state reaction method. Photoluminescence (PL) technique was performed to characterize the sample. The excitation spectra monitored under 520 nm and 610 nm wavelength was characterized by a broad band ranging from 220-400 nm. From the excitation spectra two main bands at 265 nm and 325 nm were observed. The PLE intensity of 520 nm monitored shows high intensity than 610 nm spectrum. The emission spectra of SrCeVO 5 phosphor under excitations at 265 nm and 325 nm exhibited main peak at 515 nm (cyan) which is a strong, intense well resolved peak with FWHM (full width at half maximum) of 130 nm is observed. This emission is mainly may be due to Ce ion but not Dy ion. The same emission under 640 and 670 nm excitations (up conversion) with good intensity was also observed. Commission international de l'eclairage (CIE) co-ordinates under these excitations revealed that this phosphor emit cyan colour and could be used for the generation of white light in display and lamp devices. (author)

  16. Photoluminescence of patterned CdSe quantum dot for anti-counterfeiting label on paper

    Energy Technology Data Exchange (ETDEWEB)

    Isnaeni,, E-mail: isnaeni@lipi.go.id; Yulianto, Nursidik; Suliyanti, Maria Margaretha [Research Center for Physics, Indonesian Institute of Sciences, Building 442, Kawasan Puspiptek, South Tangerang,Banten 15314 Indonesia (Indonesia)

    2016-03-11

    We successfully developed a method utilizing colloidal CdSe nanocrystalline quantum dot for anti-counterfeiting label on a piece of glossy paper. We deposited numbers and lines patterns of toluene soluble CdSe quantum dot using rubber stamper on a glossy paper. The width of line pattern was about 1-2 mm with 1-2 mm separation between lines. It required less than one minute for deposited CdSe quantum dot on glossy paper to dry and become invisible by naked eyes. However, patterned quantum dot become visible using long-pass filter glasses upon excitation of UV lamp or blue laser. We characterized photoluminescence of line patterns of quantum dot, and we found that emission boundaries of line patterns were clearly observed. The error of line size and shape were mainly due to defect of the original stamper. The emission peak wavelength of CdSe quantum dot was 629 nm. The emission spectrum of deposited quantum dot has full width at half maximum (FWHM) of 30-40 nm. The spectra similarity between deposited quantum dot and the original quantum dot in solution proved that our stamping method can be simply applied on glossy paper without changing basic optical property of the quantum dot. Further development of this technique is potential for anti-counterfeiting label on very important documents or objects.

  17. Detection of CdSe quantum dot photoluminescence for security label on paper

    Energy Technology Data Exchange (ETDEWEB)

    Isnaeni,, E-mail: isnaeni@lipi.go.id; Sugiarto, Iyon Titok [Research Center for Physics, Indonesian Institute of Science, Building 442 Puspiptek Serpong, South Tangerang, Banten, Indonesia 15314 (Indonesia); Bilqis, Ratu; Suseno, Jatmiko Endro [Department of Physics, Diponegoro University, Jl. Prof. Soedarto, Tembalang, Semarang, Indonesia 50275 (Indonesia)

    2016-02-08

    CdSe quantum dot has great potential in various applications especially for emitting devices. One example potential application of CdSe quantum dot is security label for anti-counterfeiting. In this work, we present a practical approach of security label on paper using one and two colors of colloidal CdSe quantum dot, which is used as stamping ink on various types of paper. Under ambient condition, quantum dot is almost invisible. The quantum dot security label can be revealed by detecting emission of quantum dot using photoluminescence and cnc machine. The recorded quantum dot emission intensity is then analyzed using home-made program to reveal quantum dot pattern stamp having the word ’RAHASIA’. We found that security label using quantum dot works well on several types of paper. The quantum dot patterns can survive several days and further treatment is required to protect the quantum dot. Oxidation of quantum dot that occurred during this experiment reduced the emission intensity of quantum dot patterns.

  18. Spin-Related Micro-Photoluminescence in Fe3+ Doped ZnSe Nanoribbons

    Directory of Open Access Journals (Sweden)

    Lipeng Hou

    2016-12-01

    Full Text Available Spin-related emission properties have important applications in the future information technology; however, they involve microscopic ferromagnetic coupling, antiferromagnetic or ferrimagnetic coupling between transition metal ions and excitons, or d state coupling with phonons is not well understood in these diluted magnetic semiconductors (DMS. Fe3+ doped ZnSe nanoribbons, as a DMS example, have been successfully prepared by a thermal evaporation method. Their power-dependent micro-photoluminescence (PL spectra and temperature-dependent PL spectra of a single ZnSe:Fe nanoribbon have been obtained and demonstrated that alio-valence ion doping diminishes the exciton magnetic polaron (EMP effect by introducing exceeded charges. The d-d transition emission peaks of Fe3+ assigned to the 4T2 (G → 6A1 (S transition at 553 nm and 4T1 (G → 6A1 (S transition at 630 nm in the ZnSe lattice have been observed. The emission lifetimes and their temperature dependences have been obtained, which reflected different spin–phonon interactions. There exists a sharp decrease of PL lifetime at about 60 K, which hints at a magnetic phase transition. These spin–spin and spin–phonon interaction related PL phenomena are applicable in the future spin-related photonic nanodevices.

  19. Photoluminescence study of epitaxially grown ZnSnAs2:Mn thin films

    International Nuclear Information System (INIS)

    Mammadov, E; Haneta, M; Toyota, H; Uchitomi, N

    2011-01-01

    The photoluminescence (PL) properties of heavily Mn-doped ZnSnAs 2 layers epitaxially grown on nearly lattice-matched semi-insulating InP substrates are studied. PL spectra are obtained for samples with Mn concentrations of 5, 12 and 24 mol% relative to the combined concentrations of Zn and Sn. A broad emission band centered at ∼ 1 eV is detected for Mn-doped layers at room temperature. The emission is a intense broad asymmetric line at low temperatures. The line is reconstructed by superposition of two bands with peak energies of ∼ 0.99 and 1.07 eV, similar to those reported for InP. These bands are superimposed onto a 1.14 eV band with well-resolved phonon structure for the layer doped with 12 % Mn. Recombination mechanism involving the split-off band of the ZnSnAs 2 is suggested. Temperature dependence of integrated intensities of the PL bands indicates to thermally activated emission with activation energies somewhat different from those found for InP. Mn substitution at cationic sites increases the concentration of holes which may act as recombination centers. Recombination to the holes bound to Mn ions with the ground state located below the top of the valence band has been proposed as a possible PL mechanism.

  20. Chemical sensitivity of InP/In0.48Ga0.52P surface quantum dots studied by time-resolved photoluminescence spectroscopy

    International Nuclear Information System (INIS)

    De Angelis, Roberta; Casalboni, Mauro; De Matteis, Fabio; Hatami, Fariba; Masselink, William T.; Zhang, Hong; Prosposito, Paolo

    2015-01-01

    InP/InGaP surface quantum dots represent an attractive material for optical chemical sensors since they show a remarkable near infra-red emission at room temperature, whose intensity increases rapidly and reversibly depending on the composition of the environmental atmosphere. We show here their emission properties by time resolved photoluminescence spectroscopy investigation. Photoluminescence transients with and without chemical solvent vapours (methanol, clorophorm, acetone and water) were fitted with a 3-exponential decay law with times of about 0.5 ns, 2 ns and 7 ns. The measurements revealed a weak effect on clorophorm, acetone and water, while the initial decay time of InP surface quantum dots increases (up to 15%) upon methanol vapour exposure, indicating that the organic molecules efficiently saturate QD non-radiative surface states. - Highlights: • InP SQDs emission depends on the presence of solvent vapours in the atmosphere. • TR photoluminescence transients were fitted with a 3-exponential decay law. • The initial decay time increases (up to 15%) upon methanol vapour exposure. • Organic molecules efficiently saturate QD non-radiative surface states.

  1. Field-induced spin splitting and anomalous photoluminescence circular polarization in C H3N H3Pb I3 films at high magnetic field

    Science.gov (United States)

    Zhang, Chuang; Sun, Dali; Yu, Zhi-Gang; Sheng, Chuan-Xiang; McGill, Stephen; Semenov, Dmitry; Vardeny, Zeev Valy

    2018-04-01

    The organic-inorganic hybrid perovskites show excellent optical and electrical properties for photovoltaic and a myriad of other optoelectronics applications. Using high-field magneto-optical measurements up to 17.5 T at cryogenic temperatures, we have studied the spin-dependent optical transitions in the prototype C H3N H3Pb I3 , which are manifested in the field-induced circularly polarized photoluminescence emission. The energy splitting between left and right circularly polarized emission bands is measured to be ˜1.5 meV at 17.5 T, from which we obtained an exciton effective g factor of ˜1.32. Also from the photoluminescence diamagnetic shift we estimate the exciton binding energy to be ˜17 meV at low temperature. Surprisingly, the corresponding field-induced circular polarization is "anomalous" in that the photoluminescence emission of the higher split energy band is stronger than that of the lower split band. This "reversed" intensity ratio originates from the combination of long electron spin relaxation time and hole negative g factor in C H3N H3Pb I3 , which are in agreement with a model based on the k.p effective-mass approximation.

  2. Violet-blue photoluminescence from Si nanoparticles with zinc-blende structure synthesized by laser ablation in liquids

    Directory of Open Access Journals (Sweden)

    P. Liu

    2013-02-01

    Full Text Available Violet-blue luminescence from Si nanostructures has been widely investigated, because of its potential use in optoelectronic and bioimaging devices. However, the emission mechanism in multiform Si nanomaterials remains unclear. In this contribution, Si nanocrystals (NCs with zincblende structure and visible violet-blue emission are prepared by electric field assisted laser ablation in liquids. While subsequent annealing of the Si NCs weakens their blue emission dramatically. We investigate the origin of the violet-blue emission by monitoring crystal structure transitions and photoluminescence during different treatments of the Si NCs. The results indicate that the violet-blue emission cannot simply be ascribed to quantum confinement effects or the presence of general surface states on the Si NCs. Instead, we propose that excitons are formed within the Si NCs by direct transitions at Γ or X points, which can be induced during the formation of the zincblende structure, and are a most possible origin of the violet-blue luminescence. Furthermore, defects in the metastable Si NCs are also expected to play an important role in violet-blue emission. This study not only gives clear and general insight into the physical origins of violet-blue emission from Si NCs, it also provides useful information for designing optoelectronic devices based on Si NCs.

  3. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  4. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    International Nuclear Information System (INIS)

    Chen, S J; Liu, Y C; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn 3 P 2 . Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I 4 ) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrates

  5. A novel photoluminescent and photochromic europium complex

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A ternary europium complex of 4-aminobutyric acid (ABA) with 1,10-phenanthroline (phen) [Eu2(ABA)4 (phen)4](phen)4(ClO4)6 was synthesized and characterized by X-ray single crystal diffraction. The result shows that 4-aminobutyric acid exists in zwitterion form in the binuclear complex and that the carboxylates coordinate with Eu3+ ion in bidentate bridging and tridentate chelating-bridging modes. There are two types of phen molecules, one is coordinated and the other is uncoordinated. When excited by YAG: Nd laser with 355 nm light, the title complex can emit strong red fluorescence, and its high-resolution emission spectrum was recorded at 77 K. The Eu3+ ion site is in low symmetry, which is in agreement with the result of X-ray single crystal diffraction analysis. When irradiated with a mercury lamp, the aqueous solution of the title complex can perform photochromism with the color change from colorless to green and the green color can fade away in the dark. The photochromic response time is related to the concentration and pH of the solution, the temperature and the light intensity.

  6. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  7. Investigation of the photoluminescence properties of Au/ZnO/sapphire and ZnO/Au/sapphire films by experimental study and electromagnetic simulation

    International Nuclear Information System (INIS)

    Zeng, Yong; Zhao, Yan; Jiang, Yijian

    2015-01-01

    Highlights: • Photoluminescent properties from Au/ZnO/sapphire and ZnO/Au/sapphire structures have been investigated. • The enhancement of UV intensity is a result of the enhanced electric field intensity of the 325 nm excitation light. • Electron transfer which induced by the local surface may be also account for the enhancement of UV emissions. • The suppression of the visible emissions might be due to the flowing of electrons in the defect states to the Au. - Abstract: Photoluminescent properties from Au/ZnO/sapphire and ZnO/Au/sapphire structures have been investigated. It is found that due to the co-interaction between the incident light and local surface plasmons, the ultraviolet (UV) emissions from the two structures were both enhanced and the visible emissions related to the defects were suppressed. By the means of electromagnetic simulation, it indicates that the enhancement of UV intensity is a result of the enhanced electric field intensity of the 325 nm excitation light, which is induced by localized surface plasmons resonance (LSPR). On the other hand, electron transfer which is induced by the local surface also account for the enhancement of UV emissions. The suppression of the visible emissions might be due to the flowing of electrons in the defect states to the Au, which caused the reduction of the electrons in the defect states

  8. Effects of stabilizer ratio on photoluminescence properties of sol-gel ZnO nano-structured thin films

    International Nuclear Information System (INIS)

    Boudjouan, F.; Chelouche, A.; Touam, T.; Djouadi, D.; Khodja, S.; Tazerout, M.; Ouerdane, Y.; Hadjoub, Z.

    2015-01-01

    Nanostructured ZnO thin films with different molar ratios of MEA to zinc acetate (0.5, 1.0, 1.5 and 2.0) have been deposited on glass substrates by a sol–gel dip coating technique. X-ray diffraction, Scanning Electron Microscopy, UV–visible spectrophotometry and photoluminescence spectroscopy have been employed to investigate the effect of MEA stabilizer ratio on structural, morphological, absorbance and emission properties of the ZnO thin films. Diffraction patterns have shown that all the films are polycrystalline and exhibit a wurtzite hexagonal structure. The c axis orientation has been enhanced with increasing stabilizer ratio. SEM micrographs have revealed that the morphology of the ZnO films depend on stabilizer ratio. The UV–visible absorption spectra have demonstrated that the optical absorption is affected by stabilizer ratio. The photoluminescence spectra have indicated one ultraviolet and two visible emission bands (green and red), while band intensities are found to be dependent on stabilizer ratio. ZnO thin films deposited at MEA ratio of 1.0 show the highest UV emission while the minimum UV emission intensity is observed in thin films deposited at ratio of 0.5 and the maximum green has been recorded for films deposited at MEA ratio of 2.0. - Highlight: • c axis orientation increases with increasing MEA ratio. • The increase of MEA ration from 0.5 to 1.0 enhances greatly the UV emission. • The larger I UV /I visible is obtained for the MEA to Zn ratio of 1:1. • The MEA ratio of 0.5 favors the formation of large density of V zn . • The MEA ratio of 2.0 increases the V o density

  9. UV-VIS and photoluminescence spectroscopy for nanomaterials characterization

    CERN Document Server

    2013-01-01

    Second volume of a 40-volume series on nanoscience and nanotechnology, edited by the renowned scientist Challa S.S.R. Kumar. This handbook gives a comprehensive overview about UV-visible and photoluminescence spectroscopy for the characterization of nanomaterials. Modern applications and state-of-the-art techniques are covered and make this volume essential reading for research scientists in academia and industry in the related fields.

  10. Photoluminescent polysaccharide-coated germanium(IV) oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Lobaz, Volodymyr; Rabyk, Mariia; Pánek, Jiří; Doris, E.; Nallet, F.; Štěpánek, Petr; Hrubý, Martin

    2016-01-01

    Roč. 294, č. 7 (2016), s. 1225-1235 ISSN 0303-402X R&D Projects: GA MŠk(CZ) 7AMB14FR027; GA ČR(CZ) GA13-08336S; GA MZd(CZ) NV15-25781A Institutional support: RVO:61389013 Keywords : germanium oxide nanoparticles * polysaccharide coating * photoluminescent label Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.723, year: 2016

  11. Power-law photoluminescence decay in quantum dots

    Czech Academy of Sciences Publication Activity Database

    Král, Karel; Menšík, Miroslav

    2013-01-01

    Roč. 5, č. 6 (2013), s. 608-610 ISSN 2164-6627 R&D Projects: GA MŠk(CZ) OC10007; GA MŠk LH12236; GA MŠk LH12186 Institutional support: RVO:68378271 ; RVO:61389013 Keywords : quantum dots * indirect gap * photoluminescence * electron-phonon interaction * non-adiabatic Subject RIV: BM - Solid Matter Physics ; Magnetism; JA - Electronics ; Optoelectronics, Electrical Engineering (UMCH-V)

  12. Photoluminescence of monovalent indium centres in phosphate glass

    OpenAIRE

    Masai, Hirokazu; Yamada, Yasuhiro; Okumura, Shun; Yanagida, Takayuki; Fujimoto, Yutaka; Kanemitsu, Yoshihiko; Ina, Toshiaki

    2015-01-01

    Valence control of polyvalent cations is important for functionalization of various kinds of materials. Indium oxides have been used in various applications, such as indium tin oxide in transparent electrical conduction films. However, although metastable In+ (5 s2 configuration) species exhibit photoluminescence (PL), they have attracted little attention. Valence control of In+ cations in these materials will be important for further functionalization. Here, we describe In+ species using PL ...

  13. Study on the fabrication and photoluminescence characteristics of LiPO3 glass scintillators with the lanthanides activators

    International Nuclear Information System (INIS)

    Jeong, S. Z.; Lee, J. M.; Hwang, J. H.; Choi, S. H.

    2001-01-01

    In this syudy, LiPO 3 glass scintillators were fabricated, and lanthanides (except Pm) oxides or chlorides were used as an activator. For the fabrication of LiPO 3 glasses, optimum heating conditions were obtained, and the photoluminescence of the glasses was measured by the monochromator. For the best transparency of the glass samples, optimum heating temperature and time is 950 .deg. C and 90 min, respectively. As the result of photoluminescence analysis, it was impossible to apply Pr, Nd, Gd, Ho, Er, Tm, Yb, and Lu to activator. Because emission spectrum of samples with them was equal to that of sample without activator. In case of samples with Europium, the peak of emission spectrum of Eu(II) and Eu(III) is 420 nm and 620 nm, separately. And Samples with Ce(III) are about 380 nm, and Tb(III) are about 550 nm. On the fabrication of LiPO 3 glass samples, PL intensity was increased by adding sugar as reductant, and using Ar reduction atmosphere. And the optimum reduction conditions were differed as to the kinds of activators. Samples with Eu(II) and Tb(III) have the best PL intensity in the Ar reduction atmosphere, and sample with Ce(III) have the best intensity by added sugar

  14. Study on the fabrication and photoluminescence characteristics of LiBO2 glass scintillators with the lanthanides activators

    International Nuclear Information System (INIS)

    Sin, S. W.; Hwang, J. H.; Choi, S. H.; Sumarokov, S. Yu.

    2002-01-01

    LiBO 2 glass scintillators were fabricated, and lanthanides(except Pm) oxides or chlorides were used as an activator. For the fabrication of LiBO 2 glasses, optimum heating conditions were obtained, and the photoluminescence of the glasses was measured by the monochromator. For the best transparency of the glass samples, optimum heating temperature and time are 1000 .deg. C and 40 min, respectively. The result of photoluminescence analysis shows that Pr, Nd, Gd, Ho, Er, Tm, Yb, and Lu are not good as activator. Because emission spectrum of samples with them was equal to that of sample without activator. In the case of samples with Europium, the peak of emission spectrum of Eu(III) is 810 nm. And Samples with Ce(III) are 760 nm, and Tb(III) are about 535 nm. Samples with Ce(III) and Tb(III) have the best PL intensity with added sugar in Ar reduction atmosphere, and sample with Eu(III) has the best intensity without a reducing process

  15. Synthesis, Photoluminescence Behavior of Green Light Emitting Tb(III) Complexes and Mechanistic Investigation of Energy Transfer Process.

    Science.gov (United States)

    Bala, Manju; Kumar, Satish; Devi, Rekha; Khatkar, Avni; Taxak, V B; Boora, Priti; Khatkar, S P

    2018-06-04

    A series of five new terbium(III) ion complexes with 4,4-difluoro-1-phenylbutane-1,3-dione (HDPBD) and anciliary ligands was synthesized. The composition and properties of complexes were analyzed by elemental analysis, IR, NMR, powder X-ray diffaraction, TG-DTG and photoluminescence spectroscopy. These complexes exhibited ligand sensitized green emission at 546 nm associated with 5 D 4  →  7 F 5 transitions of terbium ion in the emission spectra. The photoluminescence study manifested that the organic ligands act as antenna and facilitate the absorbed energy to emitting levels of Tb(III) ion efficiently. The enhanced luminescence intensity and decay time of ternary C2-C5 complexes observed due to synergistic effect of anciliary ligands. The CIE color coordinates of complexes came under the green region of chromaticity diagram. The mechanistic investigation of intramolecular energy transfer in the complexes was discussed in detail. These terbium(III) complexes can be thrivingly used as one of the green component in light emitting material and in display devices. Graphical Abstract Illustrate the sensitization process of the Tb ion and intramolecular energy transfer process in the Tb 3+ complex.

  16. Nanomaterial Host Bands Effect on the Photoluminescence Properties of Ce-Doped YAG Nanophosphor Synthesized by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    L. Guerbous

    2015-01-01

    Full Text Available Cerium trivalent (Ce3+ doped YAG nano-sized phosphors have been successfully synthesized by sol-gel method using different annealing temperatures. The samples have been characterized by X-ray diffraction (XRD, thermogravimetry (TG, differential scanning calorimetry (DSC analysis, Fourier transform infrared (FTIR spectroscopy, and steady photoluminescence (PL spectroscopy. X-ray diffraction analysis indicates that the pure cubic phase YAG was formed and strongly depends on the cerium content and the annealing temperature. It was found that the grain size ranges from 30 to 58 nm depending on the calcination temperature. The YAG: Ce nanophosphors showed intense, green-yellow emission, corresponding to Ce3+ 5d1→2F5/2, 2F7/2 transitions and its photoluminescence excitation spectrum contains the two Ce3+ 4f1→5d1, 5d2 bands. The crystal filed splitting energy levels positions 5d1 and 5d2 and the emission transitions blue shift with annealing temperatures have been discussed. It was found that the Ce3+ 4f1 ground state position relative to valence band maximum of YAG host nanomaterial decreases with increasing the temperature.

  17. Stimulated emission (4F3/2 → 4I11/2 channel) with LD and Xe-flashlamp pumping of tetragonal, incommensurately modulated Ca2MgSi2O7:Nd3+(Na+) – a new disordered laser crystal

    International Nuclear Information System (INIS)

    Kaminskii, A A; Nakao, H; Ueda, K; Shirakawa, A; Bohatý, L; Becker, P; Liebertz, J; Kleinschrodt, R

    2010-01-01

    Non-centrosymmetric tetragonal crystal Ca 2 MgSi 2 O 7 :Nd 3+ (Na + ) with incommensurately modulated melilite-type structure is presented as a new laser crystal. By LD and Xe-flashlamp pumping its CW and free-running pulsed stimulated emission of the 4 F 3/2 → 4 I 11/2 generation channel of Nd 3+ lasant ions was excited

  18. Single-crystalline spherical β-Ga2O3 particles: Synthesis, N-doping and photoluminescence properties

    International Nuclear Information System (INIS)

    Zhang, Tingting; Lin, Jing; Zhang, Xinghua; Huang, Yang; Xu, Xuewen; Xue, Yanming; Zou, Jin; Tang, Chengchun

    2013-01-01

    We report on the synthesis of single-crystalline spherical β-Ga 2 O 3 particles by a simple method in ambient atmosphere. No pre-treatment, catalyst, substrate, or gas flow was required during the synthesis process. The well-dispersed Ga 2 O 3 particles display uniform spherical morphology with an average diameter of ∼200 nm. Photoluminescence studies indicate that the Ga 2 O 3 particles exhibit a broad blue-green light emission and an interesting red light emission at room temperature. The red light emission can be further tuned by post-annealing of the particles in ammonia atmosphere. The present single-crystalline β-Ga 2 O 3 particles with spherical morphology, uniform sub-micrometer sizes and tunable light emission are envisaged to be of high promise for applications in white-LED phosphors and optoelectronic devices. -- Highlights: ► We prepared single-crystalline spherical β-Ga 2 O 3 particles in ambient atmosphere. ► The particles display uniform spherical morphology with an average diameter of ∼200 nm. ► The Ga 2 O 3 particles exhibit a broad blue-green light and an interesting red light emission. ► The red light emission can be further tuned by post-annealing of the particles

  19. Photoluminescence studies of a Terbium(III) complex as a fluorescent probe for DNA detection

    Energy Technology Data Exchange (ETDEWEB)

    Khorasani-Motlagh, Mozhgan, E-mail: mkhorasani@chem.usb.ac.ir; Noroozifar, Meissam; Niroomand, Sona; Moodi, Asieh

    2013-11-15

    The photoluminescence properties of a Tb(III) complex of the form [Tb(phen){sub 2}Cl{sub 3}·OH{sub 2}] (phen=1,10-phenanthroline) in different solvents are presented. It shows the characteristic luminescence of the corresponding Ln{sup 3+} ion in the visible region. The emission intensity of this complex in coordinating solvent is higher than non-coordinating one. The suggested mechanism for the energy transfer between the ligand and Tb{sup 3+} ion is the intramolecular energy transfer mechanism. The interactions of the Tb(III) complex with fish salmon DNA are studied by fluorescence spectroscopy, circular dichroism study and viscosity measurements. The results of fluorescence titration reveal that DNA strongly quenches the intrinsic fluorescence of the complex through a static quenching procedure. The binding constant (K{sub b}) of the above metal complex at 25 °C is determined by the fluorescence titration method and it is found to be (8.06±0.01)×10{sup 3} M{sup −1}. The thermodynamic parameters (ΔH{sup 0}>0, ΔS{sup 0}>0 and ΔG{sup 0}<0) indicate that the hydrophobic interactions play a major role in DNA–Tb complex association. The results support the claim that the title complex bonds to FS-DNA by a groove mode. -- Highlights: • Photoluminescence of [Tb(phen){sub 2}Cl{sub 3}·OH{sub 2}] in different solvents are studied. • Tb(III) complex shows good binding affinity to FS DNA with K{sub b}=(8.06±0.01)×10{sup 3} M{sup −1}. • Viscosity of DNA almost unchanged by increasing amount of Tb complex. • CD spectrum of DNA has a little change with increasing amount of Tb complex. • Thermodynamic parameters indicate that the binding reaction is entropically driven.

  20. Synthesis and photoluminescence properties of CaSiO3:Eu3+ spheres prepared by the reverse micelles soft template

    International Nuclear Information System (INIS)

    Yang Liangzhun; Fang Min; Du Lifen; Zhang Zhaojie; Ren Liwen; Yu Xibin

    2008-01-01

    We report here the successful synthesis of CaSiO 3 :Eu 3+ spheres using the reverse micelles soft template. The influence of the calcination temperature on the shape, crystallization and photoluminescence properties of the prepared spheres was investigated by DTA-TG, XRD, IR, SEM and PL. The results showed that the temperature of crystallization (from amorphous phase to β-CaSiO 3 ) is 668 deg. C. The temperature of phase transition (from β-CaSiO 3 to α-CaSiO 3 ) is 790 deg. C. The average size of CaSiO 3 :Eu 3+ spheres calcined at 700 deg. C was about 350 nm. The radiation was dominated by the red emission peak at 613 nm and the highest emission intensity was observed when the spheres were calcined at 700 deg. C. When calcined at 800 deg. C, the spheres are almost cracked and melted down, due to the high temperature

  1. Observation of many-body Coulomb interaction effects on the photoluminescence spectra of InAs/GaAs quantum dots

    International Nuclear Information System (INIS)

    Rihani, J.; Sedrine, N.B.; Sallet, V.; Oueslati, M.; Chtourou, R.

    2008-01-01

    InAs quantum dots (QDs) on GaAs (0 0 1) substrates were grown by Molecular Beam Epitaxy (MBE) using two growth temperatures. Photoluminescence (PL) pump power dependence measurements at low temperature were carried out for sample grown at higher temperature (520 deg. C). With increasing excitation density, the ground-state transition energy is found to decrease by 8 meV, while the excited-state transition energies exhibit resonance behaviour. The redshift of the ground-state emission was related to the band-gap renomalization (BGR) effect whereas the blueshift of the excited-state emissions was assigned to the compensation between filling of fine structure states and BGR effects. Using a quasi-resonant PL measurement, we have shown that the renormalization of the band-gap had to occur in the QD barrier

  2. Radio- and photoluminescence properties of Ce/Tb co-doped glasses with huntite-like composition

    Science.gov (United States)

    Lorenzi, Roberto; Golubev, Nikita V.; Ziaytdinova, Mariyam Z.; Jarý, Vítězslav; Babin, Vladimir; Malashkevich, Georgii E.; Paleari, Alberto; Sigaev, Vladimir N.; Fasoli, Mauro; Nikl, Martin

    2018-04-01

    Optical properties of yttria-aluminoborate (YAB) glasses with general composition 10(CexTbyY(1-x-y))-30Al2O3-60B2O3 are investigated and compared with data available on YAB crystals with huntite-like structure. Ce doped samples show optical features ascribable to preferential location of rare earth ions in sites with specific geometry similar to that observed in crystalline structures. Samples prepared with Tb ions as emission activator and Ce ions as sensitizer have been studied within the framework of non-radiative energy transfer. The resulting Förster radius is of 4.6 ± 0.5 Å comparable with that observed in Ce/Tb co-doped YAl3(BO3)4 crystals. The investigated materials possess radio- and photoluminescence emission efficiencies and performances comparable to that of crystalline counterparts with the advantage of having easiness of preparation and workability typical of glassy systems.

  3. Exciplex electroluminescence and photoluminescence spectra of the new organic materials based on zinc complexes of sulphanylamino-substituted ligands.

    Science.gov (United States)

    Kaplunov, Mikhail G; Krasnikova, Svetlana S; Nikitenko, Sergey L; Sermakasheva, Natalia L; Yakushchenko, Igor K

    2012-04-03

    We have investigated the electroluminescence spectra of the electroluminescent devices based on the new zinc complexes of amino-substituted benzothiazoles and quinolines containing the C-N-M-N chains in their chelate cycles. The spectra exhibit strong exciplex bands in the green to yellow region 540 to 590 nm due to interaction of the excited states of zinc complexes and triaryl molecules of the hole-transporting layer. For some devices, the intrinsic luminescence band of 460 nm in the blue region is also observed along with the exciplex band giving rise to an almost white color of the device emission. The exciplex band can be eliminated if the material of the hole-transporting layer is not a triarylamine derivative. We have also found the exciplex emission in the photoluminescence spectra of the films containing blends of zinc complex and triphenylamine material.

  4. Local microstructure and photoluminescence of Er-doped 12CaO·7Al2O3 powder

    Institute of Scientific and Technical Information of China (English)

    WANG Dan; LIU Yuxue; XU Changshan; LIU Yichun; WANG Guorui; LI Xinghua

    2008-01-01

    Er-doped 12CaO·7Al2O3 (C12A7:Er) powders were prepared using the sol-gel method followed by annealing inorganic precursors. X-ray diffraction (XRD), Raman and absorption spectra revealed that Er ions existed and substituted Ca2+ lattice site in C12A7. The photoluminescence of C12A7:Er at room temperature was observed in the visible and infrared region using 488 nm (2.54 eV) Ar+ line as excitation source, respectively. The sharp and intense green emission bands with multi-peaks around 520 nm and 550 nm correspond to the transitions from the excited states 2H11/2 and 4S3/2 to the ground state 4I15/2, respectively. Furthermore, red emission band around 650 nm was also observed. It was attributed to the electronic transition from excited states 4F9/2 to the ground state 4I15/2 inside 4f-shell of Er3+ ions. The intensive infrared emission at 1.54μm was attributed to the transition from the first excited states of 4I13/2 to the ground state (4I15/2). The temperature dependent photoluminescence of infrared emission showed that the integrated intensity reached a maximum value at near room temperature. The forbidden transitions of intra-4f shell electrons in free Er3+ ions were allowed in C12A7 owing to lack of the inversion symmetry in the Er3+ position in C12A7 crystal field. Our results suggested that C12A7:Er was a candidate for applications in Er-doped laser materials, and full color display.

  5. Photoactivation and perturbation of photoluminescent properties of aqueous ZnS nanoparticles: Probing the surfactant-semiconductor interfaces

    International Nuclear Information System (INIS)

    Mehta, S.K.; Kumar, Sanjay

    2011-01-01

    Graphical abstract: The variation in PL emission intensity of growing ZnS NPs during first hour of their growth depends upon the nature of surfactants used for their stabilization. Highlights: ► Photoluminescence (PL) intensity of growing ZnS NPs increases linearly with time. ► Significant PL enhancement in anionic surfactant stabilized ZnS NPs on irradiation. ► PL decay with delay time after removing from UV-irradiation in all the surfactants. ► Better PL stability of ZnS NPs stabilized in anionic surfactants than cationic ones. - Abstract: The in situ photochemistry of aqueous colloidal ZnS has been studied in relation to variety of the surfactants as surface passivating agents. The photoluminescence (PL) intensity of ZnS nanoparticles (NPs) has been drastically enhanced as compared to their bare counterparts due to surface passivation by surfactants depending upon their molecular structure. Cationic surfactants of alkyltrimethylammonium bromide series with different chain lengths (C 16 , C 14 and C 12 ) have been tested. The PL emission of ZnS NPs decreases with decrease in chain length because of ineffective stabilization and passivation of surface because the larger sized NPs were produced in the surfactant with smaller chain length. On the other hand, three anionic surfactants with C 12 chain length with different head groups have been capable of comparatively effective passivation to produce stable NPs with better luminescence. The changing nature of surface states during growth and long time ripening of ZnS NPs has also been monitored by comparing time evolution PL emission in different surfactants. The influence of UV-light irradiation in enhancing the PL emission has been found to be surfactant structure dependent with maximum enhancement observed with the surfactants having π-electrons in their head group functionalities. The anionic surfactants also display better tendency to retain the enhanced PL of ZnS NPs for longer time durations.

  6. Lifetime studies of self-activated photoluminescence in heavily silicon-doped GaAs

    Science.gov (United States)

    Sauncy, T.; Palsule, C. P.; Holtz, M.; Gangopadhyay, S.; Massie, S.

    1996-01-01

    We report results of a detailed temperature dependence study of photoluminescence lifetime and continuous emission properties in silicon-doped GaAs. The primary focus is on a defect-related emission at 1.269 eV (T=20 K). GaAs crystals were grown using molecular-beam epitaxy with most of the experiments conducted on a sample having a carrier concentration of 4.9×1018 cm-3. The intensity is seen to decrease above 100 K, with no corresponding decrease in the measured lifetime of 9.63+/-0.25 ns. The intensity decrease implies an activation energy of 19+/-2 meV, which is approximately one order of magnitude smaller than what was previously obtained for similar defects in Czochralski-grown GaAs with other dopants. We interpret our results in terms of a configuration coordinate model and obtain a more complete picture of the energy-level structure. The experiments indicate that the upper level in the recombination process is about 20 meV below the conduction-band continuum, with the lower state approximately 300 meV above the valence band. Our results are consistent with the identification of the corresponding defect complex microstructure as being a silicon-at-gallium substitution, weakly interacting with a gallium vacancy second-nearest neighbor, known as the Si-Y defect complex.

  7. Oxygen vacancy effect on photoluminescence of KNb3O8 nanosheets

    Science.gov (United States)

    Li, Rui; Liu, Liying; Ming, Bangming; Ji, Yuhang; Wang, Ruzhi

    2018-05-01

    Fungus-like potassium niobate (KNb3O8) nanosheets have been synthesized on indium-doped tin oxide (ITO) glass substrates by a simple and environmental friendly two-step hydrothermal process. The prepared samples have been characterized by using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), High Resolution Transmission Electron Microscope (HRTEM), Fourier Transform Infra-Red Spectroscopy (FTIR), Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Furthermore, the photoluminescence (PL) of KNb3O8 nanosheets have been systematically studied. The results showed that the PL spectrum is between 300 and 645 nm with a 325 nm light excitation, which is divided into some sub-peaks. It is different from the perfect KNb3O8 nanosheets whose PL emission peaks located at near 433 nm. It should be originated from the effect of the oxygen (O) vacancies in the KNb3O8 nanosheets, which the PLs peaks can be found at about 490 nm and 530 nm by different position of O vacancy. The experimental results are in accordance with the first-principles calculations. Our results may present a feasible clue to estimate the defect position in KNb3O8 by the shape analysis of its spectrum of PLs.

  8. Defect chemistry in CuGaS2 thin films: A photoluminescence study

    International Nuclear Information System (INIS)

    Botha, J.R.; Branch, M.S.; Berndt, P.R.; Leitch, A.W.R.; Weber, J.

    2007-01-01

    In this paper, the radiative recombination in CuGaS 2 thin films, deposited by metalorganic vapour phase epitaxy (MOVPE), is studied by photoluminescence (PL) spectroscopy. From PL studies of several series of layers grown under various growth conditions, a clear picture emerges of the radiative emission dominating for Cu-rich and Ga-rich layers. For near-stoichiometric layers, weak excitonic recombination at ∼ 2.48 eV and a donor-acceptor line at ∼ 2.4 eV are observed in the low temperature PL spectra. In Cu-rich layers, a donor-acceptor band at ∼ 2.18 eV dominates, while a band at ∼ 2.25 eV dominates for slightly Ga-rich material. For Ga-rich layers, deviations from the ideal Cu/Ga ratio of more than a few percent strongly quenches the emission above 2 eV in favour of a very broad band at ∼ 1.8 eV. The PL response is discussed within the context of fluctuating potentials in compensated material and compared to available reports in literature

  9. Preparation and Photoluminescence of ZnO Comb-Like Structure and Nanorod Arrays

    Science.gov (United States)

    Yin, Song; Chen, Yi-qing; Su, Yong; Zhou, Qing-tao

    2007-06-01

    A large quantity of Zinc oxide (ZnO) comb-like structure and high-density well-aligned ZnO nanorod arrays were prepared on silicon substrate via thermal evaporation process without any catalyst. The morphology, growth mechanism, and optical properties of the both structures were investigated using XRD, SEM, TEM and PL. The resulting comb-teeth, with a diameter about 20 nm, growing along the [0001] direction have a well-defined epitaxial relationship with the comb ribbon. The ZnO nanorod arrays have a diameter about 200 nm and length up to several micrometers growing approximately vertical to the Si substrate. A ZnO film was obtained before the nanorods growth. A growth model is proposed for interpreting the growth mechanism of comb-like zigzag-notch nanostructure. Room temperature photoluminescence measurements under excitation wavelength of 325 nm showed that the ZnO comb-like nanostructure has a weak UV emission at around 384 nm and a strong green emission around 491 nm, which correspond to a near band-edge transition and the singly ionized oxygen vacancy, respectively. In contrast, a strong and sharp UV peak and a weak green peak was obtained from the ZnO nanorod arrays.

  10. Dominant ultraviolet-blue photoluminescence of ZnO embedded into synthetic opal

    International Nuclear Information System (INIS)

    Abrarov, S.M.; Yuldashev, Sh.U.; Kim, T.W.; Lee, S.B.; Kwon, H.Y.; Kang, T.W.

    2005-01-01

    The temperature-dependent photoluminescence (PL) characteristics of zinc oxide (ZnO) embedded into the voids of synthetic opal were studied. ZnO was infiltrated into opal from aqueous solution with zinc nitrate precursor followed by thermal annealing. The PL spectra of the ZnO powder exhibit very high and broad emission peaks in the green region due to crystal defects, such as oxygen vacancies and zinc ion interstitials. In contrast to the PL spectra of ZnO powder, nanocrystals of ZnO embedded into the voids of FCC packed opal matrix exhibit dominant ultraviolet (UV)-blue and rapidly decreasing green PL emissions with decreasing temperature. The temperature-dependent PL characteristics show that the green band suppression in the ZnO nanocrystals is due to the influence of photonic crystal. The infiltration of nanoparticles into synthetic opal may be used for the fabrication of polycrystalline ZnO with dominant UV-blue PL. These results indicate that the luminescent materials embedded into photonic crystal may be promising for the fabrication of the RGB pixels in full-color displays

  11. Photoluminescence and electroluminescence of a tripodal compound containing 7-diethylamino-coumarin moiety

    Energy Technology Data Exchange (ETDEWEB)

    Yu Tianzhi; Zhang Peng; Zhang Hui; Meng Jing; Fan Duowang [Key Laboratory of Opto-Electronic Technology and Intelligent Control (Lanzhou Jiaotong University), Ministry of Education, Lanzhou 730070 (China); Zhao Yuling; Dong Wenkui [School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070 (China)], E-mail: ytz823@hotmail.com

    2008-12-07

    A novel tripodal compound, tris[2-(7-diethylamino-coumarin-3-carboxamide)ethyl]amine (Tren-C), was synthesized and characterized by elemental analysis, infrared and {sup 1}H-NMR spectra. The photoluminescent (PL) and electroluminescent properties of Tren-C were investigated. Tren-C exhibits different colour emissions in solid states and solutions. The electroluminescence devices comprising vacuum vapour-deposited films using the compound as a dopant were fabricated, showing blue emissions that are identical to its PL spectrum in chloroform solutions. With the device structure of indium tin oxide (ITO)/4, 4', 4''-tris-N-naphthyl-N-phenylamino-triphenylamine (2-TNATA) (5 nm)/N, N'-bis-(naphthyl)-N, N'-diphenyl-1, 1'-biphenyl-4, 4'-diamine (NPB) (40 nm)/4, 4'-bis(9-carbazolyl) biphenyl (CBP) : Tren-C (0.5 wt%, 30 nm)/2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1, 3, 4-oxadiazole (Bu-PBD) (30 nm)/LiF (1 nm)/Al (100 nm), a maximum external quantum efficiency of 2.85%, a maximum luminous efficiency of 3.85 cd A{sup -1} and a maximum luminance of 1450 cd m{sup -2} are realized.

  12. Photoluminescence and lasing properties of MAPbBr3 single crystals grown from solution

    Science.gov (United States)

    Aryal, Sandip; Lafalce, Evan; Zhang, Chuang; Zhai, Yaxin; Vardeny, Z. Valy

    Recent studies of solution-grown single crystals of inorganic-organic hybrid lead-trihalide perovskites have suggested that surface traps may play a significant role in their photophysics. We study electron-hole recombination in single crystal MAPbBr3 through such trap states using cw photoluminescence (PL) and ps transient photoinduced absorption (PA) spectroscopies. By varying the depth of the collecting optics we examined the contributions from surface and bulk radiative recombination. We found a surface dominated PL band at the band-edge that is similar to that observed from polycrystalline thin films, as well as a weaker red-shifted emission band that originates from the bulk crystal. The two PL bands are distinguished in their temperature, excitation intensity and polarization dependencies, as well as their ps dynamics. Additionally, amplified spontaneous emission and crystal-related cavity lasing modes were observed in the same spectral range as the PL band assigned to the surface recombination. This work was funded by AFOSR through MURI Grant RA 9550-14-1-0037.

  13. Structure and Photoluminescence Properties of β-Ga2O3 Nanofibres Synthesized via Electrospinning Method

    Science.gov (United States)

    Sun, Chao; Deng, Jinxiang; Kong, Le; Chen, Liang; Shen, Zhen; Cao, Yisen; Zhang, Hao; Wang, Xiaoran

    2017-12-01

    This paper reported the β-Ga2O3 nanofibres which fabricated by electrospinning, and then calcining in oxygen at 750, 850, 950 and 1050°C. The structure and properties of β-Ga2O3 nanofibers have been studied though kinds of methods such as XRD, Photoluminescence (PL) spectrum, Raman spectrum, Scanning electron microscope (SEM) and FT-IR. The diameters of these nanofibres are from 60 to 130nm and the lengths of these nanofibres are about couple millimetres. The spectrum of PL which excitation at 365nm gave us the information that the emission peak of these β-Ga2O3 nanofibres is about 470nm, it may be coursed by the various defects including the vacancies of gallium and oxygen and the gallium-oxygen vacancy pairs as well, and observed that with the increasing of the annealing temperature, the emission peaks have a small bule swifting, and the crystallinity become better at the same time.

  14. High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals

    International Nuclear Information System (INIS)

    Kumar, E. Senthil; Mohammadbeigi, F.; Boatner, L.A.; Watkins, S.P.

    2016-01-01

    Group IV donors in ZnO are poorly understood, despite evidence that they are effective n-type dopants. Here we present high-resolution photoluminescence (PL) spectroscopy studies of unintentionally doped and Sn-doped ZnO single crystals grown by the chemical vapor transport method. Doped samples showed greatly increased emission from the I 10 bound exciton transition that was recently proven to be related to the incorporation of Sn impurities based on radio-isotope studies. The PL linewidths are exceptionally sharp for these samples, enabling a clear identification of several donor species. Temperature-dependent PL measurements of the I 10 line emission energy and intensity dependence reveal a behavior that is similar to other shallow donors in ZnO. Ionized donor bound-exciton and two-electron satellite transitions of the I 10 transition are unambiguously identified and yield a donor binding energy of 71 meV. In contrast to recent reports of Ge-related donors in ZnO, the spectroscopic binding energy for the Sn-related donor bound exciton follows a linear relationship with donor binding energy (Haynes rule) similar to recently observed carbon related donors, and confirming the shallow nature of this defect center, which was recently attributed to a Sn Zn double donor compensated by an unknown single acceptor.

  15. Channelling and electromagnetic radiation of channelling particles

    International Nuclear Information System (INIS)

    Kalashnikov, N.

    1983-01-01

    A brief description is presented of the channelling of charged particles between atoms in the crystal lattice. The specificities are discussed of the transverse motion of channelling particles as are the origin and properties of quasi-characteristic radiation of channelling particles which accompany transfers from one band of permissible energies of the transverse motion of channelling particles to the other. (B.S.)

  16. Tuning the Emission Energy of Chemically Doped Graphene Quantum Dots

    Directory of Open Access Journals (Sweden)

    Noor-Ul-Ain

    2016-11-01

    Full Text Available Tuning the emission energy of graphene quantum dots (GQDs and understanding the reason of tunability is essential for the GOD function in optoelectronic devices. Besides material-based challenges, the way to realize chemical doping and band gap tuning also pose a serious challenge. In this study, we tuned the emission energy of GQDs by substitutional doping using chlorine, nitrogen, boron, sodium, and potassium dopants in solution form. Photoluminescence data obtained from (Cl- and N-doped GQDs and (B-, Na-, and K-doped GQDs, respectively exhibited red- and blue-shift with respect to the photoluminescence of the undoped GQDs. X-ray photoemission spectroscopy (XPS revealed that oxygen functional groups were attached to GQDs. We qualitatively correlate red-shift of the photoluminescence with the oxygen functional groups using literature references which demonstrates that more oxygen containing groups leads to the formation of more defect states and is the reason of observed red-shift of luminescence in GQDs. Further on, time resolved photoluminescence measurements of Cl- and N-GQDs demonstrated that Cl substitution in GQDs has effective role in radiative transition whereas in N-GQDs leads to photoluminescence (PL quenching with non-radiative transition to ground state. Presumably oxidation or reduction processes cause a change of effective size and the bandgap.

  17. Photoluminescence optimization of Er-doped SiO{sub 2} films synthesized by radiofrequency magnetron sputtering with energetic treatments during and after deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cattaruzza, E., E-mail: cattaruz@unive.it; Battaglin, G.; Trave, E.; Visentin, F.

    2011-06-01

    By radiofrequency magnetron sputtering co-deposition we synthesized Er:SiO{sub 2} film 0.5 {mu}m thick on silica substrates, with Er content < 0.3 atomic %. By changing the preparation condition (during deposition we have used an additional negative bias voltage applied to the substrates for inducing a low-energy ion bombardment, with or without a contemporary heating) and by varying the thermal treatment after the synthesis (the best conditions were 1 h in the range 700-800 deg. C, in air) we have obtained an Er:SiO{sub 2} system with an intense photoluminescence emission at {lambda} = 1.54 {mu}m. The best-performing Er:SiO{sub 2} samples obtained by sputtering have shown a photoluminescence response comparable to that of the typical Er:SiO{sub 2} thin film systems obtained by conventional techniques used in applicative framework.

  18. Room temperature photoluminescence from In{sub x}Al{sub (1−x)}N films deposited by plasma-assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kong, W., E-mail: wei.kong@duke.edu; Jiao, W. Y.; Kim, T. H.; Brown, A. S. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Mohanta, A. [Oak Ridge Institute for Science and Education, Research Participation Program, U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC), Redstone Arsenal, Alabama 35898 (United States); Roberts, A. T. [Charles Bowden Research Lab, Army Aviation and Missile RD and E Center, Redstone Arsenal, Alabama 35898 (United States); Fournelle, J. [Department of Geoscience, University of Wisconsin, Madison, Wisconsin 53706 (United States); Losurdo, M. [Plasma Chemistry Research Center-CNR, via Orabona, 4-70126 Bari (Italy); Everitt, H. O. [Charles Bowden Research Lab, Army Aviation and Missile RD and E Center, Redstone Arsenal, Alabama 35898 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

    2014-09-29

    InAlN films deposited by plasma-assisted molecular beam epitaxy exhibited a lateral composition modulation characterized by 10–12 nm diameter, honeycomb-shaped, columnar domains with Al-rich cores and In-rich boundaries. To ascertain the effect of this microstructure on its optical properties, room temperature absorption and photoluminescence characteristics of In{sub x}Al{sub (1−x)}N were comparatively investigated for indium compositions ranging from x = 0.092 to 0.235, including x = 0.166 lattice matched to GaN. The Stokes shift of the emission was significantly greater than reported for films grown by metalorganic chemical vapor deposition, possibly due to the phase separation in these nanocolumnar domains. The room temperature photoluminescence also provided evidence of carrier transfer from the InAlN film to the GaN template.

  19. Channel Modeling

    Science.gov (United States)

    Schmitz, Arne; Schinnenburg, Marc; Gross, James; Aguiar, Ana

    For any communication system the Signal-to-Interference-plus-Noise-Ratio of the link is a fundamental metric. Recall (cf. Chapter 9) that the SINR is defined as the ratio between the received power of the signal of interest and the sum of all "disturbing" power sources (i.e. interference and noise). From information theory it is known that a higher SINR increases the maximum possible error-free transmission rate (referred to as Shannon capacity [417] of any communication system and vice versa). Conversely, the higher the SINR, the lower will be the bit error rate in practical systems. While one aspect of the SINR is the sum of all distracting power sources, another issue is the received power. This depends on the transmitted power, the used antennas, possibly on signal processing techniques and ultimately on the channel gain between transmitter and receiver.

  20. Channeling experiment

    International Nuclear Information System (INIS)

    Abelin, H.; Birgersson, L.; Widen, H.; Aagren, T.; Moreno, L.; Neretnieks, I.

    1990-07-01

    Channeling of water flow and tracer transport in real fractures in a granite body at Stripa have been investigated experimentally. The experimental site was located 360 m below the ground level. Two kinds of experiments were performed. In the single hole experiments, 20 cm diameter holes were drilled about 2.5 m into the rock in the plane of the fracture. Specially designed packers were used to inject water into the fracture in 5 cm intervals all along the fracture trace in the hole. The variation of the injection flowrates along the fracture were used to determine the transmissivity variations in the fracture plane. Detailed photographs were taken from inside the hole and the visual fracture aperture was compared with the injection flowrates in the same locations. Geostatistical methods were used to evaluate the results. Five holes were measured in great detail. In addition 7 holes were drilled and scanned by simpler packer systems. A double hole experiment was performed where two parallel holes were drilled in the same fracture plane at nearly 2 m distance. Pressure pulse tests were made between the holes in both directions. Tracers were injected in 5 locations in one hole and monitored for in many locations in the other hole. The single hole experiment and the double hole experiment show that most of the fracture planes are tight but that there are open sections which form connected channels over distances of at least 2 meters. It was also found in the double hole experiment that the investigated fracture was intersected by at least one fracture between the two holes which diverted a large amount of the injected tracers to several distant locations at the tunnel wall. (authours)