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Sample records for hgi2 near-bandgap photoluminescence

  1. Growth and characterization of HgI2, PbI2 and PbI2:HgI2 layered semiconductors

    Directory of Open Access Journals (Sweden)

    Manoel E.R.

    1999-01-01

    Full Text Available This paper presents a methodology for the preparation of a-HgI2 by Physical Vapor Transport and of PbI2 crystals using the Bridgman technique. The results of the growth of HgI2 diluted in PbI2 by the Bridgman technique are shown for the first time, its limit of solubility having been determined at 600 ppm of HgI2 in the PbI2 matrix. Optical absorption, photoluminescence and electrical conductivity measurements show that the crystals prepared are of good crystalline quality.

  2. Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

    Science.gov (United States)

    Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

    2002-01-01

    Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

  3. Synthesis and characterization of HgI2 nanoparticles for films nucleation

    Science.gov (United States)

    Barthaburu, María Pérez; Galain, Isabel; Mombrú, Maia; Aguiar, Ivana; Olivera, Alvaro; Pereira, Heinkel Bentos; Fornaro, Laura

    2017-01-01

    With the aim of controlling the first steps in HgI2 film growth onto amorphous substrates, we employed HgI2 nanoparticles for nucleation. Hg(NO3)2 and NaI were used for obtaining HgI2 in water with and without citric or oxalic acid as capping agents. These samples were then subjected to a hydrothermal treatment at a constant temperature of 120 ºC during 2 h. All samples were washed, centrifuged and dried. This method presents a facile route for obtaining HgI2 nanoparticles and is easily scalable. HgI2 tetragonal phase was confirmed by powder X-ray diffraction. Nanoparticles were characterized in their size and morphology by transmission electron microscopy and the capping agent presence was studied by infrared spectroscopy. HgI2 nanoparticles synthesized in octadecene, previously reported, as well as nanoparticles obtained in the present work, were used for nucleation onto amorphous substrates. They were deposited onto floating silica glass by spin coating and the morphology of the layer was studied by atomic force microscopy. The results we obtained are the first involving HgI2 nucleation by spin coating, and are very promising for improving the film growth orientation and therefore the current applications of this material, as well as for opening new ones.

  4. HgI2 nanostructures obtained hydrothermally for application in ionizing radiation detection

    Science.gov (United States)

    Pérez Barthaburu, María; Galain, Isabel; Aguiar, Ivana; Bentos Pereira, Heinkel; Fornaro, Laura

    2016-11-01

    The compound semiconductor HgI2 has been widely studied and employed as a material for ionizing radiation detection. Monocrystal growth is an intricate method for obtaining materials for this application. With the aim of finding a simpler and more effective way to develop ionizing radiation detectors, we employed HgI2 nanostructures subjected to a hydrothermal treatment and then pressed for this purpose. In the synthesis procedure, aqueous solutions of Hg(NO3)2 and NaI were mixed until their reaction completed and the suspension obtained was then placed in a homemade autoclave and heated at 120 °C for 2, 10 or 24 h. We confirmed the HgI2 tetragonal phase by powder XRD in all cases, independently of the synthesis conditions employed. Nanoparticles were characterized by their size and morphology by TEM. We used the HgI2 nanostructures to obtain a pellet by applying 0.7 GPa of pressure at room temperature. The pellet was then used to construct the detector, and we studied the electrical properties of the detector and its response to 241Am sources of different exposure rates. The resistivity and signal-to-noise ratio obtained are of the order of those reported for HgI2 detectors assembled with monocrystals. The results obtained in this work encourage us to work further on this topic, improving the method, scaling the detector’s size and studying its spectrometric grade.

  5. Photoelectronic properties of HgI2 crystals for nuclear radiation detection

    Indian Academy of Sciences (India)

    S L Sharma; H N Acharya

    2002-04-01

    Photoelectronic properties of red mercuric iodide single crystals, grown from its saturated solution in tetrahydrofuran, have been studied for the wavelength range 450-700 nm at temperatures 80, 110, 175, 235 and 300 K. Various aspects of the optical generation of charge carriers have been discussed. The computer simulation of the room temperature photoconductivity has generated the optimized values of the mobility-lifetime products (ee = 5.67 × 10-5 cm2/V, hh = 0.18 × 10-5 cm2/V), and surface recombination velocities (e = 3.2 × 105 cm/s, h = 4.5 × 105 cm/s) of the charge carriers in these crystals. The estimated values of the electron and hole drift lengths for typical electric fields suggest that, under the negative electrode illumination, THF -HgI2 crystals have high potential as regards to their use as phptodetectors in most of the scintillation spectrometers.

  6. Electrical properties of solid iodo mercurates resulting from the reaction of HgI2 with alcaline iodides

    Science.gov (United States)

    Ponpon, J. P.; Amann, M.

    2005-01-01

    Potassium iodide solutions are currently used during the fabrication process of mercuric iodide based nuclear radiation detectors. However, KI treatment leaves the HgI2 surface covered with a residual compound (namely the potassium tri-iodo mercurate) which has a significant influence on the surface properties and stability of mercuric iodide devices and therefore on the detectors characteristics. Looking for other solutions to etch mercuric iodide, we found it interesting to investigate the electrical properties of the compounds which may form when etching HgI2 in NH4I, NaI, and RbI. For this purpose, solid iodo mercurates with the cations ammonium, sodium, and rubidium, have been prepared by reacting HgI2 with the solutions of interest. Study of the electrical properties of these samples and comparison with those of potassium tri-iodo mercurate ones, especially with respect to humidity, indicates noticeable stability differences in presence of water vapour. This could have interesting consequences on the surface cleaning of mercuric iodide.

  7. Influence of water and water vapour on the characteristics of KI treated HgI 2 detectors

    Science.gov (United States)

    Ponpon, J. P.; Amann, M.; Sieskind, M.

    After being cleaned using a potassium iodide solution in water followed by a water rinse, the surface of mercuric iodide is covered by a chemical complex identified as being KHgI 3·H 2O. This compound can adsorb large quantities of water and its electrical properties are strongly sensitive to water and water vapour. The consequences on the manufacturing and storing conditions (especially the relative humidity), of mercuric iodide-based devices are therefore of great concern. They are illustrated by the study of the electrical and spectrometric properties of HgI 2 nuclear radiation detectors.

  8. Near-bandgap optical properties of pseudomorphic GeSn alloys grown by molecular beam epitaxy

    Science.gov (United States)

    D'Costa, Vijay Richard; Wang, Wei; Yeo, Yee-Chia

    2016-08-01

    We investigated the compositional dependence of the near-bandgap dielectric function and the E0 critical point in pseudomorphic Ge1-xSnx alloys grown on Ge (100) substrate by molecular beam epitaxy. The complex dielectric functions were obtained using spectroscopic ellipsometry from 0.5 to 4.5 eV at room temperature. Analogous to the E1 and E1+Δ1 transitions, a model consisting of the compositional dependence of relaxed alloys along with the strain contribution predicted by the deformation potential theory fully accounts for the observed compositional dependence in pseudomorphic alloys.

  9. Thermal radiation and low-temperature-vapour growth of HgI 2 crystal in production furnace

    Science.gov (United States)

    Roux, A.; Fedoseyev, A.; Roux, B.

    1993-06-01

    Heat exchanges in a sealed ampoule in the LTVG (low temperature vapour growth) furnace have been modelled in order to compute temperature fields and control the growth of HgI 2 crystals from vapour phase at low temperatures. We use a coupled conductive-radiative model to determine the shapes of the source and the crystal at different equilibrium states (i.e. without growth rate). The model involves conductivity anisotropy in the crystal and radiative exchanges between grey and diffuse surfaces (source and crystal interfaces, Pyrex walls), which are considered as opaque. Internal buoyancy effect is not taken into account as the pressure inside the ampoule is very small. The source temperature is fixed. For different undercoolings, i.e. for different cold finger temperatures, the "equilibrium" isotherm between the source/gas and crystal/gas interface has been numerically obtained. This "equilibrium" isotherm, which is associated with the stop of the growing process, gives a crystal shape. This shape is compared with experimental results given by the ETH-Zürich group. The model would permit a better understanding and control of the future HgI 2 crystal growth experiment. The computations are performed using a finite element package (FIDAP).

  10. Conductive-radiative model for predicting the shape of HgI2 crystal grown in the LTVG furnace

    Science.gov (United States)

    Roux, A.; Fedoseyev, A.; Roux, Bernard

    1992-08-01

    The modeling of heat exchanges in a sealed ampoule in the LTVG (Low Temperature Vapor Growth) furnace is focused upon, in order to compute temperature fields and control the growth of HgI2 crystals from vapor phase at low temperatures. A coupled conductive radiative model was used to determine the shape of the source and the crystal at different equilibrium states (that is, without growth rate). The model involves conductivity anisotropy in the crystal and radiative exchanges between grey and diffuse surfaces (source and crystal interfaces, pyrex walls), which are considered as opaque. Internal buoyancy effect is not taken into account as the pressure inside the ampoule is very small. The source temperature is fixed. For different undercoolings, that is, for different cold finger temperatures, the 'equilibrium' isotherm between the source/gas and crystal/gas interfaces was numerically obtained. This 'equilibrium' isotherm, which is associated with the stop of the growing process, gives a crystal shape. This shape is compared with experimental results given by the ETH-Zurich group. The model would permit a better understanding and control of the future HgI2 crystal growth experiment. The computations are performed using a finite element package (FIDAP).

  11. One-dimensional Zigzag Chain Composed of HgI2 Unit and 2,5-Bis(4-pyridyl)-1,3,4-thiadiazole: [HgI2(C12H8N4S)

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-Juan; MENG Ze-Rong; ZHANG Quan-Zheng; WU Xiao-Yuan; LU Can-Zhong

    2006-01-01

    The title compound, [HgI2(C12H8N4S)], has been synthesized and characterized by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/n with a =14.086(2), b = 6.0365(6), c = 20.286(2) (A), β = 108.818(5)°, V = 1632.7(3) (A)3, Mr = 694.67, Z = 4,Dc. = 2.826 g/cm3,μ - 13.331 mm1, F(000) = 1240, S = 1.108, the final R = 0.0438 and wR =0.0934 for 3085 observed reflections (I > 2σ(I)). The Hg(Ⅱ) atom is coordinated by two 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (L) molecules and two iodine anions in a distorted tetrahedral coordination geometry. Mercury atoms are linked by the organic ligands to form a one-dimensional zigzag chain. It is noteworthy that such 1D zigzag chains are extended into a two-dimensional double layer framework through I…I interactions.

  12. Lithography process for patterning HgI2 photonic devices

    Science.gov (United States)

    Mescher, Mark J.; James, Ralph B.; Hermon, Haim

    2004-11-23

    A photolithographic process forms patterns on HgI.sub.2 surfaces and defines metal sublimation masks and electrodes to substantially improve device performance by increasing the realizable design space. Techniques for smoothing HgI.sub.2 surfaces and for producing trenches in HgI.sub.2 are provided. A sublimation process is described which produces etched-trench devices with enhanced electron-transport-only behavior.

  13. 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.

  14. Photoluminescence of a Plasmonic Molecule.

    Science.gov (United States)

    Huang, Da; Byers, Chad P; Wang, Lin-Yung; Hoggard, Anneli; Hoener, Ben; Dominguez-Medina, Sergio; Chen, Sishan; Chang, Wei-Shun; Landes, Christy F; Link, Stephan

    2015-07-28

    Photoluminescent Au nanoparticles are appealing for biosensing and bioimaging applications because of their non-photobleaching and non-photoblinking emission. The mechanism of one-photon photoluminescence from plasmonic nanostructures is still heavily debated though. Here, we report on the one-photon photoluminescence of strongly coupled 50 nm Au nanosphere dimers, the simplest plasmonic molecule. We observe emission from coupled plasmonic modes as revealed by single-particle photoluminescence spectra in comparison to correlated dark-field scattering spectroscopy. The photoluminescence quantum yield of the dimers is found to be surprisingly similar to the constituent monomers, suggesting that the increased local electric field of the dimer plays a minor role, in contradiction to several proposed mechanisms. Aided by electromagnetic simulations of scattering and absorption spectra, we conclude that our data are instead consistent with a multistep mechanism that involves the emission due to radiative decay of surface plasmons generated from excited electron-hole pairs following interband absorption.

  15. The effect of dopant and optical micro-cavity on the photoluminescence of Mn-doped ZnSe nanobelts

    Science.gov (United States)

    2013-01-01

    Pure and Mn-doped ZnSe nanobelts were synthesized by a convenient thermal evaporation method. Scanning electron microscopy, X-ray powder diffraction, energy dispersive X-ray spectroscopy and corresponding element mapping, and transmission electron microscope were used to examine the morphology, phase structure, crystallinity, composition, and growth direction of as-prepared nanobelts. Raman spectra were used to confirm the effective doping of Mn2+ into ZnSe nanobelts. Micro-photoluminescence (PL) spectra were used to investigate the emission property of as-prepared samples. A dominant trapped-state emission band is observed in single ZnSeMn nanobelt. However, we cannot observe the transition emission of Mn ion in this ZnSeMn nanobelt, which confirm that Mn powder act as poor dopant. There are weak near-bandgap emission and strong 4T1 → 6A1 transition emission of Mn2+ in single ZnSeMnCl2 and ZnSeMn(CH3COO)2 nanobelt. More interesting, the 4T1 → 6A1 transition emission in ZnSeMn(CH3COO)2 nanobelt split into multi-bands. PL mapping of individual splitted sub-bands were carried out to explore the origin of multi-bands. These doped nanobelts with novel multi-bands emission can find application in frequency convertor and wavelength-tunable light emission devices. PMID:23829706

  16. Trace Explosives Detection by Photoluminescence

    OpenAIRE

    2004-01-01

    Some field tests in counter-terrorism efforts to detect explosive traces employ chemistries that yield colored products. We have examined a test kit of this kind, ETKPlus, based on widely used chemistries and employed extensively by the Israel Police. Our investigation focuses on the prospect of gaining sensitivity by replacing the normal colorimetric modality with photoluminescence detection, which, to our knowledge, has not been explored to date. We find two or more orders of magnitude sens...

  17. 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.

  18. Tough photoluminescent hydrogels doped with lanthanide.

    Science.gov (United States)

    Wang, Mei Xiang; Yang, Can Hui; Liu, Zhen Qi; Zhou, Jinxiong; Xu, Feng; Suo, Zhigang; Yang, Jian Hai; Chen, Yong Mei

    2015-03-01

    Photoluminescent hydrogels have emerged as novel soft materials with potential applications in many fields. Although many photoluminescent hydrogels have been fabricated, their scope of usage has been severely limited by their poor mechanical performance. Here, a facile strategy is reported for preparing lanthanide (Ln)-alginate/polyacrylamide (PAAm) hydrogels with both high toughness and photoluminescence, which has been achieved by doping Ln(3+) ions (Ln = Eu, Tb, Eu/Tb) into alginate/PAAm hydrogel networks, where Ln(3+) ions serve as both photoluminescent emitters and physical cross-linkers. The resulting hydrogels exhibit versatile advantages including excellent mechanical properties (∼ MPa strength, ≈ 20 tensile strains, ≈ 10(4) kJ m(-3) energy dissipation), good photoluminescent performance, tunable emission color, excellent processability, and cytocompatibility. The developed tough photoluminescent hydrogels hold great promises for expanding the usage scope of hydrogels.

  19. Nonlinear photoluminescence spectrum of single gold nanostructures.

    Science.gov (United States)

    Knittel, Vanessa; Fischer, Marco P; de Roo, Tjaard; Mecking, Stefan; Leitenstorfer, Alfred; Brida, Daniele

    2015-01-27

    We investigate the multiphoton photoluminescence characteristics of gold nanoantennas fabricated from single crystals and polycrystalline films. By exciting these nanostructures with ultrashort pulses tunable in the near-infrared range, we observe distinct features in the broadband photoluminescence spectrum. By comparing antennas of different crystallinity and shape, we demonstrate that the nanoscopic geometry of plasmonic devices determines the shape of the emission spectra. Our findings rule out the contribution of the gold band structure in shaping the photoluminescence.

  20. Photoluminescence of Conjugated Star Polymers

    Science.gov (United States)

    Ferguson, J. B.; Prigodin, N. V.; Epstein, A. J.; Wang, F.

    2000-10-01

    Higher dimensionality "star" polymers provide new properties beyond those found in their linear analogs. They have been used to improving electronic properties for nonlinear optics through exciton transfer and molecular antenna structures for example (M. Kawa, J. M. J. Frechet, Chem. Mater. 10, 286 (1998).). We report on photoluminescence properties of star polymers with a hyperbranched core (both hyperbranched phenlyene and hyperbranched triphenylamine) and polyhexylthiophene arms. The arm is a conjugated oligomer of polythiophene that has been investigated extensively for metallic like conductivity when doped as well as utilized in field effect transistors in its undoped form (A. Tsumara, H. Koezuka, T. Ando, Appl. Phys. Lett. 49, 1210 (1986).). The cores are respectively, a nonconjugated polymer in the case of hyperbranched phenlyene and a conjugated polymer in the case of hyperbranched triphenylamine. The photoluminesce spectrum (λ_max at 575 nm) is identical for both star polymers with the two electronically different hyperbranched cores and for linear polythiophene alone. We conclude the wave functions of the core and arms do not strongly interact to form states different from their individual states and excitons formed on the hyperbranched cores migrate to the lower bandgap polythiophene before recombining.

  1. Photoluminescence Characterization of NASICON Material

    Institute of Scientific and Technical Information of China (English)

    Yuehua He; Baofu Quan; Ying Wang; Chuanhui Cheng; Fengmin Liu; Biao Wang

    2006-01-01

    Besides gas sensitivity, NASICON (Na super ion conductor) material has luminescence characterization. In this paper, the photoluminescence properties of NASICON and doped-NASICON material are investigated. The NASICON material was synthesized by conventional sol-gel process, and doped with Er2O3, Tm2O3, Dy2O3, CsCl by 1%, 3%, 5% (mass ratio), respectively. The ultraviolet light (325 nm, He-Cd laser) excited luminescent emissions of the resulted powders are recorded vs. wavelength in the 330 nm to 650 nm range. The main peak of the pure NASICON is found at the wavelength of 474 nm (blue light), the transition energy is 2.616 eV. The luminescent intensity is weakened obviously after doping with Er2O3 and Tm2O3, but is increased after doping with Dy2O3 and 3% CsCl.

  2. Near-IR Photoluminescence of C60().

    Science.gov (United States)

    Strelnikov, Dmitry V; Kern, Bastian; Kappes, Manfred M

    2017-10-05

    We have observed that C60(+) ions isolated in cryogenic matrices show distinct near-IR photoluminescence upon excitation in the near-IR range. By contrast, UV photoexcitation does not lead to measurable luminescence. Near-IR C60(+) photoluminescence is a one-photon process. The emission is mainly concentrated in one band and corresponds to (2)A1u ← (2)E1g relaxation. We present experimental data for the Stokes shift, power, and temperature dependencies as well as the quantum efficiency of the photoluminescence. Our findings may be relevant for astronomy, considering recent unequivocal assignment of five diffuse interstellar bands to near-IR absorption bands of C60(+).

  3. 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 dimen......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...

  4. Manufacture and photoluminescent properties of molybdate phosphors

    Science.gov (United States)

    Lee, Kuan-Lin; Hsu, Ting-Chun; Chen, Lung-Chien

    2016-09-01

    In this experiment, the molybdate phosphors were manufactured by using the solid state amorphization with europium, yttrium and molybdenum. To investigate EuxYy(MoO4)3 phosphor characteristics, the europium and yttrium were blended to different of mole ratio. The europium composition can improve phosphors luminous intensity. Phosphors characteristics was measured by X-ray diffraction, SEM and photoluminescence. The X-ray diffraction and SEM displayed phosphors crystal structure. The photoluminescence of molybdate phosphors show that the best excitation spectra emitting position was at 614nm. The molybdate phosphors was excited by UV laser. Therefore, this molybdate phosphors was suitable for UV-LED.

  5. Detection of inter band gap photoluminescence in multicrystalline silicon wafer

    OpenAIRE

    Jerpetjøn, Lena-Marie

    2011-01-01

    Measurements executed at 300 K revealed photoluminescence solely from silicon. However, at 93 K the measurements revealed photoluminescence from both silicon and defects. The detected photoluminescence signal of silicon at 93 K was stronger though spectrally narrower than the signal detected at 300 K. Hence, the photoluminescence signal was affected by multi-phonon interactions. Two features, D1 and D2, were detected among other defects at 93 K. These two features have been put in relation t...

  6. Low Temperature Photoluminescence (PL) from High Electron Mobility Transistors (HEMTs)

    Science.gov (United States)

    2015-03-01

    TECHNICAL REPORT RDMR-WD-14-55 LOW TEMPERATURE PHOTOLUMINESCENCE (PL) FROM HIGH ELECTRON MOBILITY TRANSISTORS (HEMTS...DATE March 2015 3. REPORT TYPE AND DATES COVERED Final 4. TITLE AND SUBTITLE Low Temperature Photoluminescence (PL) From High Electron...temperature Photoluminescence (PL) from High Electron Mobility Transistor (HEMT) structures that have been modified by proton irradiation. The samples are

  7. Diagnostic meaning of intestinal wall photoluminescence changes

    Science.gov (United States)

    Besaha, R. M.; Hrynchuk, F. V.; Polyansky, I. Y.

    2006-05-01

    Diagnostics of inflammatory-destructive diseases of the abdominal cavity organs is performed by the determined spectra of luminescence of venous blood plasma. The shift of the photoluminescence maximum beginning with the wave-length 469 nm into short-wave zone proves the presence of the acute inflammatory-destructive diseases and exacerbation of the pathological process.

  8. Photoluminescent Detection of Dissolved Underwater Trace Explosives

    OpenAIRE

    2010-01-01

    A portable, rapid, and economical method for in situ trace explosive detection in aqueous solutions was demonstrated using photoluminescence. Using europium/thenoyltrifluoroacetone as the reagent, dissolved nitroglycerin was fluorescently tagged and detected in seawater solutions without sample preparation, drying, or preconcentration. The chemical method was developed in a laboratory setting and demonstrated in a flow-through configuration using lightweight, inexpensive, commercial component...

  9. Blue photoluminescent carbon nanodots from limeade.

    Science.gov (United States)

    Suvarnaphaet, Phitsini; Tiwary, Chandra Sekhar; Wetcharungsri, Jutaphet; Porntheeraphat, Supanit; Hoonsawat, Rassmidara; Ajayan, Pulickel Madhavapanicker; Tang, I-Ming; Asanithi, Piyapong

    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 490nm 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(3+)) detection in water compared to Fe(2+), Cu(2+), Co(2+), Zn(2+), Mn(2+) and Ni(2+) ions. The photoluminescence quenching of L-CnD solution under UV light is used to distinguish the Fe(3+) ions from others by naked eyes as low concentration as 100μM. 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.

  10. Emerging plasmonic nanostructures for controlling and enhancing photoluminescence.

    Science.gov (United States)

    Park, Jeong-Eun; Kim, Jiyeon; Nam, Jwa-Min

    2017-07-01

    Localised surface plasmon resonance endows plasmonic nanostructures with unique, powerful properties such as photoluminescence enhancement, which is a phenomenon based on the interaction between light and a metal nanostructure. In particular, photoluminescence modulation and enhancement are of importance to many research fields such as photonics, plasmonics and biosensing. In this minireview, we introduce basic principles of plasmonic-nanostructure photoluminescence and recently reported plasmonic nanostructures exhibiting surface-enhanced fluorescence and direct photoluminescence, with one-photon photoluminescence being of particular interest. Gaining insights into these systems not only helps understand the fundamental concepts of plasmonic nanostructures but also advances and extends their applications.

  11. Plasmon-modulated photoluminescence of individual gold nanostructures.

    Science.gov (United States)

    Hu, Hailong; Duan, Huigao; Yang, Joel K W; Shen, Ze Xiang

    2012-11-27

    In this work, we performed a systematic study on the photoluminescence and scattering spectra of individual gold nanostructures that were lithographically defined. We identify the role of plasmons in photoluminescence as modulating the energy transfer between excited electrons and emitted photons. By comparing photoluminescence spectra with scattering spectra, we observed that the photoluminescence of individual gold nanostructures showed the same dependencies on shape, size, and plasmon coupling as the particle plasmon resonances. Our results provide conclusive evidence that the photoluminescence in gold nanostructures indeed occurs via radiative damping of plasmon resonances driven by excited electrons in the metal itself. Moreover, we provide new insight on the underlying mechanism based on our analysis of a reproducible blue shift of the photoluminescence peak (relative to the scattering peak) and observation of an incomplete depolarization of the photoluminescence.

  12. Photoluminescence of Turkish purple jade (turkiyenite)

    Energy Technology Data Exchange (ETDEWEB)

    Hatipoglu, Murat, E-mail: murat.hatipoglu@deu.edu.tr [Dokuz Eyluel University, IMYO, Izmir Multidisciplinary Vocational School, Gemmology and Jewellery Programme, TR-35380 Buca-Izmir (Turkey); Dokuz Eyluel University, The Graduate School of Natural and Applied Sciences, Department of Natural Building Stones and Gem Stones, TR-35370 Buca-Izmir (Turkey); Basevirgen, Yasemin [Dokuz Eyluel University, IMYO, Izmir Multidisciplinary Vocational School, Gemmology and Jewellery Programme, TR-35380 Buca-Izmir (Turkey); Dokuz Eyluel University, The Graduate School of Natural and Applied Sciences, Department of Natural Building Stones and Gem Stones, TR-35370 Buca-Izmir (Turkey)

    2012-11-15

    The purple-colored unique gem material is only found in the Harmanc Latin-Small-Letter-Dotless-I k (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: Black-Right-Pointing-Pointer The purple-colored gem material is only found in the Harmanc Latin

  13. Photoassisted tuning of silicon nanocrystal photoluminescence.

    Science.gov (United States)

    Choi, Jonghoon; Wang, Nam Sun; Reipa, Vytas

    2007-03-13

    Silicon is a rather inefficient light emitter due to the indirect band gap electronic structure, requiring a phonon to balance the electron momentum during the interband transition. Fortunately, momentum requirements are relaxed in the 1-5 nm diameter Si crystals as a result of quantum confinement effects, and bright photoluminescence (PL) in the UV-vis range is achieved. Photoluminescent Si nanocrystals along with the C- and SiC-based nanoparticles are considered bioinert and may lead to the development of biocompatible and smaller probes than the well-known metal chalcogenide-based quantum dots. Published Si nanocrystal production procedures typically do not allow for the fine control of the particle size. An accepted way to make the H-terminated Si nanocrystals consists of anodic Si wafer etching with the subsequent breakup of the porous film in an ultrasound bath. Resulting H-termination provides a useful platform for further chemical derivatization and conjugation to biomolecules. However, a rather polydisperse mixture is produced following the ultrasonic treatment, leading to the distributed band gap energies and the extent of surface passivation. From the technological point of view, a homogeneous nanoparticle size mixture is highly desirable. In this study, we offer an efficient way to reduce the H-terminated Si nanocrystal diameter and narrow size distribution through photocatalyzed dissolution in a HF/HNO3 acid mixture. Si particles were produced using the lateral etching of a Si wafer in a HF/EtOH/H2O bath followed by sonication in deaerated methanol. Initial suspensions exhibited broad photoluminescence in the red spectral region. Photoassisted etching was carried out by adding the HF/HNO3 acid mixture to the suspension and exposing it to a 340 nm light. Photoluminescence and absorbance spectra, measured during dissolution, show the gradual particle size decrease as confirmed by the photoluminescence blue shift. The simultaneous narrowing of the

  14. Absorption and Photoluminescence in Organic Cavity QED

    CERN Document Server

    Herrera, Felipe

    2016-01-01

    Organic microcavities can be engineered to reach exotic quantum regimes of strong and ultrastrong light-matter coupling. However, the microscopic interpretation of their spectroscopic signals can be challenging due to the competition between coherent and dissipative processes involving electrons, vibrations and cavity photons. We develop here a theoretical framework based on the Holstein-Tavis-Cummings model and a Markovian treatment of dissipation to account for previously unexplained spectroscopic features of organic microcavities consistently. We identify conditions for the formation of dark vibronic polaritons, a new class of light-matter excitations that are not visible in absorption but lead to strong photoluminescence lines. We show that photon leakage from dark vibronic polaritons can be responsible for enhancing photoluminescence at the lower polariton frequency, and also explain the apparent breakdown of reciprocity between absorption and emission in the vicinity of the bare molecular transition fre...

  15. Zinc Oxide Nanorods and Their Photoluminescence Property

    Institute of Scientific and Technical Information of China (English)

    DAI Ying; ZHANG Yue; PEI Xin-mei; CHEN Wen

    2003-01-01

    Large-quantity growth of ZnO nanorods is achieved by oxidation of Zn powders with catalyst-free method.The products are characterized using X-ray diffraction,scanning electron microscopy,transmission electron microscopy and photoluminescence spectroscopy.The as-grown nanorods are structurally uniform with diameter ranging from 60 to 150nm and lengths of up to 5-8μm,and they are single crystalline in nature with growth direction parallel to [0001].Room-temperature photoluminescence spectrum of the nanorods shows a strong and sharp UV emission band at 385 nm and a weak and broad green emission band at 495 nm.The vapor-solid model is also proposed to explain the growth behavior of ZnO nanorods in our synthesis process.

  16. Magneto photoluminescence measurements of tungsten disulphide monolayers

    Science.gov (United States)

    Kuhnert, Jan; Rahimi-Iman, Arash; Heimbrodt, Wolfram

    2017-03-01

    Layered transition-metal dichalcogenides have attracted great interest in the last few years. Thinned down to the monolayer limit they change from an indirect band structure to a direct band gap in the visible region. Due to the monolayer thickness the inversion symmetry of the crystal is broken and spin and valley are coupled to each other. The degeneracy between the two equivalent valleys, K and K‧, respectively, can be lifted by applying an external magnetic field. Here, we present photoluminescence measurements of CVD-grown tungsten disulphide (WS2) monolayers at temperatures of 2 K. By applying magnetic fields up to 7 T in Faraday geometry, a splitting of the photoluminescence peaks can be observed. The magnetic field dependence of the A-exciton, the trion and three bound exciton states is discussed and the corresponding g-factors are determined.

  17. Photoluminescence of Ga(AsBi)

    Energy Technology Data Exchange (ETDEWEB)

    Rosemann, Nils; Chernikov, Alexej; Bornwasser, Verena; Koester, N.S.; Koch, Martin; Kolata, Kolja; Chetterjee, Sangam; Koch, Stephan W. [Fachbereich Physik, Philipps-Universitaet Marburg (Germany); Imhof, Sebastian; Wagner, Christian; Traenhardt, Angela [Institut fuer Physik, Technische Universitaet Chemnitz (Germany); Lu, Xianfeng; Johnson, Shane R. [Department of Electrical Engineering, Arizona State University, Tempe, AZ (United States); Beaton, Dan A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC (Canada); Tiedje, Thomas [Department of Electrical and Computer Engineering, University of Victoria, BC (Canada); Rubel, Oleg [Thunder Bay Regional Research Institute, Thunder Bay, ON (Canada); Department of Physics, Lakehead University, Thunder Bay, ON (Canada)

    2011-07-01

    Ga(AsBi) is a promising candidate for GaAs-based near-infrared emitters at telecommunication wavelength. To evaluate the potential of this material system we study the photoluminescence from such a bulk sample as function of pump power and lattice temperature. Strong disorder-related features are observed. To better quantify the experiments we analyze the data using a Monte Carlo approach. A two-scale model is introduced to account for both cluster localization and alloy disorder.

  18. 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.

  19. Ultraviolet photoluminescence of porous anodic alumina films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.

  20. Microscopic view on the ultrafast photoluminescence from photoexcited graphene.

    Science.gov (United States)

    Winzer, Torben; Ciesielski, Richard; Handloser, Matthias; Comin, Alberto; Hartschuh, Achim; Malic, Ermin

    2015-02-11

    We present a joint theory-experiment study on ultrafast photoluminescence from photoexcited graphene. On the basis of a microscopic theory, we reveal two distinct mechanisms behind the occurring photoluminescence: besides the well-known incoherent contribution driven by nonequilibrium carrier occupations, we found a coherent part that spectrally shifts with the excitation energy. In our experiments, we demonstrate for the first time the predicted appearance and spectral shift of the coherent photoluminescence.

  1. Photoluminescence Study of Copper Selenide Thin Films

    Science.gov (United States)

    Urmila, K. S.; Asokan, T. Namitha; Pradeep, B.

    2011-10-01

    Thin films of Copper Selenide of composition of composition Cu7Se4 with thickness 350 nm are deposited on glass substrate at a temperature of 498 K±5 K and pressure of 10-5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%) and Selenium (99.99%) as the elemental starting material. The deposited film is characterized structurally using X-ray Diffraction. The structural parameters such as lattice constant, particle size, dislocation density; number of crystallites per unit area and strain in the film are evaluated. Photoluminescence of the film is analyzed at room temperature using Fluoro Max-3 Spectrofluorometer.

  2. Laser photoluminescence spectroscopy of photodissociation fragments

    Science.gov (United States)

    Jackson, W. M.; Cody, R. J.

    1974-01-01

    Laser induced photoluminescence spectroscopy has been used to study the energy partitioning among CN fragments produced by the photodissociation of C2N2. The CN radicals are produced in both the A 2Pi and the X 2Sigma+ states. The A state is formed primarily in the nu-prime = 0 level, and the X state is formed in the lower vibrational levels. Since the photodissociation process does not produce the maximum amount of vibrational excitation in the CN fragments, it is suggested that the excess energy goes into either translational and/or rotational excitation of the CN.

  3. Gold Photoluminescence Wavelength and Polarization Engineering

    CERN Document Server

    Andersen, Sebastian K H; Bozhevolnyi, Sergey I

    2016-01-01

    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 develop a simple model that faithfully reproduces all features observed in our experiments showing also good quantitative agreement for the PL enhancement

  4. Photoluminescence in anthracene and it's derivatives

    Science.gov (United States)

    Vyas, Arpita; Mirgane, Nitin A.; Moharil, S. V.; Muley, Aarti Iyer

    2016-05-01

    The anthracene and it's derivative 9-chloro acridine and Anthracene-9-ylmethylacetate have prepared in Poly vinyl alcohol(PVOH). Their photoluminescence properties have studied. The pure anthracene has an emission at 424 and 443nm. The intense peak is observed at 465nm and shoulder at 407nm. The derivatives of anthracene Anthracene-9-ylmethylacetate shows an emission around 440nm for the excitation at 393nm and 9-chloro acridine shows emission around 360nm for the excitation at 290nm. The major problem of this organic material is the stability. The composites prepared in the medium of PVOH are more stable.

  5. 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.

  6. Strong white photoluminescence from annealed zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Zhenhua, E-mail: baizh46@gmail.com [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637457 (Singapore); Fujii, Minoru; Imakita, Kenji; Hayashi, Shinji [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-01-15

    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.

  7. Dynamics of two-photon photoluminescence in gold nanostructures

    Science.gov (United States)

    Biagioni, P.; Brida, D.; Huang, J.-S.; Kern, J.; Duò, L.; Hecht, B.; Finazzi, M.; Cerullo, G.

    2012-03-01

    We introduce the possibility of performing two-pulse correlation measurements in order to probe the dynamics of twophoton photoluminescence in Au nanostructures. Our preliminary results obtained from single-crystal Au nanorods are consistent with the two-step model for the photoluminescence process.

  8. Photoluminescence in amorphous MgSiO_3 silicate

    CERN Document Server

    Thompson, S P; Day, S J; Connor, L D; Evans, A

    2013-01-01

    Samples of amorphous MgSiO_3 annealed at temperature steps leading up to their crystallisation temperature show a rise in photoluminescence activity, peaking at ~450C. The photoluminescence band has a main peak at 595nm and a weaker peak at 624nm. We present laboratory data to show that the maximum in photoluminescence activity is related to substantial structural reordering that occurs within a relatively narrow temperature range. We attribute the origin of the photoluminescence to non-bridging oxygen hole centre defects, which form around ordered nano-sized domain structures as a result of the breakup of tetrahedral connectivity in the disordered inter-domain network, aided by the loss of bonded OH. These defects are removed as crystallisation progresses, resulting in the decrease and eventual loss of photoluminescence. Thermally processed hydrogenated amorphous silicate grains could therefore represent a potential carrier of extended red emission.

  9. Highly nonlinear photoluminescence threshold in porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Akcakir, O. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Therrien, J. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Yamani, Z. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Barry, N. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Yu, W. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Gratton, E. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    1999-12-27

    Porous silicon is excited using near-infrared femtosecond pulsed and continuous wave radiation at an average intensity of {approx}10{sup 6} W/cm{sup 2} (8x10{sup 10} W/cm{sup 2} peak intensity in pulsed mode). Our results demonstrate the presence of micron-size regions for which the intensity of the photoluminescence has a highly nonlinear threshold, rising by several orders of magnitude near this incident intensity for both the pulsed and continuous wave cases. These results are discussed in terms of stimulated emission from quantum confinement engineered intrinsic Si-Si radiative traps in ultrasmall nanocrystallites, populated following two-photon absorption. (c) 1999 American Institute of Physics.

  10. Photoluminescence of Silicon Nanocrystals in Silicon Oxide

    Directory of Open Access Journals (Sweden)

    L. Ferraioli

    2007-01-01

    Full Text Available Recent results on the photoluminescence properties of silicon nanocrystals embedded in silicon oxide are reviewed and discussed. The attention is focused on Si nanocrystals produced by high-temperature annealing of silicon rich oxide layers deposited by plasma-enhanced chemical vapor deposition. The influence of deposition parameters and layer thickness is analyzed in detail. The nanocrystal size can be roughly controlled by means of Si content and annealing temperature and time. Unfortunately, a technique for independently fine tuning the emission efficiency and the size is still lacking; thus, only middle size nanocrystals have high emission efficiency. Interestingly, the layer thickness affects the nucleation and growth kinetics so changing the luminescence efficiency.

  11. Photoluminescence studies in epitaxial CZTSe thin films

    Science.gov (United States)

    Sendler, Jan; Thevenin, Maxime; Werner, Florian; Redinger, Alex; Li, Shuyi; Hägglund, Carl; Platzer-Björkman, Charlotte; Siebentritt, Susanne

    2016-09-01

    Epitaxial Cu 2 ZnSnSe 4 (CZTSe) thin films were grown by molecular beam epitaxy on GaAs(001) using two different growth processes, one containing an in-situ annealing stage as used for solar cell absorbers and one for which this step was omitted. Photoluminescences (PL) measurements carried out on these samples show no dependence of the emission shape on the excitation intensity at different temperatures ranging from 4 K to 300 K . To describe the PL measurements, we employ a model with fluctuating band edges in which the density of states of the resulting tail states does not seem to depend on the excited charge carrier density. In this interpretation, the PL measurements show that the annealing stage removes a defect level, which is present in the samples without this annealing.

  12. Photoluminescence from Nd Doped Anodic Aluminium Oxide

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhang-Kai; PENG Xiao-Niu; SU Xiong-Rui; HAO Zhong-Hua

    2009-01-01

    We prepare Nd doped anodic aluminium oxide (Nd:AAO) template by using Nd doped aluminium foils through two-step anodization processes. Photoluminescence (PL) from the Nd:AAO template with the annealing temper-ature higher than 400℃ is observed, and the PL intensity enhanced with the increasing annealing temperature is found. We investigate the crystallization of Nd:AAO template and the excitation wavelength dependence of PL intensity, showing that the PL results from the Nd doped in the template. The approach presented may probably facilitate the fabricating of AAO with good light-emitting property, which can be used in fabrication of multifunctional nanosized films and may find applications in photonic devices.

  13. 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.

  14. Photoluminescent Patterned Papers Resulting from Printings of Polymeric Nanoparticles Suspension

    Directory of Open Access Journals (Sweden)

    Pierre Sarrazin

    2010-01-01

    Full Text Available The printability of a copolyfluorene-fluorenone (PFFO photoluminescent nanoparticle aqueous suspension on commercial tracing paper was here investigated. The nanoparticles suspension was obtained by miniemulsification of a suitable preformed photoluminescent organic polymer. The structural, physicochemical, and rheological characteristics of the nanoparticles suspension were first studied before considering its printability by inkjet and flexography techniques. The native properties of the nanoparticles suspension revealed to be more suitable for inkjet printing which was successfully used to print photoluminescent patterns using a very low amount of PFFO.

  15. Wide-field time-gated photoluminescence microscopy for fast ultrahigh-sensitivity imaging of photoluminescent probes.

    Science.gov (United States)

    Razali, Wan A W; Sreenivasan, Varun K A; Bradac, Carlo; Connor, Mark; Goldys, Ewa M; Zvyagin, Andrei V

    2016-08-01

    Fluorescence microscopy is a fundamental technique for the life sciences, where biocompatible and photostable photoluminescence probes in combination with fast and sensitive imaging systems are continually transforming this field. A wide-field time-gated photoluminescence microscopy system customised for ultrasensitive imaging of unique nanoruby probes with long photoluminescence lifetime is described. The detection sensitivity derived from the long photoluminescence lifetime of the nanoruby makes it possible to discriminate signals from unwanted autofluorescence background and laser backscatter by employing a time-gated image acquisition mode. This mode enabled several-fold improvement of the photoluminescence imaging contrast of discrete nanorubies dispersed on a coverslip. It enabled recovery of the photoluminescence signal emanating from discrete nanorubies when covered by a layer of an organic fluorescent dye, which were otherwise invisible without the use of spectral filtering approaches. Time-gated imaging also facilitated high sensitivity detection of nanorubies in a biological environment of cultured cells. Finally, we monitor the binding kinetics of nanorubies to a functionalised substrate, which exemplified a real-time assay in biological fluids. 3D-pseudo colour images of nanorubies immersed in a highly fluorescent dye solution. Nanoruby photoluminescence is subdued by that of the dye in continuous excitation/imaging (left), however it can be recovered by time-gated imaging (right). At the bottom is schematic diagram of nanoruby assay in a biological fluid. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

  17. Photoluminescent Detection of Dissolved Underwater Trace Explosives

    Directory of Open Access Journals (Sweden)

    Tye Langston

    2010-01-01

    Full Text Available A portable, rapid, and economical method for in situ trace explosive detection in aqueous solutions was demonstrated using photoluminescence. Using europium/thenoyltrifluoroacetone as the reagent, dissolved nitroglycerin was fluorescently tagged and detected in seawater solutions without sample preparation, drying, or preconcentration. The chemical method was developed in a laboratory setting and demonstrated in a flow-through configuration using lightweight, inexpensive, commercial components by directly injecting the reagents into a continually flowing seawater stream using a small amount of organic solvent (approximately 8% of the total solution. Europium's vulnerability to vibrational fluorescence quenching by water provided the mode of detection. Without nitroglycerin in the seawater solution, the reagent's fluorescence was quenched, but when dissolved nitroglycerin was present, it displaced the water molecules from the europium/thenoyltrifluoroacetone compound and restored fluorescence. This effort focused on developing a seawater sensor, but performance comparisons were made to freshwater. The method was found to perform better in freshwater and it was shown that certain seawater constituents (such as calcium have an adverse impact. However, the concentrations of these constituents are not expected to vary significantly from the natural seawater used herein.

  18. 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.

  19. Using quantum dot photoluminescence for load detection

    Energy Technology Data Exchange (ETDEWEB)

    Moebius, M., E-mail: martin.moebius@zfm.tu-chemnitz.de; Hartwig, M. [Technische Universität Chemnitz, Reichenhainer Straße, 09126 Chemnitz (Germany); Martin, J. [Fraunhofer Institute for Electronic Nano Systems, Technologie-Campus 3, 09126 Chemnitz (Germany); Baumann, R. R.; Otto, T.; Gessner, T. [Technische Universität Chemnitz, Reichenhainer Straße, 09126 Chemnitz (Germany); Fraunhofer Institute for Electronic Nano Systems, Technologie-Campus 3, 09126 Chemnitz (Germany)

    2016-08-15

    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.

  20. 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.

  1. Photoluminescence of P3HT nanoparticles

    Science.gov (United States)

    Dujovne, Irene; Labastide, Joelle; Baghgar, Mina; McKenna, Aidan; Barnes, Austin M.; Venkataraman, D.; Barnes, Michael D.

    2012-02-01

    Polythiophenes are semiconducting polymers that have been designed to crystallize. The photophysics of semicrystalline polythiophene and polythiophene-blends are the focus of intense research efforts across different disciplines. In these systems there is a competition between charge separation and recombination. Exciton diffusion length in organic-semiconductors is a major road-block for efficient solar energy harvesting devices since, for direct bandgap organic materials, this distance is about 10 nanometers. Thus, efficient extraction of photogenerated electrons and holes requires engineering polymer domain dimensions in this size range. In our initial investigations of the photophysics of isolated P3HT nanoparticles (15 - 130 nm), we have observed several intriguing size-dependent features in the single-particle photoluminescence (PL) connected with exciton diffusion and dissociation dynamics. In addition to the short-time behavior, we also observe size-dependent differences in PL decay at long times. In the 10 - 100 ns time regime, the PL originates not from radiative transitions of bound excitons, but rather from charge-separation followed by bi-polaron recombination--and thus provides an interesting measure of exciton fission probability within the nanoparticle.

  2. 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.

  3. Preparation of photoluminescent carbon dots-embedded polyelectrolyte microcapsules

    Institute of Scientific and Technical Information of China (English)

    Xiaoling Yang; Liming Peng; Jie Zong; Yihua Zhu

    2013-01-01

    Two types of photoluminescent carbon dots (CDs)-embedded polyelectrolyte (PE) microcapsules were successfully prepared via the layer-by-layer (LbL) assembly approach on sacrificial templates.For the first type,the PE microcapsules with CDs embedded in the cavity were produced from assembly of five pairs of poly(sodium 4-styrensulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) on CDs-pre-loaded meso-porous silica.For the second type,the PE microcapsules with CDs embedded in the wall were made of CDs and PAH,which were derived from SiO2 particles as templates.Microscope images confirmed the introduction of CDs into the two CDs-embedded microcapsules.These two microcapsules also retained the optical properties of free CDs.Photoluminescence spectra revealed that the two types of microcapsules had excitation-dependent photoluminescence behavior.When the excitation wavelength changed from 280 to 340 nm,photoluminescence emission peak of the PE microcapsules with CDs embedded in the cavity shifts from 369 to 377 nm,while for microcapsules with CDs embedded in the wall,emission peak shifts from 367 to 390 nm.Due to low toxicity,good hydrophilicity and photoluminescence properties of CDs,these two kinds of photo-luminescent microcapsules have competitive potential for application in carriers for imaging,drug delivery and biosensors.

  4. Development of aliphatic biodegradable photoluminescent polymers

    Science.gov (United States)

    Yang, Jian; Zhang, Yi; Gautam, Santosh; Liu, Li; Dey, Jagannath; Chen, Wei; Mason, Ralph P.; Serrano, Carlos A.; Schug, Kevin A.; Tang, Liping

    2009-01-01

    None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction. BPLPs can be further cross-linked into elastomeric cross-linked polymers, CBPLPs. We have shown representatively that BPLP-cysteine (BPLP-Cys) and BPLP-serine (BPLP-Ser) offer advantages over the traditional fluorescent organic dyes and quantum dots because of their preliminarily demonstrated cytocompatibility in vitro, minimal chronic inflammatory responses in vivo, controlled degradability and high quantum yields (up to 62.33%), tunable fluorescence emission (up to 725 nm), and photostability. The tensile strength of CBPLP-Cys film ranged from 3.25 ± 0.13 MPa to 6.5 ± 0.8 MPa and the initial Modulus was in a range of 3.34 ± 0.15 MPa to 7.02 ± 1.40 MPa. Elastic CBPLP-Cys could be elongated up to 240 ± 36%. The compressive modulus of BPLP-Cys (0.6) (1:1:0.6 OD:CA:Cys) porous scaffold was 39.60 ± 5.90 KPa confirming the soft nature of the scaffolds. BPLPs also possess great processability for micro/nano-fabrication. We demonstrate the feasibility of using BPLP-Ser nanoparticles (“biodegradable quantum dots”) for in vitro cellular labeling and noninvasive in vivo imaging of tissue engineering scaffolds. The development of BPLPs and CBPLPs represents a new direction in developing fluorescent biomaterials and could impact tissue engineering, drug delivery, bioimaging. PMID:19506254

  5. Photoluminescence from semiconductor cadmium selenide nanocrystals

    Science.gov (United States)

    Nazzal, Amjad Yousef

    In this dissertation, the photoluminescence (PL) emission properties from different CdSe nanocrystals (NCs) dispersed in polymer thin films were investigated. The PL spectroscopy was used as a probing tool to study core and surface-related emission properties of the CdSe NCs under investigation. The results found in these studies are promising from the point of view of fundamental understanding as well as the possible employments of the emission properties of CdSe NCs in certain technological applications. The studies presented in this dissertation include the following: (i) PL polarization spectroscopy of single CdSe NCs was performed on a system of colloidal CdSe quantum rods (QRs). Our experimental measurements suggest a strong polarization dependence of both excitation and emission, and confirm the unique linear dipole in the QRs along the long axis of the rod, i.e. the c axis of wurtzite structure, which is in agreement with the previous theoretical predictions. These results are very important because it represents an experimental test to the available theoretical models used in exploring the rich electronic spectra of these NC systems. These results also show the importance of the shape anisotropy on the electronic spectrum of NCs. (ii) Environmental effects on the PL from highly luminescent bare-core CdSe and core/shell CdSe/ZnS NCs were systematically investigated under different atmospheric environments and photo-irradiation conditions. In this study, the PL was used as a probe to detect changes in the electronic spectrum of the NCs due to photo-induced interactions on the surface of the NCs with the local surrounding atmosphere. Such studies are very important to provide a good understanding of the optimum operational conditions for emission applications of NCs in solid-state devices and also give a simple way of studying the surface of the NCs indirectly by investigating the surface interactions with different molecular systems and their effects on the

  6. Microcavity effects in the photoluminescence of hydrogenated amorphous silicon nitride

    Science.gov (United States)

    Serpenguzel, Ali; Aydinli, Atilla; Bek, Alpan

    1998-07-01

    Fabry-Perot microcavities are used for the alteration of photoluminescence in hydrogenated amorphous silicon nitride grown with and without ammonia. The photoluminescence is red-near-infrared for the samples grown without ammonia, and blue-green for the samples grown with ammonia. In the Fabry- Perot microcavities, the amplitude of the photoluminescence is enhanced, while its linewidth is reduced with respect to the bulk hydrogenated amorphous silicon nitride. The microcavity was realized by a metallic back mirror and a hydrogenated amorphous silicon nitride--air or a metallic front mirror. The transmittance, reflectance, and absorbance spectra were also measured and calculated. The calculated spectra agree well with the experimental spectra. The hydrogenated amorphous silicon nitride microcavity has potential for becoming a versatile silicon based optoelectronic device such as a color flat panel display, a resonant cavity enhanced light emitting diode, or a laser.

  7. Recent Advances in Understanding Delayed Photoluminescence in Colloidal Semiconductor Nanocrystals.

    Science.gov (United States)

    Marchioro, Arianna

    2017-02-22

    Colloidal semiconductor nanocrystals display remarkably bright, strongly size-dependent photoluminescence properties. Following photoexcitation of these materials, temporary charge carrier separation can occur where one or both charge carriers are trapped. Charge detrapping can reform the emissive state on long time scales up to seconds, causing delayed luminescence. This delayed luminescence has not yet been thoroughly explored, and appears to be closely associated with a phenomenon observed at the single particle level, i.e. photoluminescence intermittency (blinking). Here, some of our recent work on the delayed luminescence properties of nanocrystals of different chemical composition is reviewed. These results provide insight into the mechanism of carrier detrapping, and are discussed in the context of photoluminescence blinking.

  8. Dynamics of multi-photon photoluminescence in gold nanoantennas

    CERN Document Server

    Biagioni, P; Huang, J -S; Kern, J; Duò, L; Hecht, B; Finazzi, M; Cerullo, G

    2011-01-01

    We perform a combined study of the degree of nonlinearity and the temporal dynamics of multiphoton-excited photoluminescence (MPPL) in gold nanoantennas. At variance with standard gold two-photon photoluminescence (TPPL), the large photoluminescence enhancement in resonant nanostructures is sometimes found to involve more than two absorbed photons per emitted photon. By two-pulse correlation measurements of TPPL and MPPL we are able to address the particular dynamics of these mechanisms. Our data give direct evidence for the two-step model that has been proposed for gold TPPL and suggest that MPPL is characterized by very similar dynamics. Interestingly, for resonant antennas we observe a reduced MPPL relaxation time compared to off-resonant antennas.

  9. Two-photon excited ultraviolet photoluminescence of zinc oxide nanorods.

    Science.gov (United States)

    Zhu, Guangping; Xu, Chunxiang; Zhu, Jing; Lu, Changgui; Cui, Yiping; Sun, Xiaowei

    2008-11-01

    High density zinc oxide nanorods with uniform size were synthesized on (100) silicon substrate by vapor-phase transport method. The scanning electron microscopy images reveal that the nanorods have an average diameter of about 400 nm. The X-ray diffraction pattern demonstrates the wurtzite crystalline structure of the ZnO nanorods growing along [0001] direction. The single-photon excited photoluminescence presents a strong ultraviolet emission band at 394 nm and a weak visible emission band at 600 nm. When the ZnO nanorods were respectively pumped by various wavelength lasers from 520 nm to 700 nm, two-photon excited ultraviolet photoluminescence was observed. The dependence of the two-photon excited photoluminescence intensity on the excitation wavelength and power was investigated in detail.

  10. Chemical modification and the photoluminescence stabilization of titanic acid nanotubes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Titanic acid nanotubes (H2Ti2O4(OH)2) were surface-modified with cetyl alcohol through dehydration reaction because of existence of Ti-OH. The modified nanotubes were characterized by transmission electron microscopy (TEM), Fourier Transform Infrared (FT-IR) spectrometry and photoluminescence (PL) spectra. The results indicate that the modified nanotubes can be easily dispersed into organic solvent such as chloroform and toluene in contrast with the unmodified nanotubes, which makes it easier to be assembled by LB technique. Moreover, the Ti-O-CH2(CH2)14CH3 on the surface of the nanotubes can hinder the adsorption of water and consequently the photoluminescence property of the nanotubes can be stabilized. Even though kept in humid condition or in air for a long time, the modified nanotubes also maintain the special photoluminescence property in the visible region.

  11. Steady-state photoluminescent excitation characterization of semiconductor carrier recombination

    Energy Technology Data Exchange (ETDEWEB)

    Bhosale, J. S. [Intel Corporation, Hillsboro, Oregon 97124 (United States); Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Moore, J. E.; Wang, X.; Bermel, P.; Lundstrom, M. S. [Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2016-01-15

    Photoluminescence excitation spectroscopy is a contactless characterization technique that can provide valuable information about the surface and bulk recombination parameters of a semiconductor device, distinct from other sorts of photoluminescent measurements. For this technique, a temperature-tuned light emitting diode (LED) has several advantages over other light sources. The large radiation density offered by LEDs from near-infrared to ultraviolet region at a low cost enables efficient and fast photoluminescence measurements. A simple and inexpensive LED-based setup facilitates measurement of surface recombination velocity and bulk Shockley-Read-Hall lifetime, which are key parameters to assess device performance. Under the right conditions, this technique can also provide a contactless way to measure the external quantum efficiency of a solar cell.

  12. Photoluminescence spectra of TlInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wakita, Kazuki; Araki, Yoshito; Asaba, Ryo [Department of Electrical, Electronic and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, 275-0016 Narashino (Japan); Shim, YongGu [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuencho, 599-8531 Sakai (Japan); Mamedov, Nazim [Institute of Physics, National Academy of Sciences of Azerbaijan, H. Javid ave. 33, 1143 Baku (Azerbaijan)

    2012-12-15

    Photoluminescence spectra of TlInSe{sub 2} crystals with quasi one-dimensional structure have been investigated. The observed broad spectra have been found to result from overlapping of two peaks centered at 1.05 and 0.97 eV. Following the results of the examination of the excitation intensity dependence of the observed photoluminescence, the last peaks have been attributed to free-to-bound radiative transitions. The activation energy of donor or acceptor levels associated with these emissions has been tentatively evaluated. Furthermore, two sharp peaks located at 1.17 and 1.23 eV have been observed at 10 K in the excitation spectra of the observed photoluminescence (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Photoluminescence studies of single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1999-01-01

    Semiconductor quantum dots are considered a promising material system for future optical devices and quantum computers. We have studied the low-temperature photoluminescence properties of single InGaAs quantum dots embedded in GaAs. The high spatial resolution required for resolving single dots...... is obtained by exciting and detecting the photoluminescence through a microscope objective which is located inside the cryostat. Furthermore, e-beam lithography and mesa etching have been used to reduce the size of the detection area to a few hundred nanometers in diameter. These techniques allow us...

  14. Time-resolved photoluminescence spectroscopy of organic-plasmonic hybrids

    DEFF Research Database (Denmark)

    Leißner, Till; Brewer, Jonathan R.; Fiutowski, Jacek

    We study the optical properties of organic thin films and crystalline organic nanofibers as well as their interaction with plasmonic materials by means of laser-scanning fluorescence lifetime imaging microscopy (FLIM) and time-resolved photoluminescence spectroscopy (TR-PLS). The aim of our......-carrier dynamics in such systems. In this contribution we will show how the interaction of organic nanofibers placed on top of regular arrays of nanostructures leads to a significantly enhanced second-harmonic response and, at the same time, an increased decay rate of the photoluminescence lifetime....

  15. Photoluminescence lifetime measurements in InP wafers

    Science.gov (United States)

    Landis, Geoffrey A.; Jenkins, Phillip; Weinberg, Irving

    1991-01-01

    A simple apparatus to measure the minority carrier lifetime in InP has been developed. The technique stimulates the sample with a short pulse of light from a diode laser and measures the photoluminescence decay to extract the minority carrier lifetime. The photoluminescence lifetime in InP as a function of doping on both n- and p-type material is examined. The results also show a marked difference in the lifetime of n-type InP and p-type InP of similar doping levels. N-type InP shows a lifetime considerably longer than the expected radiative limited lifetime.

  16. Photoluminescence of Eu2+ Doped ZnS Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Man; GUO Hai-Qing; ZHANG Zhi-Hua; LIU Feng-Qi; WANG Zhan-Guo

    2000-01-01

    Eu2+ doped ZnS nanocrystals exhibit new luminescence properties because of the enlarged energy gap of nanocrys talline ZnS host due to quantum confinement effects. Photoluminescence emission at about 520nm from Eu2+ doped ZnS nanocrystals at room temperature is investigated by using photoluminescence emission and excitation spectroscopy. Such green emission with long lifetime (ms) is proposed to be a result of excitation, ionization, carriers recapture and recombination via Eu2+ centers in nanocrystalline ZnS host.

  17. Observation of nitrogen vacancy photoluminescence from an optically levitated nanodiamond

    CERN Document Server

    Neukirch, Levi P; Quidant, Romain; Novotny, Lukas; Vamivakas, A Nick

    2013-01-01

    We present the first evidence of nitrogen vacancy (NV) photoluminescence from a nanodiamond suspended in a free-space optical dipole trap at atmospheric pressure. The photoluminescence rates are shown to decrease with increasing trap laser power, but are inconsistent with a thermal quenching process. For a continuous-wave trap, the neutral charge state (NV$^0$) appears to be suppressed. Chopping the trap laser yields higher total count rates and results in a mixture of both NV$^0$ and the negative charge state (NV$^-$).

  18. 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...

  19. 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 posit...

  20. Photoluminescence of conjugated polymer blends at the nanoscale

    NARCIS (Netherlands)

    Jarzab, D.; Lu, M.; Nicolai, H.T.; Blom, P.W.M.; Loi, M.A.

    2011-01-01

    Here we report on a combined photoluminescence and morphological study of a polymer-polymer blend composed of a copolymer of derivatives of polyspirobifluorene and polyfluorene (PBFF) and a derivative of polyphenylene vinylene (MDMO-PPV). Evidence of partial Förster energy transfer from PBFF to

  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. 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

  3. 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

  4. Photoluminescence of conjugated polymer blends at the nanoscale

    NARCIS (Netherlands)

    Jarzab, Dorota; Lu, Mingtao; Nicolai, Herman T.; Blom, Paul W. M.; Loi, Maria A.

    2011-01-01

    Here we report on a combined photoluminescence and morphological study of a polymer-polymer blend composed of a copolymer of derivatives of polyspirobifluorene and polyfluorene (PBFF) and a derivative of polyphenylene vinylene (MDMO-PPV). Evidence of partial Forster energy transfer from PBFF to

  5. Dynamics of four-photon photoluminescence in gold nanoantennas.

    Science.gov (United States)

    Biagioni, Paolo; Brida, Daniele; Huang, Jer-Shing; Kern, Johannes; Duò, Lamberto; Hecht, Bert; Finazzi, Marco; Cerullo, Giulio

    2012-06-13

    Two-pulse correlation is employed to investigate the temporal dynamics of both two-photon photoluminescence (2PPL) and four-photon photoluminescence (4PPL) in resonant and nonresonant nanoantennas excited at a wavelength of 800 nm. Both 2PPL and 4PPL data are consistent with the same two-step model already established for 2PPL, implying that the first excitation step in 4PPL is a three-photon sp → sp direct interband transition. Considering energy and parity conservation, we also explain why 4PPL behavior is favored over, for example, three- and five-photon photoluminescence in the power range below the damage threshold of our antennas. Since sizable 4PPL requires larger peak intensities of the local field, we are able to select either 2PPL or 4PPL in the same gold nanoantennas by choosing a suitable laser pulse duration. We thus provide a first consistent model for the understanding of multiphoton photoluminescence generation in gold nanoantennas, opening new perspectives for applications ranging from the characterization of plasmonic resonances to biomedical imaging.

  6. Photoluminescence properties of polystyrene-hosted fluorophore thin films

    Directory of Open Access Journals (Sweden)

    Subha Chakraborty

    2016-12-01

    Full Text Available We report on a photo-luminescence study of four different fluorophores: Coumarin 6, 2,5-Diphenyloxazole (PPO, 1,4-Bis(5-phenyl-2-oxazolylbenzene (POPOP and Para-terpehnyl (PTP, doped in a polystyrene-based thin film. All of the samples are prepared by spin coating from a non-polar polymer solution at various concentrations. Their emission spectra and transient properties are characterized by photoluminescence measurements. Red-shifts in the emission spectra are observed for all four types of fluorophores as their concentration increases. We explain this phenomenon based on concentration dependence of solvatochromic effects and the results show good agreement with existing literature. We also show that the singlet-singlet annihilation processes are possibly a prevalent mechanism in the high concentration regime that affects the steady state and transient emission characteristics of the fluors. With the exception of PTP, photoluminescence quenching occurs as the fluorophore concentration in the polymer is increased. Rate equations for excited state decay mechanisms are analysed by considering different radiative and non-radiative energy transfer mechanisms. The results show consistency with our experimental observations. PTP shows the best photoluminescence results as an efficient fluor in the thin film, whereas PPO shows the strongest concentration dependent quenching and an anomalous lifetime distribution.

  7. O2 adsorption dependent photoluminescence emission from metal oxide nanoparticles.

    Science.gov (United States)

    Gheisi, Amir R; Neygandhi, Chris; Sternig, Andreas K; Carrasco, Esther; Marbach, Hubertus; Thomele, Daniel; Diwald, Oliver

    2014-11-21

    Optical properties of metal oxide nanoparticles are subject to synthesis related defects and impurities. Using photoluminescence spectroscopy and UV diffuse reflectance in conjunction with Auger electron spectroscopic surface analysis we investigated the effect of surface composition and oxygen adsorption on the photoluminescence properties of vapor phase grown ZnO and MgO nanoparticles. On hydroxylated MgO nanoparticles as a reference system, intense photoluminescence features exclusively originate from surface excitons, the radiative deactivation of which results in collisional quenching in an O2 atmosphere. Conversely, on as-prepared ZnO nanoparticles a broad yellow emission feature centered at hνEm = 2.1 eV exhibits an O2 induced intensity increase. Attributed to oxygen interstitials as recombination centers this enhancement effect originates from adsorbate-induced band bending, which is pertinent to the photoluminescence active region of the nanoparticles. Annealing induced trends in the optical properties of the two prototypical metal oxide nanoparticle systems, ZnO and MgO, are explained by changes in the surface composition and underline that particle surface and interface changes that result from handling and processing of nanoparticles critically affect luminescence.

  8. Photoluminescence of Zn-implanted GaN

    Science.gov (United States)

    Pankove, J. I.; Hutchby, J. A.

    1974-01-01

    The photoluminescence spectrum of Zn-implanted GaN peaks at 2.87 eV at room temperature. The emission efficiency decreases linearly with the logarithm of the Zn concentration in the range from 1 x 10 to the 18th to 20 x 10 to the 18th Zn/cu cm.

  9. Photoluminescence of spray pyrolysis deposited ZnO nanorods

    Science.gov (United States)

    2011-01-01

    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 PMID:21711895

  10. 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 film

  11. 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

  12. Photoluminescence of spray pyrolysis deposited ZnO nanorods.

    Science.gov (United States)

    Kärber, Erki; Raadik, Taavi; Dedova, Tatjana; Krustok, Jüri; Mere, Arvo; Mikli, Valdek; Krunks, Malle

    2011-04-21

    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.

  13. Fractals of graphene quantum dots in photoluminescence of shungite

    Science.gov (United States)

    Razbirin, B. S.; Rozhkova, N. N.; Sheka, E. F.; Nelson, D. K.; Starukhin, A. N.

    2014-05-01

    Viewing shungite as loosely packed fractal nets of graphene-based (reduced graphene oxide, rGO) quantum dots (GQDs), we consider photoluminescence of the latter as a convincing proof of the structural concept as well as of the GQD attribution to individual rGO fragments. We study emission from shungite GQDs for colloidal dispersions in water, carbon tetrachloride, and toluene at both room and low temperatures. As expected, the photoluminescence of the GQD aqueous dispersions is quite similar to that of synthetic GQDs of the rGO origin. The morphological study of shungite dispersions shows a steady trend of GQDs to form fractals and to drastically change the colloid fractal structure caused by the solvent exchange. Spectral study reveals a dual character of the emitting centers: individual GQDs are responsible for the spectra position while the fractal structure of GQD colloids ensures high broadening of the spectra due to structural inhomogeneity, thus causing a peculiar dependence of the photoluminescence spectra on the excitation wavelength. For the first time, photoluminescence spectra of individual GQDs were observed in frozen toluene dispersions, which paves the way for a theoretical treatment of the GQD photonics.

  14. Photoluminescence properties of polystyrene-hosted fluorophore thin films

    Science.gov (United States)

    Chakraborty, Subha; Harris, Katherine; Huang, Mengbing

    2016-12-01

    We report on a photo-luminescence study of four different fluorophores: Coumarin 6, 2,5-Diphenyloxazole (PPO), 1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOP) and Para-terpehnyl (PTP), doped in a polystyrene-based thin film. All of the samples are prepared by spin coating from a non-polar polymer solution at various concentrations. Their emission spectra and transient properties are characterized by photoluminescence measurements. Red-shifts in the emission spectra are observed for all four types of fluorophores as their concentration increases. We explain this phenomenon based on concentration dependence of solvatochromic effects and the results show good agreement with existing literature. We also show that the singlet-singlet annihilation processes are possibly a prevalent mechanism in the high concentration regime that affects the steady state and transient emission characteristics of the fluors. With the exception of PTP, photoluminescence quenching occurs as the fluorophore concentration in the polymer is increased. Rate equations for excited state decay mechanisms are analysed by considering different radiative and non-radiative energy transfer mechanisms. The results show consistency with our experimental observations. PTP shows the best photoluminescence results as an efficient fluor in the thin film, whereas PPO shows the strongest concentration dependent quenching and an anomalous lifetime distribution.

  15. Photoluminescence enhancement in thin films of PbSe nanocrystals

    NARCIS (Netherlands)

    Christova, C.G.; Stouwdam, J.W.; Eijkemans, T.J.; Silov, A.Y.; Van der Heijden, R.W.; Kemerink, M.; Janssen, R.A.J.; Salemink, H.W.M.

    2008-01-01

    Remarkable photoluminescence enhancement (PLE) in submonolayer films of PbSe nanocrystals (NCs) upon continuous illumination was observed. The intensity increase from films on InP substrates was highest in vacuum, while for films on Si/SiO2 substrates the PLE was stronger in air. The magnitude of th

  16. Photoluminescence of conjugated polymer blends at the nanoscale

    NARCIS (Netherlands)

    Jarzab, D.; Lu, M.; Nicolai, H.T.; Blom, P.W.M.; Loi, M.A.

    2011-01-01

    Here we report on a combined photoluminescence and morphological study of a polymer-polymer blend composed of a copolymer of derivatives of polyspirobifluorene and polyfluorene (PBFF) and a derivative of polyphenylene vinylene (MDMO-PPV). Evidence of partial Förster energy transfer from PBFF to MDMO

  17. 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

  18. Photoluminescence enhancement in thin films of PbSe nanocrystals

    NARCIS (Netherlands)

    Christova, C.G.; Stouwdam, J.W.; Eijkemans, T.J.; Silov, A.Y.; Van der Heijden, R.W.; Kemerink, M.; Janssen, R.A.J.; Salemink, H.W.M.

    2008-01-01

    Remarkable photoluminescence enhancement (PLE) in submonolayer films of PbSe nanocrystals (NCs) upon continuous illumination was observed. The intensity increase from films on InP substrates was highest in vacuum, while for films on Si/SiO2 substrates the PLE was stronger in air. The magnitude of

  19. Photoluminescence of conjugated polymer blends at the nanoscale

    NARCIS (Netherlands)

    Jarzab, D.; Lu, M.; Nicolai, H.T.; Blom, P.W.M.; Loi, M.A.

    2011-01-01

    Here we report on a combined photoluminescence and morphological study of a polymer-polymer blend composed of a copolymer of derivatives of polyspirobifluorene and polyfluorene (PBFF) and a derivative of polyphenylene vinylene (MDMO-PPV). Evidence of partial Förster energy transfer from PBFF to MDMO

  20. Photoluminescence enhancement in thin films of PbSe nanocrystals

    NARCIS (Netherlands)

    Christova, C.G.; Stouwdam, J.W.; Eijkemans, T.J.; Silov, A.Y.; Van der Heijden, R.W.; Kemerink, M.; Janssen, R.A.J.; Salemink, H.W.M.

    2008-01-01

    Remarkable photoluminescence enhancement (PLE) in submonolayer films of PbSe nanocrystals (NCs) upon continuous illumination was observed. The intensity increase from films on InP substrates was highest in vacuum, while for films on Si/SiO2 substrates the PLE was stronger in air. The magnitude of th

  1. Thermally enhanced photoluminescence for heat harvesting in photovoltaics

    Science.gov (United States)

    Manor, Assaf; Kruger, Nimrod; Sabapathy, Tamilarasan; Rotschild, Carmel

    2016-10-01

    The maximal Shockley-Queisser efficiency limit of 41% for single-junction photovoltaics is primarily caused by heat dissipation following energetic-photon absorption. Solar-thermophotovoltaics concepts attempt to harvest this heat loss, but the required high temperatures (T>2,000 K) hinder device realization. Conversely, we have recently demonstrated how thermally enhanced photoluminescence is an efficient optical heat-pump that operates in comparably low temperatures. Here we theoretically and experimentally demonstrate such a thermally enhanced photoluminescence based solar-energy converter. Here heat is harvested by a low bandgap photoluminescent absorber that emits thermally enhanced photoluminescence towards a higher bandgap photovoltaic cell, resulting in a maximum theoretical efficiency of 70% at a temperature of 1,140 K. We experimentally demonstrate the key feature of sub-bandgap photon thermal upconversion with an efficiency of 1.4% at only 600 K. Experiments on white light excitation of a tailored Cr:Nd:Yb glass absorber suggest that conversion efficiencies as high as 48% at 1,500 K are in reach.

  2. Detection of Organic Vapors Based on Photoluminescent Bragg-Reflective Porous Silicon Interferomete.

    Science.gov (United States)

    Ahn, Jihoon; Cho, Bomin; Kim, Sungsoo; Sohn, Honglae

    2015-07-01

    Novel photoluminescent Bragg-reflective porous silicon, exhibiting dual optical properties, both the optical reflectivity and photoluminescence, was developed and used for sensing organic vapors. Photoluminescent Bragg-reflective porous silicon samples were prepared by an electrochemical etch of n-type silicon under the illumination. The etching solution consisted of a 3:1 volume mixture of aqueous 48% hydrofluoric acid and absolute ethanol. The typical etch parameters for the generation of photoluminescent Bragg-reflective porous silicon involved a periodic square wave current with 50 repeats. The surface of photoluminescent Bragg-reflective porous silicon was characterized by a FT-IR spectroscopy. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic vapors. The shift of reflection band to the longer wavelength and the quenching of photoluminescence under the exposure of various organic vapors were observed.

  3. Radioluminescence and photoluminescence of Th:CaF$_2$ crystals

    CERN Document Server

    Stellmer, Simon; Schumm, Thorsten

    2015-01-01

    We study thorium-doped CaF$_2$ crystals as a possible platform for optical spectroscopy of the Th-229 nuclear isomer transition. We anticipate two major sources of background signal that might cover the nuclear spectroscopy signal: VUV-photoluminescence, caused by the probe light, and radioluminescence, caused by the radioactive decay of Th-229 and its daughters. We find a rich photoluminescence spectrum at wavelengths above 260 nm, and radioluminescence emission above 220 nm. This is very promising, as fluorescence originating from the isomer transition, predicted at a wavelength shorter than 200 nm, could be filtered spectrally from the crystal luminescence. Furthermore, we investigate the temperature-dependent decay time of the luminescence, as well as thermoluminescence properties. Our findings allow for an immediate optimization of spectroscopy protocols for both the initial search for the nuclear transition using synchrotron radiation, as well as future optical clock operation with narrow-linewidth lase...

  4. Photoluminescence and optical transmission of diffusion-pump oils.

    Science.gov (United States)

    Kroes, R. L.

    1973-01-01

    The photoluminescence and optical transmission of the four widely used diffusion-pump oils, DC-705, DC-704, Convalex-10, and Convoil-20, were measured. Each of the oils was found to be transparent throughout the visible region, showed some absorption in the near-UV region, and became very opaque below approximately 300 nm. Both Convalex-10 and Convoil-20 turned yellow after exposure to UV light. No such change was noted in DC-705 or DC-704. Photoluminescence was produced in each of the four oils when irradiated with UV light. Both DC-705 and DC-704 had a nearly identical luminescence spectra that peaked at 350 nm. The spectra of Convalex-10 and Convoil-20 were fairly complex, with several peaks in the visible region.

  5. Spatially resolved micro-photoluminescence imaging of porphyrin single crystals

    Science.gov (United States)

    Marin, Dawn M.; Castaneda, Jose; Kaushal, Meesha; Kaouk, Ghallia; Jones, Daniel S.; Walter, Michael G.

    2016-08-01

    We describe the collection of both time-resolved and steady-state micro-photoluminescence data from solution-grown single crystals of 5,15-bis(4-carbomethoxyphenyl)porphyrin (BCM2PP). Linking molecular orientation and structure with excited-state dynamics is crucial for engineering efficient organic solar cells, light-emitting diodes, and related molecular electronics. Photoluminescence features of single porphyrin crystals were imaged using a laser scanning confocal microscope equipped with time-correlated single photon counting (TCSPC). We show enhanced exciton lifetimes (τs1 = 2.6 ns) and stronger steady-state emission in crystalline BCM2PP samples relative to semicrystalline thin films (τs1 = 1.8 ns).

  6. Water-soluble, electroactive, and photoluminescent quaterthiophene-dinucleotide conjugates.

    Science.gov (United States)

    Alesi, Silvia; Brancolini, Giorgia; Melucci, Manuela; Capobianco, Massimo Luigi; Venturini, Alessandro; Camaioni, Nadia; Barbarella, Giovanna

    2008-01-01

    Quaterthiophene-dinucleotide conjugates 5'TA3'-t4-3'AT5', 5'AA3'-t4-3'AA5', and 5'TT3'-t4-3'TT5' (TA: thymidine-adenosine, AA: adenosine-adenosine, TT: thymidine-thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra- and intermolecular nucleobase-thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases.

  7. Photoluminescence and structural analysis of terbium doped porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Moadhen, A.; Elhouichet, H.; Oueslati, M. [Laboratoire de Physique de la Matiere Condensee - Equipe de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, 2092 El Manar, Tunis (Tunisia); Ferid, M. [Institut National de Recherche Scientifique et Technique, B.P. 95 Hammam-Lif 2050 (Tunisia); Daoudi, K. [Laboratoire de Physique de la Matiere Condensee - Equipe de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, 2092 El Manar, Tunis (Tunisia); Departement de Physique de la Matiere Condensee et Nanostructures, UMR CNRS 5586, Universite Claude Bernard Lyon 1, 69622 Villeurbanne Cedex (France); Canut, B.; Sandu, C.S.; Roger, J.A. [Departement de Physique de la Matiere Condensee et Nanostructures, UMR CNRS 5586, Universite Claude Bernard Lyon 1, 69622 Villeurbanne Cedex (France)

    2003-05-01

    Porous silicon (PS) doped with terbium (Tb{sup 3+}) has been prepared by impregnation of PS layers with chloride solution of terbium. The dependency of photoluminescence (PL) intensity on the Tb{sup 3+} concentration has been studied. Rutherford Back-scattering Spectrometry (RBS) spectra indicate clearly a total and uniform penetration of rare earth into the PS layers at all different percentages. PL spectra show an increase of the intensity of both Tb{sup 3+} peaks and PS band when the concentration of TbCl{sub 3} solution increases. The PL mechanism is discussed through time-resolved photoluminescence measurements, and in relation with thermal treatment effects. Transmission Electron Microscopy (TEM) technique has also been used to analyse the structure of this nanocomposite material. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  8. Photoluminescence of silicone oil treated by fluorocarbon plasma

    Institute of Scientific and Technical Information of China (English)

    Chen Tian; Ye Chao; Yuan Ying; Deng Yan-Hong; Ge Shui-Bin; Xu Yi-Jun; Ning Zhao-Yuan; Pan Xiao-Ping; Wang Zhen-Ming

    2012-01-01

    We investigated photoluminescence characteristics of silicone oils treated by C2F6 and CHF3 plasma.The silicone oil treated by the C2F6 plasma emitted a white light mainly composed of 415 nm,469 nm,and 554 nm emissions,while that treated by the CHF3 plasma emitted a pink light (415 nm).Fourier transformed infrared spectroscopy and Raman spectroscopy studies showed that the photoluminescence was correlated with the Si-C bond,the carbon-related defects and the oxygen vacancies.It was suggested that the light emitting at 554 nm was related to the Si-C bond and the carbon-related defects,while the pink emission at 415 nm was related to the oxygen vacancies.

  9. Preparation and Photoluminescence of ZnO Nanostructures

    Institute of Scientific and Technical Information of China (English)

    YAN Jin-Liang; ZHAO Yin-nu; SUN Xue-qing; GUO Chun

    2006-01-01

    Porous anodic alumina (PAA) hosts with ZnO nanoparticles loaded in were prepared by immersing PAA films in an aqueous solution of zinc acetate and then annealing at high temperatures. Highly ordered ZnO nanodot arrays were produced using the method in combination of PAA template with RF magnetron sputtering deposition. The photoluminescence of the ZnO/PAA composite and the highly ordered ZnO nanodot arrays were investigated by means of a fluorescent spectrometer. The ZnO/PAA composite exhibits intense and broad photoluminescence spectra with the peak position at around 485 nm. The ZnO nanodot arrays have a strong UV light emissive peak at about 380 nm and a wide light emissive peak at 460 nm-610 nm at the room temperature.

  10. The Photoluminescence Spectra of the Aeschynite Group Minerals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Raman and photoluminescence spectra of the metamict and annealing recrystallization titanoaeschynite-(Nd) and nioboaeschynite-(Ce), found in Baiyunobo mineral deposit in China, were measured and discussed. The peaks or bands in the spectra of the metamic minerals are weak, broad and diffuse, but sharpen notably after heating. The results show that the distortion of the structure and disorder state of the elements exists in the minerals when natural crystalline minerals transformed into metamict minerals after a long period of self-irradiation structure damaging. And all bands in the photoluminescence spectra of the aeschynite group mineral stem from emission transitions of Nd3+, when 514.5nm laser is used as the excitation source.

  11. Supercollision cooling effects on the hot photoluminescence emission of graphene.

    Science.gov (United States)

    Alencar, Thonimar V; Malard, Leandro M; Paula, Ana M de

    2016-09-30

    We report on hot photoluminescence measurements that show the effects of acoustic phonon supercollision processes in the intensity of graphene light emission. We use a simple optical method to induce defects on single layer graphene in a controlled manner to study in detail the light emission dependence on the sample defect density. It is now well accepted that the graphene photoluminescence is due to black-body thermal emission from the quasi-equilibrium electrons at a temperature well above the lattice temperature. Our results show that as the sample defect density is increased the electrons relax energy more efficiently via acoustic phonon supercollision processes leading to lower electron temperatures and thus lower emission intensities. The calculated intensity decrease due to supercollision energy relaxation agrees well with the experimental data.

  12. Macromolecularly "Caged" Carbon Nanoparticles for Intracellular Trafficking via Switchable Photoluminescence.

    Science.gov (United States)

    Misra, Santosh K; Srivastava, Indrajit; Tripathi, Indu; Daza, Enrique; Ostadhossein, Fatemeh; Pan, Dipanjan

    2017-02-08

    Reversible switching of photoluminescence (PL) of carbon nanoparticles (CNP) can be achieved with counterionic macromolecular caging and decaging at the nanoscale. A negatively charged uncoated, "bare" CNP with high luminescence loses its PL when positively charged macromolecules are wrapped around its surface. Prepared caged carbons could regain their emission only through interaction with anionic surfactant molecules, representing anionic amphiphiles of endocytic membranes. This process could be verified by gel electrophoresis, spectroscopically and in vitro confocal imaging studies. Results indicated for the first time that luminescence switchable CNPs can be synthesized for efficient intracellular tracking. This study further supports the origin of photoluminescence in CNP as a surface phenomenon correlated a function of characteristic charged macromolecules.

  13. Microscopic theory of spatially resolved photoluminescence in disordered nanostructures

    Directory of Open Access Journals (Sweden)

    Di Stefano, O

    2005-11-01

    Full Text Available Quantum dots have become objects of extensive research activity because of their applications such as advanced electronic and optoelectronic devices. Here we analyse theoretically the optical properties of dots naturally formed by interface fluctuations in GaAs narrow quantum wells. Specifically we present the simulations of local optical spectroscopy and spatially resolved photoluminescence in quantum wells with interface fluctuations. The theory includes light quantization, acoustic phonon scattering, and inhomogeneous sample-excitation and/or light-detection. Such theoretical framework provides a general basis for the description of spectroscopic imaging. Numerically calculated absorption and photoluminescence images clarify the impact of the near-field optical setup and put forward the potentials of the method for the understanding of near-field light emission from semiconductor quantum structures.

  14. Modulation of mixed-phase titania photoluminescence by oxygen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Pallotti, D.; Orabona, E.; Amoruso, S.; Maddalena, P. [Dipartimento di Fisica, Universitá degli Studi di Napoli “Federico II,” Via Cintia, I-80126 Napoli (Italy); Institute for Superconductors, Oxides and Innovative Materials and Devices, CNR-SPIN, U.O.S. Napoli, Via Cintia, I-80126 Napoli (Italy); Lettieri, S., E-mail: stefano.lettieri@spin.cnr.it [Institute for Superconductors, Oxides and Innovative Materials and Devices, CNR-SPIN, U.O.S. Napoli, Via Cintia, I-80126 Napoli (Italy)

    2014-07-21

    We investigate the effect of oxygen (O{sub 2}) adsorption on photoluminescence properties of mixed-phase titania nanoparticle films deposited by femtosecond pulsed laser deposition, aiming to assess preliminary conclusions about the feasibility of opto-chemical sensing based on titania. We evidence that O{sub 2} produces opposite responses in rutile and anatase photoluminescence efficiency, highlighting interesting potentialities for future double-parametric optical sensing based on titania. The results evidence an important role of lattice oxygen atoms, suggesting that the standard Schottky barrier mechanism driving the response toward gas species in most used metal-oxide sensors (e.g., tin dioxide) is not the only active mechanism in titania.

  15. Photoluminescence Imaging Characterization of Thin-Film InP

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Steve; Allende Motz, Alyssa; Moore, James; Zheng, Maxwell; Javey, Ali; Bermel, Peter

    2015-06-14

    Indium phosphide grown using a novel vapor-liquid-solid method is a promising low-cost material for III-V single-junction photovoltaics. In this work, we characterize the properties of these materials using photoluminescence (PL) imaging, time-resolved photoluminescence (TRPL), and microwave-reflection photoconductive decay (u-PCD). PL image data clearly shows the emergence of a self-similar dendritic growth network from nucleation sites, while zoomed-in images show grain structure and grain boundaries. Single photon TRPL data shows initial surface-dominated recombination, while two-photon excitation TRPL shows a lifetime of 10 ns. Bulk carrier lifetime may be as long as 35 ns as measured by u-PCD, which can be less sensitive to surface recombination.

  16. 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.

  17. Photoluminescence from narrow InAs-AlSb quantum wells

    Science.gov (United States)

    Brar, Berinder; Kroemer, Herbert; Ibbetson, James; English, John H.

    1993-01-01

    We report on photoluminescence spectra from narrow InAs-AlSb quantum wells. Strong, clearly resolved peaks for well widths from 2 to 8 monolayers were observed. Transmission electron micrographs show direct evidence for the structural quality of the quantum well structures. The transition energies of the narrowest wells suggest a strong influence of the AlSb X-barrier on the electronic states in the conduction band.

  18. Properties of Zn-doped GaN. I - Photoluminescence

    Science.gov (United States)

    Pankove, J. I.; Berkeyheiser, J. E.; Miller, E. A.

    1974-01-01

    It is shown that zinc in gallium nitride forms an efficient radiative center emitting blue light at 2.86 plus or minus 0.02 eV and acts as a deep acceptor that can render the crystal insulating. A systematic variation of growth conditions indicates that an optimization of the photoluminescence efficiency is possible. Under nonoptimal conditions lower photon energy emission is obtained.

  19. Photoluminescence of ion-implanted GaN

    Science.gov (United States)

    Pankove, J. I.; Hutchby, J. A.

    1976-01-01

    Thirty-five elements were implanted in GaN. Their photoluminescence spectra were measured and compared to those of an unimplanted control sample. Most impurities emit a peak at about 2.15 eV. Mg, Zn, Cd, Ca, As, Hg, and Ag have more characteristic emissions. Zn provides the most efficient recombination center. A set of midgap states is generated during the damage-annealing treatment.

  20. Quantum dot photoluminescence lifetime-based pH nanosensor.

    Science.gov (United States)

    Ruedas-Rama, Maria J; Orte, Angel; Hall, Elizabeth A H; Alvarez-Pez, Jose M; Talavera, Eva M

    2011-03-14

    The first CdSe/ZnS quantum dot photoluminescence lifetime-based pH nanosensor has been developed. The average lifetime of mercaptopropionic acid-capped QD nanosensors showed a linear response in the pH range of 5.2-6.9. These nanosensors have been satisfactorily applied for pH estimation in simulated intracellular media, with high sensitivity and high selectivity toward most of the intracellular components.

  1. High photoluminescence efficiency in polymer containing rare earth

    Institute of Scientific and Technical Information of China (English)

    Zhefu Wu; Qidan Ling; Xugang Shi; Jiangxin Zhang; Guangxin Zhu

    2005-01-01

    @@ Three novel kinds of polymers containing rare earth europium have been synthesized and the integrating sphere technique was employed to measure the absolute photoluminescence (PL) efficiency. The PL efficiencies were found to be up to about 40%, which indicates the potential usage in organic light emitting devices (OLED). The energy transfer from ligand to Eu ions and the 5D0 → 7F2 transition of Eu3+ were analyzed under the PL process.

  2. Red photoluminescence BCNO synthesized from graphene oxide nanosheets

    Science.gov (United States)

    Kang, Yue; Chu, Zeng-yong; Ma, Tian; Li, Wei-ping; Zhang, Dong-jiu; Tang, Xiao-yu

    2016-01-01

    In this paper, we demonstrate the conversion of graphene oxide (GO) into boron carbon oxynitride (BCNO) hybrid nanosheets via a reaction with boric acid and urea, during which the boron and nitrogen atoms are incorporated into graphene nanosheets. The experimental results reveal that GO is important for the photoluminescence (PL) BCNO phosphor particles. More importantly, in this system, the prepared BCNO phosphors can be used to prepare the materials needed for red light emitting diodes (LEDs).

  3. Electromodulation of photoluminescence in vacuum-evaporated films of bathocuproine

    Energy Technology Data Exchange (ETDEWEB)

    Misnik, Maciej; Falkowski, Karol [Department of Electronic Phenomena, Gdansk University of Technology, Narutowicza 11/12, 80-952 Gdansk (Poland); Mroz, Wojciech [Department of Electronic Phenomena, Gdansk University of Technology, Narutowicza 11/12, 80-952 Gdansk (Poland); Istituto per lo Studio delle Macromolecole (ISMAC), Consiglio Nazionale delle Ricerche (CNR), Via Bassini 15, 20133 Milano (Italy); OPTOTEC S.p.A., Via G. Zenale 44, 20024 Garbagnate Milanese (Italy); Stampor, Waldemar, E-mail: waldek@mif.pg.gda.pl [Department of Electronic Phenomena, Gdansk University of Technology, Narutowicza 11/12, 80-952 Gdansk (Poland)

    2013-01-02

    Highlights: Black-Right-Pointing-Pointer We report on optical properties of thin films of bathocuproine (BCP). Black-Right-Pointing-Pointer We apply electromodulation of photoluminescence (EML) spectroscopy. Black-Right-Pointing-Pointer The green photoluminescence band is attributed to the formation of dimers. Black-Right-Pointing-Pointer The EML quenching effect for dimers is due to exciton dissociation. Black-Right-Pointing-Pointer The EML results are explained in terms of the Onsager theory. -- Abstract: Electric field-modulated photoluminescence (EML) was measured in vacuum-evaporated films of bathocuproine (BCP), electron-transporting material commonly used in organic light-emitting diodes (OLEDs). The external electric field of 10{sup 6} V/cm strength decreases long-wavelength photoluminescence (PL) up to 10% but the same effect on short-wavelength PL is above one order of magnitude smaller. The distinctive difference between the EML characteristics for the short-wavelength (mono-molecular) and long-wavelength (associative species) emission of BCP films is a result of the different nature of relevant emissive states. Absorption, PL, EML and atomic force microscopy (AFM) measurements can be consistently explained assuming existence of dimer species in solid BCP with their population increasing during aging process of the films. Besides ground state absorption dimer states are assumed to be populated indirectly from molecular (Frenkel type) excitons diffusing to defected domains of the films where dissociate through an intermediate stage of geminate (e-h) pairs. The EML data are analyzed applying various models of (e-h) pair dissociation based on Poole-Frenkel, Braun, Onsager and Sano-Tachiya-Noolandi-Hong (STNH) theories. The Onsager theory explains satisfactorily the observed EML quenching effect for dimer-type PL. The Stark effect on fluorescence quantum yield should be possibly invoked to explain the EML characteristics of monomolecular emission of BCP.

  4. Composite Perovskites of Cesium Lead Bromide for Optimized Photoluminescence.

    Science.gov (United States)

    Ling, Yichuan; Tan, Lei; Wang, Xi; Zhou, Yan; Xin, Yan; Ma, Biwu; Hanson, Kenneth; Gao, Hanwei

    2017-07-20

    The halide perovskite CsPbBr3 has shown its promise for green light-emitting diodes. The optimal conditions of photoluminescence and the underlying photophysics, however, remain controversial. To address the inconsistency seen in the previous reports and to offer high-quality luminescent materials that can be readily integrated into functional devices with layered architecture, we created thin films of CsPbBr3/Cs4PbBr6 composites based on a dual-source vapor-deposition method. With the capability of tuning the material composition in a broad range, CsPbBr3 is identified as the only light emitter in the composites. Interestingly, the presence of the photoluminescence-inactive Cs4PbBr6 can significantly enhance the light emitting efficiency of the composites. The unique negative thermal quenching observed near the liquid nitrogen temperature indicates that a type of shallow state generated at the CsPbBr3/Cs4PbBr6 interfaces is responsible for the enhancement of photoluminescence.

  5. Ultraviolet-blue photoluminescence of ZnSe quantum dots.

    Science.gov (United States)

    Peng, Ling Ling; Wang, Yu Hua; Li, Cheng Yan

    2010-03-01

    Zinc blende, sphericity, monodisperse, high luminescence ZnSe quantum dots (QDs) were synthesized by a one-step mild hydrothermal route with Zn and Se dissolved in aqueous NaOH as the source material. The structure and the morphology of the sample were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that the products were cubic blende ZnSe ranging from 3.2 to 4.5 nm in size. TEM images showed that the QDs have very good dispersibility and distribution. The characteristic features of the absorption and photoluminescence spectra of ZnSe quantum dots were studied at room temperature. Compared with the bulk ZnSe, the absorption edges and luminescent peaks of ZnSe QDs were blue shifted to higher energies due to the quantum confinement effect. Photoluminescence at ultraviolet excitation showed the strong emission at 390 nm related to the higher excitonic states. ZnSe QDs exhibiting photoluminescence line widths as narrow as 40-60 nm. Meanwhile, we simply explored the theoretical mechanism of luminescence in ZnSe QDs and analogized the relation of various point defect concentrations of ZnSe.

  6. Quenching nitrogen-vacancy center photoluminescence with infrared pulsed laser

    CERN Document Server

    Lai, N D; Zheng, D; Jacques, V; Chang, H -C; Roch, J -F; Treussart, F

    2013-01-01

    Diamond nanocrystals containing Nitrogen-Vacancy (NV) color centers have been used in recent years as fluorescent probes for near-field and cellular imaging. In this work we report that an infrared (IR) pulsed excitation beam can quench the photoluminescence of NV color center in a diamond nanocrystal (size < 50 nm) with an extinction ratio as high as ~90%. We attribute this effect to the heating of the nanocrystal consecutive to multi-photon absorption by the diamond matrix. This quenching is reversible: the photoluminescence intensity goes back to its original value when the IR laser beam is turned off, with a typical response time of hundred picoseconds, allowing for a fast control of NV color center photoluminescence. We used this effect to achieve sub-diffraction limited imaging of fluorescent diamond nanocrystals on a coverglass. For that, as in Ground State Depletion super-resolution technique, we combined the green excitation laser beam with the control IR depleting one after shaping its intensity ...

  7. Gate-induced blueshift and quenching of photoluminescence in suspended single-walled carbon nanotubes

    OpenAIRE

    Yasukochi, S.; Murai, T.; Moritsubo, S.; Shimada, T.; Chiashi, S.; Maruyama, S.; Kato, Y. K.

    2011-01-01

    Gate-voltage effects on photoluminescence spectra of suspended single-walled carbon nanotubes are investigated. Photoluminescence microscopy and excitation spectroscopy are used to identify individual nanotubes and to determine their chiralities. Under an application of gate voltage, we observe slight blueshifts in the emission energy and strong quenching of photoluminescence. The blueshifts are similar for different chiralities investigated, suggesting extrinsic mechanisms. In addition, we f...

  8. Purchase of a Raman and Photoluminescence Imaging System for Characterization of Advanced Electrochemical and Electronic Materials

    Science.gov (United States)

    2016-01-05

    SECURITY CLASSIFICATION OF: Funds were used to purchase a Renishaw inVia Reflex Spectrometer System for Raman and Photoluminescence spectral...optics for spatial imaging, a temperature-controlled sample compartment, and photoluminescence imaging. The instrument is used by undergraduate...Unlimited UU UU UU UU 05-01-2016 15-Aug-2014 14-Aug-2015 Final Report: Purchase of a Raman and Photoluminescence Imaging System for Characterization of

  9. Photoluminescence from amino-containing polymer in the presence of CO2: carbamato anion formed as a fluorophore.

    Science.gov (United States)

    Pan, Xiaoyong; Wang, Guan; Lay, Chee Leng; Tan, Beng Hong; He, Chaobin; Liu, Ye

    2013-09-26

    Organic photoluminescent materials are important to many applications especially for diagnosis and detection, and most of organic photoluminescent materials contain fluorophores with extended conjugated structures. Recently some of amino-containing polymers without fluorophores with extended conjugated structure are observed to be photoluminescent, and one possible cause of the photoluminescence is oxidation of the amines. Here we show that photoluminescence can be produced by exposing a typical amino-containing polymer, polyethylenimine, to carbon dioxide. We demonstrate that carbamato anion formed via the reaction between the amine and carbon dioxide is a fluorophore; and the loosely-bound protonated water molecule can increase UV absorption but reduce the photoluminescence emission. Also carbamato anion shows solvent- and excitation wavelength-dependent emission of photoluminescence. The photoluminescence profile of carbamoto anion was discussed. These results will facilitate the understanding of photoluminescence observed from amino-containing materials and the design of new fluorophores.

  10. Quantum dots-nanogap metamaterials fabrication by self-assembly lithography and photoluminescence studies.

    Science.gov (United States)

    Tripathi, Laxmi Narayan; Kang, Taehee; Bahk, Young-Mi; Han, Sanghoon; Choi, Geunchang; Rhie, Jiyeah; Jeong, Jeeyoon; Kim, Dai-Sik

    2015-06-01

    We present a new and versatile technique of self-assembly lithography to fabricate a large scale Cadmium selenide quantum dots-silver nanogap metamaterials. After optical and electron microscopic characterizations of the metamaterials, we performed spatially resolved photoluminescence transmission measurements. We obtained highly quenched photoluminescence spectra compared to those from bare quantum dots film. We then quantified the quenching in terms of an average photoluminescence enhancement factor. A finite difference time domain simulation was performed to understand the role of an electric field enhancement in the nanogap over this quenching. Finally, we interpreted the mechanism of the photoluminescence quenching and proposed fabrication method of new metamaterials using our technique.

  11. 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.

  12. Synthesis of novel europium complexes and their photoluminescence properties

    Institute of Scientific and Technical Information of China (English)

    SHI Linfang; LI Yanwei; CAO Huaru; GUAN Ying; MA Yongchun

    2012-01-01

    Two novel luminescent Eu(Ⅲ) complexes with the formulas (NIP)Eu(DBM)3 1 and (ENIP)Eu(DBM)3 2 (NIP=2-(naphthalen-1-yl)-1H-imidazo [4,5-f] [1,10] phenanthroline,ENIP=1-ethy1-2-(naphthalen-1-yl)-1H-imidazo [4,5-)] [1,10] phenanthroline,DBM=dibenzoylmethanato) were successfully synthesized and characterized by IR and elemental analysis.The UV-vis absorption spectra and photoluminescence properties of the complexes were investigated,and the irradiation at the absorption band between 300-400 nm of europium complexes either in solution or in the solid state led to the emission of a sharp red band at ~610 nm,a characteristic Eu3+ emission due to the transition of5D0→7F2.Furthermore,the weak emission bands around 587 and 595 nm attributed to 5D0→7F0 and 5D0→7F1 transition were also displayed in the emission spectra.These results demonstrated that the Eu(Ⅲ) ion was sensitized efficiently by the ligand and displayed photoluminescence with high intensity,narrow half-peak width,and monochromic light.The excited-state lifetimes of 1 and 2 were in the microsecond time scale,but the photoluminescence quantum yield of 2 (0.03) was two times higher than that of 1 (0.01) which should be attributed to the effect of the ethyl substituting in ENIP.

  13. Quenching of porous silicon photoluminescence by deposition of metal adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Andsager, D.; Hilliard, J.; Hetrick, J.M.; AbuHassan, L.H.; Plisch, M.; Nayfeh, M.H. (Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States))

    1993-10-01

    Various metals were deposited on luminescent porous silicon (PS) by immersion in metal ion solutions and by evaporation. The photoluminescence (PL) was quenched upon immersion in ionic solutions of Cu, Ag, and Au but not noticeably quenched in other ionic solutions. Evaporation of 100 A of Cu or 110 A of Au was not observed to quench PL. Auger electron spectroscopy performed on samples quenched and then immediately removed from solution showed a metallic concentration in the PS layer of order 10 at.%, but persisting to a depth of order 3000 A.

  14. Enhancing and redirecting carbon nanotube photoluminescence by an optical antenna.

    Science.gov (United States)

    Böhmler, Miriam; Hartmann, Nicolai; Georgi, Carsten; Hennrich, Frank; Green, Alexander A; Hersam, Mark C; Hartschuh, Achim

    2010-08-02

    We observe the angular radiation pattern of single carbon nanotubes' photoluminescence in the back focal plane of a microscope objective and show that the emitting nanotube can be described by a single in-plane point dipole. The near-field interaction between a nanotube and an optical antenna modifies the radiation pattern that is now dominated by the antenna characteristics. We quantify the antenna induced excitation and radiation enhancement and show that the radiative rate enhancement is connected to a directional redistribution of the emission.

  15. Tuning Photoluminescence Response by Electric Field in Electrically Soft Ferroelectrics

    Science.gov (United States)

    Khatua, Dipak Kumar; Kalaskar, Abhijeet; Ranjan, Rajeev

    2016-03-01

    We show that an electrically soft ferroelectric host can be used to tune the photoluminescence (PL) response of rare-earth emitter ions by external electric field. The proof of this concept is demonstrated by changing the PL response of the Eu3 + ion by electric field on a model system Eu-doped 0.94 (Na1 /2Bi1 /2TiO3)-0.06 (BaTiO3) . We also show that new channels of radiative transitions, forbidden otherwise, open up due to positional disorder in the system, which can as well be tuned by electric field.

  16. Photoluminescence study on Eu-implanted GaN

    Institute of Scientific and Technical Information of China (English)

    Zhang Chun-Guang; Bian Liu-Fang; Chen Wei-De

    2005-01-01

    The photoluminescence (PL) properties of Eu-implanted GaN thin films are studied. The experimental results show that the PL intensity is seriously affected by ion implantation conditions. The PL efficiency increases exponentially with annealing temperature increasing up to a maximum temperature of 1050℃. Moreover, the PL intensity for the sample implanted along the channelling direction is nearly twice more than that observed from the sample implanted along the random direction. The thermal quenching of PL intensity from 10K to 300K for sample annealed at 1050℃ is only 42.%.

  17. Sensitized photoluminescence of erbium silicate synthesized on porous silicon framework

    Science.gov (United States)

    Shen, Hao; Xu, Lingbo; Li, Dongsheng; Yang, Deren

    2017-09-01

    Er silicate/porous silicon (PS) composites with effective sensitized erbium emission at 1.53 μm have been synthesized on the PS framework. Cross-sectional scanning electron microscopy and X-ray diffraction reveal that the PS is coated by Er silicate in composites. Indirect excitation of Er3+ ion luminescence via energy transfer from PS is confirmed. The temperature dependence of Er-related photoluminescence intensity and lifetime is investigated, which concludes a phonon-mediated energy transfer process. The combination of the PS framework and Er silicate provides a possible strategy for practical silicon-based light sources.

  18. Van Hove singularities and nonlinear photoluminescence in multiwalled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    YUAN Yan-hong; MIAO Run-cai; LIU Bao-ying

    2006-01-01

    The absorption spectrum and photoluminescence spectrum of multiwalled carbon nanotubes(MWNTs) and the peaks related with Van Hove singularities(VHS) were obtained experimentally.Both the VHS formation and the change of band gaps in MWNTs depend on the intershell interaction.The VHS makes the probability of optical transitions enhanced,but the intershell interaction suppresses such radiative transitions.The excitation in the experiment involves a two-photon absorption process and the emission light has the effect of the optical frequency up-conversion.

  19. Photoluminescence Study of Long Wavelength Superlattice Infrared Detectors

    Science.gov (United States)

    Hoglund, Linda; Khoshakhlagh, Arezou; Soibel, Alexander; Ting, David Z.; Hill, Cory J.; Keo, Sam; Gunapala, Sarath D.

    2011-01-01

    In this paper, the relation between the photoluminescence (PL) intensity and the PL peak wavelength was studied. A linear decrease of the PL intensity with increasing cut-off wavelength of long wavelength infrared CBIRDs was observed at 77 K and the trend remained unchanged in the temperature range 10 - 77 K. This relation between the PL intensity and the peak wavelength can be favorably used for comparison of the optical quality of samples with different PL peak wavelengths. A strong increase of the width of the PL spectrum in the studied temperature interval was observed, which was attributed to thermal broadening.

  20. Temperature-dependent photoluminescence of surface-engineered silicon nanocrystals

    Science.gov (United States)

    Mitra, Somak; Švrček, Vladimir; Macias-Montero, Manual; Velusamy, Tamilselvan; Mariotti, Davide

    2016-01-01

    In this work we report on temperature-dependent photoluminescence measurements (15–300 K), which have allowed probing radiative transitions and understanding of the appearance of various transitions. We further demonstrate that transitions associated with oxide in SiNCs show characteristic vibronic peaks that vary with surface characteristics. In particular we study differences and similarities between silicon nanocrystals (SiNCs) derived from porous silicon and SiNCs that were surface-treated using a radio-frequency (RF) microplasma system. PMID:27296771

  1. Measurement of Photoluminescence of Cu2O at 2 K

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu; ZHANG Gui-Zhong; XIANG Wang-Hua; KETTERSON J. B.

    2006-01-01

    @@ We present our measured photoluminescence of the quadrupolar transitions of the yellow series excitons of cuprous oxide at 2 K. By tuning the excitation energy in the two-photon quadrupolar absorption scheme of Cu2O, it is found that the band-gap value associated with this optical process can be characterized by a sharp resonance at 2.036eV at cryogenic temperature. This energy value is helpful to guide a proper excitation for creating cold excitonic gas in this crystal.

  2. Photoluminescence of spray pyrolysis deposited ZnO nanorods

    OpenAIRE

    Mikli Valdek; Kärber Erki; Raadik Taavi; Dedova Tatjana; Krustok Jüri; Mere Arvo; Krunks Malle

    2011-01-01

    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, ...

  3. Photoluminescence studies of single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1999-01-01

    Semiconductor quantum dots are considered a promising material system for future optical devices and quantum computers. We have studied the low-temperature photoluminescence properties of single InGaAs quantum dots embedded in GaAs. The high spatial resolution required for resolving single dots...... to resolve luminescence lines from individual quantum dots, revealing an atomic-like spectrum of sharp transition lines. A parameter of fundamental importance is the intrinsic linewidth of these transitions. Using high-resolution spectroscopy we have determined the linewidth and investigated its dependence...... on temperature, which gives information about how the exciton confined to the quantum dot interacts with the surrounding lattice....

  4. Strong photoluminescence emission from resonant Fibonacci quantum wells.

    Science.gov (United States)

    Chang, C H; Chen, C H; Hsueh, W J

    2013-06-17

    Strong photoluminescence (PL) emission from a resonant Fibonacci quantum well (FQW) is demonstrated. The maximum PL intensity in the FQW is significantly stronger than that in a periodic QW under the Bragg or anti-Bragg conditions. Moreover, the peaks of the squared electric field in the FQW are located very near each of the QWs. The optimal PL spectrum in the FQW has an asymmetrical form rather than the symmetrical one in the periodic case. The maximum PL intensity and the corresponding thickness filling factor in the FQW become greater with increasing generation order.

  5. Blue-shift photoluminescence from porous InAlAs

    Science.gov (United States)

    Jiang, Y. C.; Liu, F. Q.; Wang, L. J.; Yin, W.; Wang, Z. G.

    2010-11-01

    A porous InAlAs structure was first obtained by electrochemical etching. Nano-pore arrays were formed when the In0.52Al0.48As membrane was anodized at constant voltages in an HF aqueous solution. These self-assembled structures showed evident blue-shift photoluminescence emissions. While a quantum size effect alone underestimates the blue-shift energy for a sample with a relatively large average pore wall thickness, a novel effect caused by the asymmetric etching is proposed to account for this phenomenon. The results inferred from the x-ray double crystal diffraction are in good agreement with the experimental data.

  6. 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.

  7. TIME-RESOLVED PHOTOLUMINESCENCE OF SINTERED ZnO CERAMICS

    Institute of Scientific and Technical Information of China (English)

    WEN XIAO-MING(文小明); N.OHNO; ZHANG ZHONG-MING(张中明)

    2001-01-01

    The time-resolved photoluminescence (TRPL) of sintered ZnO ceramics was measured at low temperatures. A broad luminescence band was observed in the visible region. The TRPL experiment shows that photolurninescence decay behaviour can be depicted as t-π(r). The decay rate n(r) and lifetime are wavelength dependent, and the former varies exponentially with wavelength. The power-lowering behaviour of the luminescence intensity indicates that the luminescence band originates from the recombination of donor-acceptor pairs.

  8. Photoluminescence study of hydrogen donors in ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Herklotz, F., E-mail: frank.herklotz@physik.tu-dresden.d [Technische Universitaet Dresden, 01062 Dresden (Germany); Lavrov, E.V., E-mail: edward.lavrov@physik.tu-dresden.d [Technische Universitaet Dresden, 01062 Dresden (Germany); Weber, J. [Technische Universitaet Dresden, 01062 Dresden (Germany)

    2009-12-01

    A photoluminescence study of hydrogenated ZnO bulk crystals is presented. Two excitonic recombination lines at 3362.8 and 3360.1 meV are assigned to hydrogen shallow donors. Experimental evidence is presented that the corresponding donor to the line at 3362.8 meV, previously labeled I{sub 4}, originates from hydrogen trapped within the oxygen vacancy, H{sub O}. The line at 3360.1 meV was found to be due to hydrogen located at the bond-centered lattice site, H{sub BC}. The corresponding shallow donor has an ionization energy of 53 meV.

  9. Photoluminescence Property of Co3O4 Nanowires

    Institute of Scientific and Technical Information of China (English)

    XUE De-Sheng; GONG Yu; LIU Wen-Jing; SI Ming-Su; LIU Zai-Wen

    2007-01-01

    Co3O4 nanowire arrays are fabricated by electrodeposition with following heat-treatment in atmosphere ambient. Photoluminescence is investigated at 295 K. In the experiment, when increasing the excitation light wavelength from 260 nm to 360 nm, two kinds of emissions corresponding to the increasing excitation light wavelength are observed. One of them alters the excited emission position, another keeps its emission position. The distinct behaviour of excited emissions related to the increasing excitation wavelength indicates that the mechanism of them must be different. According to the experimental comparison and first-principle calculation, the two kinds of emissions are discussed.

  10. Photoluminescence and X-ray Diffraction of Distributed Bragg Reflector

    Institute of Scientific and Technical Information of China (English)

    LI Lin; LI Yong-da; LIU Wen-li; LU Bin; JU Guo-xian; ZHANG Yong-ming; HAO Yong-qin; SU Wei; ZHONG Jing-chang

    2004-01-01

    Spectral and structural characteristics of distributed Bragg reflector (DBR) in vertical-cavity surface-emitting lasers were studied with photoluminescence and double- crystal X- ray diffraction measurement. The expected high quality epitaxial DBR structure was verified. In the X- ray double- crystal rocking curves of DBR the zeroth- order peak, the first and second order satellite peaks were measured.Splitting of diffraction peak appeared in the rocking curves was analyzed. The effects of introduced deep energy levels on the structural perfection and optical properties were discussed.

  11. 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.

  12. Photoluminescent carbon dots from 1,4-addition polymers.

    Science.gov (United States)

    Jiang, Zhiqiang; Nolan, Andrew; Walton, Jeffrey G A; Lilienkampf, Annamaria; Zhang, Rong; Bradley, Mark

    2014-08-25

    Photoluminescent carbon dots were synthesised directly by thermopyrolysis of 1,4-addition polymers, allowing precise control of their properties. The effect of polymer composition on the properties of the carbon dots was investigated by TEM, IR, XPS, elemental analysis and fluorescence analysis, with carbon dots synthesised from nitrogen-containing polymers showing the highest fluorescence. The carbon dots with high nitrogen content were observed to have strong fluorescence in the visible region, and culture with cells showed that the carbon dots were non-cytotoxic and readily taken up by three different cell lines.

  13. Controlling carbon nanotube photoluminescence using silicon microring resonators

    CERN Document Server

    Noury, Adrien; Vivien, Laurent; Izard, Nicolas

    2015-01-01

    We report on coupling between semiconducting single-wall carbon nanotubes (s-SWNT) photoluminescence and silicon microring resonators. Polyfluorene extracted s-SWNT deposited on such resonators exhibit sharp emission peaks, due to interaction with the cavity modes of the microring resonators. Ring resonators with radius of 5 {\\mu}m and 10 {\\mu}m were used, reaching quality factors up to 4000 in emission. These are among the highest values reported for carbon nanotubes coupled with an integrated cavity on silicon platform, which open up the possibility to build s-SWNT based efficient light source on silicon.

  14. Photoluminescence intermittency of semiconductor quantum dots in dielectric environments

    Energy Technology Data Exchange (ETDEWEB)

    Isaac, A.

    2006-08-11

    The experimental studies presented in this thesis deal with the photoluminescence intermittency of semiconductor quantum dots in different dielectric environments. Detailed analysis of intermittency statistics from single capped CdSe/ZnS, uncapped CdSe and water dispersed CdSe/ZnS QDs in different matrices provide experimental evidence for the model of photoionization with a charge ejected into the surrounding matrix as the source of PL intermittency phenomenon. We propose a self-trapping model to explain the increase of dark state lifetimes with the dielectric constant of the matrix. (orig.)

  15. 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.

  16. 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.

  17. Photoluminescence in silicon implanted with silicon ions at amorphizing doses

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Kalyadin, A. E.; Kyutt, R. N.; Sakharov, V. I.; Serenkov, I. T.; Shek, E. I.; Afrosimov, V. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Tetel' baum, D. I. [Lobachevsky State University, Physicotechnical Research Institute (Russian Federation)

    2011-09-15

    Luminescent and structural properties of n-FZ-Si and n-Cz-Si implanted with Si ions at amorphizing doses and annealed at 1100 Degree-Sign C in a chlorine-containing atmosphere have been studied. An analysis of proton Rutherford backscattering spectra of implanted samples demonstrated that an amorphous layer is formed, and its position and thickness depend on the implantation dose. An X-ray diffraction analysis revealed that defects of the interstitial type are formed in the samples upon annealing. Photoluminescence spectra measured at 78 K and low excitation levels are dominated by the dislocation-related line D1, which is also observed at 300 K. The peak position of this line, its full width at half-maximum, and intensity depend on the conduction type of Si and implantation dose. As the luminescence excitation power is raised, a continuous band appears in the spectrum. A model is suggested that explains the fundamental aspects of the behavior of the photoluminescence spectra in relation to the experimental conditions.

  18. Micro-photoluminescence of single living diatom cells.

    Science.gov (United States)

    LeDuff, Paul; Roesijadi, Guritno; Rorrer, Gregory L

    2016-11-01

    Diatoms are single-celled microalgae that possess a nanostructured, porous biosilica shell called a frustule. This study characterized the micro-photoluminescence (μ-PL) emission of single living cells of the photosynthetic marine diatom Thalassiosira pseudonana in response to UV laser irradiation at 325 nm using a confocal Raman microscope. The photoluminescence (PL) spectrum had two primary peaks, one centered at 500-510 nm, which was attributed to the frustule biosilica, and a second peak at 680 nm, which was attributed to auto-fluorescence of photosynthetic pigments. The portion of the μ-PL emission spectrum associated with biosilica frustule in the single living diatom cell was similar to that from single biosilica frustules isolated from these diatom cells. The PL emission by the biosilica frustule in the living cell emerged only after cells were cultivated to silicon depletion. The discovery of the discovery of PL emission by the frustule biosilica within a single living diatom itself, not just its isolated frustule, opens up future possibilities for living biosensor applications, where the interaction of diatom cells with other molecules can be probed by μ-PL spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Temperature-dependent photoluminescence in light-emitting diodes

    Science.gov (United States)

    Lu, Taiping; Ma, Ziguang; Du, Chunhua; Fang, Yutao; Wu, Haiyan; Jiang, Yang; Wang, Lu; Dai, Longgui; Jia, Haiqiang; Liu, Wuming; Chen, Hong

    2014-01-01

    Temperature-dependent photoluminescence (TDPL), one of the most effective and powerful optical characterisation methods, is widely used to investigate carrier transport and localized states in semiconductor materials. Resonant excitation and non-resonant excitation are the two primary methods of researching this issue. In this study, the application ranges of the different excitation modes are confirmed by analysing the TDPL characteristics of GaN-based light-emitting diodes. For resonant excitation, the carriers are generated only in the quantum wells, and the TDPL features effectively reflect the intrinsic photoluminescence characteristics within the wells and offer certain advantages in characterising localized states and the quality of the wells. For non-resonant excitation, both the wells and barriers are excited, and the carriers that drift from the barriers can contribute to the luminescence under the driving force of the built-in field, which causes the existing equations to become inapplicable. Thus, non-resonant excitation is more suitable than resonant excitation for studying carrier transport dynamics and evaluating the internal quantum efficiency. The experimental technique described herein provides fundamental new insights into the selection of the most appropriate excitation mode for the experimental analysis of carrier transport and localized states in p-n junction devices. PMID:25139682

  20. Iodomethane-Mediated Organometal Halide Perovskite with Record Photoluminescence Lifetime.

    Science.gov (United States)

    Xu, Weidong; McLeod, John A; Yang, Yingguo; Wang, Yimeng; Wu, Zhongwei; Bai, Sai; Yuan, Zhongcheng; Song, Tao; Wang, Yusheng; Si, Junjie; Wang, Rongbin; Gao, Xingyu; Zhang, Xinping; Liu, Lijia; Sun, Baoquan

    2016-09-07

    Organometallic lead halide perovskites are excellent light harvesters for high-efficiency photovoltaic devices. However, as the key component in these devices, a perovskite thin film with good morphology and minimal trap states is still difficult to obtain. Herein we show that by incorporating a low boiling point alkyl halide such as iodomethane (CH3I) into the precursor solution, a perovskite (CH3NH3PbI3-xClx) film with improved grain size and orientation can be easily achieved. More importantly, these films exhibit a significantly reduced amount of trap states. Record photoluminescence lifetimes of more than 4 μs are achieved; these lifetimes are significantly longer than that of pristine CH3NH3PbI3-xClx films. Planar heterojunction solar cells incorporating these CH3I-mediated perovskites have demonstrated a dramatically increased power conversion efficiency compared to the ones using pristine CH3NH3PbI3-xClx. Photoluminescence, transient absorption, and microwave detected photoconductivity measurements all provide consistent evidence that CH3I addition increases the number of excitons generated and their diffusion length, both of which assist efficient carrier transport in the photovoltaic device. The simple incorporation of alkyl halide to enhance perovskite surface passivation introduces an important direction for future progress on high efficiency perovskite optoelectronic devices.

  1. Photoluminescence of localized excitons in InGan quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Usov, S. O., E-mail: S.Usov@mail.ioffe.ru; Tsatsul' nikov, A. F.; Lundin, V. V.; Sakharov, A. V.; Zavarin, E. E.; Ledentsov, N. N. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2008-02-15

    Photoluminescence spectra of samples with ultrathin InGaN layers embedded in AlGaN and GaN matrices are studied experimentally in the temperature range of 80 to 300 K. It is shown that the temperature dependences can be understood in the context of Eliseev's model and that, in the active region of the structures under study, the dispersion {sigma} of the exciton-localization energy depends on the average In content in InGaN-alloy layers. Furthermore, the Urbach energy E{sub U}, which characterizes the localization energy of excitons in the tails of the density of states, was determined from an analysis of the shape of the low-energy slope of the spectrum. It is shown that {sigma} and E{sub U}, quantities representing the scale of the exciton-localization effects, vary linearly with the photoluminescence-peak wavelength in the range from the ultraviolet to the green region of the spectrum.

  2. Photoluminescent colloidal Cu@C-NPs suspensions synthesized by LASL

    Science.gov (United States)

    Reyes-Contreras, D.; González-Aguilar, M. A.; Camacho-López, M. A.; Vigueras-Santiago, E.; Camacho-López, M.

    2017-05-01

    In this work we report the synthesis of photoluminescent carbon-coated copper nanoparticles (Cu@C-NPs) based colloidal suspensions, using the laser ablation of solids in liquids technique (LASL). LASL experiments were carried out by ablating a Cu solid target immersed in acetone as the liquid medium with ns-laser pulses (1064 nm) of a Nd-YAG laser. In all experiments the per pulse laser fluence and the repetition rate frequency were kept constant and the ablation time was varied. The as obtained Cu@C-NPs suspensions were optically characterized with absorption and photoluminescence spectroscopies. Raman spectroscopy was used to give evidence of the carbon shell deposited around the Cu NPs. TEM results showed that 10 nm spheroids Cu@C-NPs were obtained. The as obtained Cu@C-NPs suspensions displayed out a PL emission band similar to that for carbon nanoparticles suspensions obtained by the same technique. We have found that the blue-green PL emission band intensity is mainly dependent on the ablation and aging time of the samples. The Cu@C-NPs-based colloidal suspensions can be proposed as multifunctional due to its absorbance and emission properties.

  3. Near-unity photoluminescence quantum yield in MoS₂.

    Science.gov (United States)

    Amani, Matin; Lien, Der-Hsien; Kiriya, Daisuke; Xiao, Jun; Azcatl, Angelica; Noh, Jiyoung; Madhvapathy, Surabhi R; Addou, Rafik; KC, Santosh; Dubey, Madan; Cho, Kyeongjae; Wallace, Robert M; Lee, Si-Chen; He, Jr-Hau; Ager, Joel W; Zhang, Xiang; Yablonovitch, Eli; Javey, Ali

    2015-11-27

    Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure of merit, the room-temperature photoluminescence quantum yield (QY), is extremely low. The prototypical 2D material molybdenum disulfide (MoS2) is reported to have a maximum QY of 0.6%, which indicates a considerable defect density. Here we report on an air-stable, solution-based chemical treatment by an organic superacid, which uniformly enhances the photoluminescence and minority carrier lifetime of MoS2 monolayers by more than two orders of magnitude. The treatment eliminates defect-mediated nonradiative recombination, thus resulting in a final QY of more than 95%, with a longest-observed lifetime of 10.8 ± 0.6 nanoseconds. Our ability to obtain optoelectronic monolayers with near-perfect properties opens the door for the development of highly efficient light-emitting diodes, lasers, and solar cells based on 2D materials.

  4. Sonochemical Synthesis of Er3+-Doped ZnO Nanospheres with Enhanced Upconversion Photoluminescence

    OpenAIRE

    Jun Geng; Guang-Hui Song; Jun-Jie Zhu

    2012-01-01

    Er3+-doped ZnO nanospheres have been synthesized via a sonochemical conversion process. The formation mechanism of these nanocrystals is connected with the sonochemical effect of ultrasound irradiation. The as-prepared Er3+ doped ZnO nanospheres show enhanced photoluminescence and upconversion photoluminescence properties compared with pure ZnO.

  5. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  6. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    Science.gov (United States)

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  7. Investigation of temperature-dependent photoluminescence in multi-quantum wells.

    Science.gov (United States)

    Fang, Yutao; Wang, Lu; Sun, Qingling; Lu, Taiping; Deng, Zhen; Ma, Ziguang; Jiang, Yang; Jia, Haiqiang; Wang, Wenxin; Zhou, Junming; Chen, Hong

    2015-07-31

    Photoluminescence (PL) is a nondestructive and powerful method to investigate carrier recombination and transport characteristics in semiconductor materials. In this study, the temperature dependences of photoluminescence of GaAs-AlxGa1-xAs multi-quantum wells samples with and without p-n junction were measured under both resonant and non-resonant excitation modes. An obvious increase of photoluminescence(PL) intensity as the rising of temperature in low temperature range (T photoluminescence characters from the temperature dependence of integrated PL intensity unavailable. For resonant excitation, carriers are generated only in the wells and the temperature dependence of integrated PL intensity is very suitable to analysis the photoluminescence characters of quantum wells.

  8. Change energy photons of radiation, stimulating a photoluminescence in glasses and optical fiber, activated by bismuth

    CERN Document Server

    Ogluzdin, Valeriy E

    2011-01-01

    In the offered review ordering received and published by domestic and foreign researchers of the experimental results showing the phenomenon of a photoluminescence in glasses and optical fiber, activated by bismuth is executed, and from uniform positions representations about the process responsible for a photoluminescence in case of use for excitation of this environment of various laser sources are considered. At interpretation of process of a photoluminescence the known model considering mirror symmetry of features of frequency spectra of a photoluminescence (in this case the maximum values is used: humps or peaks of spectra of a photoluminescence) and the spectra characterising optical losses (absorption) of glass, activated by (atomic) bismuth. For the analysis values of lines of the bismuth, published in reference media are used. This model is added by earlier published specification of the author, according to which to a point of mirror symmetry of such spectra there corresponds frequency of radiation ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Xi, Yi [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Peng, Chen [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Wan, Buyong; He, Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)

    2011-06-15

    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: {yields} 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. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} 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{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}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{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non

  10. Photoluminescence Excitation Spectroscopy Characterization of Cadmium Telluride Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Moore, James E.; Wang, Xufeng; Grubbs, Elizabeth K.; Drayton, Jennifer; Johnston, Steve; Levi, Dean; Lundstrom, Mark S.; Bermel, Peter

    2016-11-21

    The use of steady-state photoluminescence spectroscopy as a contactless characterization tool, suitable for inline optical characterization, has been previously demonstrated for high efficiency solar cells such as GaAs. In this paper, we demonstrate the use of PLE characterization on a thin film CdS/CdTe np heterojunction solar cell, and compare the results to measured EQE and I-V data. In contrast to previous work on high-quality GaAs, the PLE and EQE spectra do not match closely here. We still find, however, that reliable material parameters can be extracted from the PLE measurements. We also provide a physical explanation of the limits defining the cases when the PLE and EQE spectra may be expected to match.

  11. Electrically tuned photoluminescence in large pitch cholesteric liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Middha, Manju, E-mail: kkraina@gmail.com; Kumar, Rishi, E-mail: kkraina@gmail.com; Raina, K. K., E-mail: kkraina@gmail.com [School of Physics and Materials Science, Thapar University, Patiala-147004, Punjab (India)

    2014-04-24

    Cholesteric liquid crystals are known as 1-D photonic band gap materials due to their periodic helical supramolecular structure and larger birefringence. Depending upon the helical twisted pitch length, they give the characteristic contrast due to selective Bragg reflections when viewed through the polarizing optical microscope and hence affect the electro-optic properties. So the optimization of chiral dopant concentration in nematic liquid crystal leads to control the transmission of polarized light through the microscope. Hence transmission based polarizing optical microscope is used for the characterization of helical pitch length in the optical texture. The unwinding of helical pitch was observed with the application of electric field which affects the intensity of photoluminescence.

  12. Photoluminescence studies of CdS layers for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gemain, Frederique; Robin, Ivan-Christophe; Renet, Sebastien; Bernardi, Sergio [Commissariat a l' Energie Atomique et aux Energies Alternatives, CEA-LETI, Minatec Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2012-08-15

    Photoluminescence (PL) measurements were performed on polycrystalline CdS films grown by close space sublimation (CSS) or by chemical bath deposition (CBD) in order to observe the evolution of emission features according to the deposition technique and post-deposition treatments. CdS is naturally n-type because of the presence of sulphur vacancies and in most of the observed samples, a donor-acceptor pair involving the sulfur vacancies could be identified at 1.65 eV. Different complexes emissions could be identified depending on the deposition technique and post-growth treatment. The best efficiencies were measured on CdTe/CdS based solar cells for which the CdS layer presents an excitonic donor bound PL peak as well as an emission corresponding to interstitial cadmium (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Photoluminescence Enhancement of Adsorbed Species on Si Nanoparticles.

    Science.gov (United States)

    Matsumoto, Taketoshi; Maeda, Masanori; Kobayashi, Hikaru

    2016-12-01

    We have fabricated Si nanoparticles from Si swarf using the beads milling method. The mode diameter of produced Si nanoparticles was between 4.8 and 5.2 nm. Si nanoparticles in hexane show photoluminescence (PL) spectra with peaks at 2.56, 2.73, 2.91, and 3.09 eV. The peaked PL spectra are attributed to the vibronic structure of adsorbed dimethylanthracene (DMA) impurity in hexane. The PL intensity of hexane with DMA increases by ~3000 times by adsorption on Si nanoparticles. The PL enhancement results from an increase in absorption probability of incident light by DMA caused by adsorption on the surface of Si nanoparticles.

  14. Photoluminescence enhancement through silicon implantation on SRO-LPCVD films

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Sanchez, A., E-mail: amorales@inaoep.mx [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico); Leyva, K.M.; Aceves, M. [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico); Barreto, J.; Dominguez, C. [Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Barcelona (Spain); Luna-Lopez, J.A.; Carrillo, J. [CIDS-BUAP, Apdo. 1651, Puebla 72000 (Mexico); Pedraza, J. [INAOE, Electronics Department, Apartado 51, Puebla 72000 (Mexico)

    2010-10-25

    Photoluminescence (PL) properties of thin and thick silicon-rich oxide (SRO) and silicon implanted SRO (SI-SRO) films with different silicon excess fabricated by low pressure chemical vapor deposition (LPCVD) were studied. The effects of the annealing temperature and silicon implantation on the PL were also studied. Maximum luminescence intensity was observed with an annealing temperature of 1150 and 1100 deg. C for thin and thick SRO films, respectively. The PL intensity is strongly enhanced when SRO films are implanted with silicon, especially for thin SRO films. Thin SI-SRO films emit up to six times more than non-implanted films, meanwhile the PL in thick SI-SRO films is only improved less than two times. Therefore, thin SI-SRO films are an interesting alternative for applications such as the fabrication of efficient Si-nps based LEDs.

  15. Photoluminescence dynamics in singlet fission chromophore liquid melts

    Science.gov (United States)

    Piland, Geoffrey B.; Bardeen, Christopher J.

    2017-02-01

    The effect of high temperature melting on the photophysics of three prototypical singlet fission molecules is investigated. Time-resolved photoluminescence is used to look at the melt phase of the molecules tetracene, diphenylhexatriene and rubrene. Chemical decomposition of tetracene precluded any detailed measurements on this molecule. In the diphenylhexatriene melt, a rapid singlet state nonradiative relaxation process outcompetes singlet fission. In the rubrene melt, singlet fission occurs at a rate similar to that of the crystal, but the decay of the delayed fluorescence is much more rapid. The rapid decay of the delayed fluorescence suggests that either the triplet lifetime is shortened, or the fusion probability decreases, or that both factors are operative at higher temperatures.

  16. Sharp and Bright Photoluminescence Emission of Single Crystalline Diacetylene Nanoparticles

    CERN Document Server

    Kima, Seokho; Kima, Hyeong Tae; Cuic, Chunzhi; Park, Dong Hyuk

    2016-01-01

    Amorphous nanoparticles (NPs) of diacetylene (DA) molecules were prepared by using a reprecipitation method. After crystallization through solvent-vapor annealing process, the highly crystalline DA NPs show different structural and optical characteristics compared with the amorphous DA NPs. The single crystal structure of DA NPs was confirmed by high-resolution transmission electron microscopy (HR-TEM) and wide angle X-ray scattering (WAXS). The luminescence color and photoluminescence (PL) characteristics of the DA NPs were measured using color charge-coupled device (CCD) images and high-resolution laser confocal microscope (LCM). The crystalline DA NPs emit bright green light emission compared with amorphous DA NPs and the main PL peak of the crystalline DA NPs exhibits relative narrow and blue shift phenomena due to enhanced interaction between DA molecular in the nano-size crystal structure.

  17. Surface characterization of InP using photoluminescence

    Science.gov (United States)

    Chang, R. R.; Iyer, R.; Lile, D. L.

    1987-01-01

    Photoluminescence (PL) measurements have been performed on InP samples in situ during various surface treatments including chemical etching, wet anodization, and low-pressure chemical vapor deposition. It was found, in agreement with previously published results, that the magnitude of the PL signal varies markedly with surface treatment due presumably to changes in either surface-state density, and/or surface potential. In an attempt to assess the effectiveness of this noninvasive method as a tool for characterizing and monitoring the progressive development of a semiconductor surface during processing, a number of experiments on InP have been performed. The results indicate that although some uncertainty may exist in assigning a mechanism for the PL change in any given experiment, the general trend appears to be that surface degradation results in a reduced signal. As a result, process steps which enhance the PL intensity are likely to be beneficial in the preparation of a high-quality interface.

  18. Plasmon mode excitation and photoluminescence enhancement on silver nanoring

    CERN Document Server

    Kuchmizhak, A A; Kulchin, Yu N; Vitrik, O B

    2015-01-01

    We demonstrate a simple and high-performance laser-assisted technique for silver nanoring fabrication, which includes the ablation of the Ag film by focused nanosecond pulses and subsequent reactive ion polishing. The nanoring diameter and thickness can be controlled by optimizing both the pulse energy and the metal film thickness at laser ablation step, while the subsequent reactive ion polishing provides the ability to fabricate the nanoring with desirable height. Scattering patterns of s-polarized collimated laser beam obliquely illuminating the nanoring demonstrate the focal spot inside the nanoring shifted from its center at a distance of ~ 0.57Rring. Five-fold enhancement of the photoluminescence signal from the Rhodamine 6G organic dye near the Ag nanoring was demonstrated. This enhancement was attributed to the increase of the electromagnetic field amplitude near the nanoring surface arising from excitation of the multipole plasmon modes traveling along the nanoring. This assumption was confirmed by d...

  19. A Thermal-Photovoltaic Device Based on Thermally Enhanced Photoluminescence

    CERN Document Server

    Manor, Assaf

    2015-01-01

    Single-junction photovoltaic cells are considered to be efficient solar energy converters, but even ideal cells cannot exceed the their fundamental thermodynamic efficiency limit, first analysed by Shockley and Queisser (SQ). For moderated irradiation levels, the efficiency limit ranges between 30%-40%. The efficiency loss is, to a great extent, due to the inherent heat-dissipation accompanying the process of electro-chemical potential generation. Concepts such as solar thermo-photovoltaics (STPV) and thermo-photonics4 aim to harness this dissipated heat, yet exceeding the SQ limit has not been achieved, mainly due to the very high operating temperatures needed. Recently, we demonstrated that in high-temperature endothermic-photoluminescence (PL), the photon rate is conserved with temperature increase, while each photon is blue shifted. We also demonstrated how endothermic-PL generates orders of magnitude more energetic-photons than thermal emission at similar temperatures. These new findings show that endoth...

  20. Photoluminescence structure, and composition of laterally anodized porous Si

    Science.gov (United States)

    Jung, K. H.; Shih, S.; Kwong, D. L.; George, T.; Lin, T. L.; Liu, H. Y.; Zavada, J.

    1992-01-01

    We have studied the photoluminescence (PL), structure, and composition of laterally anodized porous Si. Broad PL peaks were observed centered between about 620-720 nm with strong intensities measured from 500 to 860 nm. Macroscopic variations in PL intensities and peak positions are explained in terms of the structure and anodization process. Structural studies suggest that the PL appears to originate from a multilayered porous Si structure in which the top two layers are amorphous. X-ray diffraction spectra also suggest the presence of a significant amorphous phase. In addition to high concentrations of B and N, we have measured extremely high concentrations much greater than 10 exp 20 cu cm of H, C, O, and F. Our results indicate that laterally anodized porous Si does not fit the crystalline Si quantum wire model prevalent in the literature suggesting that some other structure is responsible for the observed luminescence.

  1. Synthesis and photoluminescence property of boron carbide nanowires

    Institute of Scientific and Technical Information of China (English)

    Bao Li-Hong; Li Chen; Tian Yuan; Tian Ji-Fa; Hui Chao; Wang Xing-Jun; Shen Cheng-Min; Gao Hong-Jun

    2008-01-01

    Large scale, high density boron carbide nanowires have been synthesized by using an improved carbothermal reduction method with B/B2O3/C powder precursors under an argon flow at 1100~C. The boron carbide nanowires are 5-10 μm in length and 80-100 nm in diameter. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) characterizations show that the boron carbide nanowire has a B4C rhombohedral structure with good crystallization. The Raman spectrum of the as-grown boron carbide nanowires is consistent with that of a B4C structure consisting of B11C icosahedra and C-B-C chains. The room temperature photoluminescence spectrum of the boron carbide nanowires exhibits a visible range of emission centred at 638 nm.

  2. Photoluminescence of ingaas/inp grown by molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Harmand Jean Christophe

    2004-01-01

    Full Text Available Photoluminescence (PL measurements due to temperature and excitation power were carried out in as function of sample containing a In0,53Ga0,47. As layer, grown by Molecular Beam Epitaxy on an InP substrate. The origins of the several luminescence processes observed at low temperature were determined by studying their different behaviors with increasing temperature and excitation power and by comparing the results with the data found in the literature. The following transitions have been identified: one transition involving localized excitons and two transitions involving acceptor impurities. A review of the main works published in the literature related to the optical transitions observed at low temperature in InGaAs/InP is also presented.

  3. Temperature Induced Stress Dependent Photoluminescence Properties of Nanocrystallite Zinc Oxide

    Directory of Open Access Journals (Sweden)

    V. Kumar

    2011-01-01

    Full Text Available In this paper, Temperature induced stress dependent structural, optical and photoluminescence properties of nanoscrysllites ZnO (nc-ZnO films are reported. It is seen that crystallite size, band gap and PL intensity of nc-ZnO are strongly dependent on stress. Large compressive stress has been observed at temperature 350-400 °C while minimum stress obtained at temperature 450 °C. A small amount of expensive stress is obtained at temperature 500 and 500 °C. The surface topography of the nc-ZnO films has been studied using atomic force microscopy. The optical band gap of nc-ZnO has been decreased from 3.25 to 3.23 eV as a function of temperature induced stress. The luminescence property is dependent on stress of nc-ZnO films.

  4. Photoluminescence study of Cu diffusion in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Grecu, D.; Compaan, A.D. [Department of Physics, University of Toledo, Toledo, Ohio (United States)

    1999-03-01

    We report changes in the photoluminescence spectra associated with the diffusion of Cu in CdTe thin films used in CdTe/CdS solar cells. Films grown by vapor transport deposition and radio-frequency sputtering as well as single crystal CdTe were included in the study. The main effects of Cu diffusion appear to be the quenching of a donor-acceptor transition associated with Cd vacancies and the increase in intensity of a lower energy broad-band transition. The PL is subsequently used to explore the effects of electric fields on Cu diffusion. The role of Te as a diffusion barrier for Cu is investigated. {copyright} {ital 1999 American Institute of Physics.}

  5. 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.

  6. Note: Photoluminescence measurement system for multi-junction solar cells.

    Science.gov (United States)

    Trespidi, F; Malchiodi, A; Farina, F

    2017-05-01

    We describe a photoluminescence spectroscopy system developed for studying phenomena of optical coupling in multiple-junction solar cells and processed/unprocessed wafers, under the high solar concentration levels typical of HCPV (High Concentration PhotoVoltaic) systems. The instrument operates at room temperature over two spectral ranges: 475 nm-1100 nm and 950 nm-1650 nm. Power densities exceeding 10 000 suns can be obtained on the sample. The system can host up to four compact focusable solid state laser sources, presently only three are mounted and operated at 450 nm, 520 nm, and 785 nm; they provide overlapped beams on the sample surface and can shine simultaneously the sample to study possible mutual interaction between the different junctions.

  7. Shell-Controlled Photoluminescence in CdSe/CNT Nanohybrids

    Directory of Open Access Journals (Sweden)

    Si Hua-Yan

    2009-01-01

    Full Text Available Abstract A new type of nanohybrids containing carbon nanotubes (CNTs and CdSe quantum dots (QDs was prepared using an electrostatic self-assembly method. The CdSe QDs were capped by various mercaptocarboxylic acids, including thioglycolic acid (TGA, dihydrolipoic acid (DHLA and mercaptoundecanoic acid (MUA, which provide shell thicknesses of ~5.2, 10.6 and 15.2 Å, respectively. The surface-modified CdSe QDs are then self-assembled onto aridine orange-modified CNTs via electrostatic interaction to give CdSe/CNT nanohybrids. The photoluminescence (PL efficiencies of the obtained nanohybrids increase significantly with the increase of the shell thickness, which is attributed to a distance-dependent photo-induced charge-transfer mechanism. This work demonstrates a simple mean for fine tuning the PL properties of the CdSe/CNT nanohybrids and gains new insights to the photo-induced charge transfer in such nanostructures.

  8. Photoluminescent carbon nanodots: synthesis, physicochemical properties and analytical applications

    Directory of Open Access Journals (Sweden)

    Prathik Roy

    2015-10-01

    Full Text Available Carbon nanodots (C-dots possessing photoluminescence (PL properties have become interesting materials for sensing and imaging, with the advantages of water-dispersibility, biocompatibility, chemical and photo stability. They can be prepared from organic matter such as tea, grass, coffee, and small organic molecules like glycine and glucose through hydrothermal routes. In this review, we focus on the recent advances in the synthesis and characterization of C-dots along with their optical (absorption, PL, upconverted PL properties and analytical applications. Having bright PL, biocompatibility, chemical and photo stability, as well as low toxicity, C-dots have been used for the detection of metal ions and for cell imaging. C-dots prepared from organic matter such as used tea and ginger possess a great inhibitory effect on the growth of cancer cells, showing their excellent potential as new drugs.

  9. Enhanced Photoluminescence Property for Quantum Dot-Gold Nanoparticle Hybrid

    Science.gov (United States)

    Huang, Qianqian; Chen, Jing; Zhao, Jian; Pan, Jiangyong; Lei, Wei; Zhang, Zichen

    2015-10-01

    In this paper, we have synthesized ZnCdSeS quantum dots (QDs)-gold nanoparticle (Au NPs) hybrids in aqueous solution via bi-functional linker mercaptoacetic acid (MPA). The absorption peaks of ZnCdSeS QDs and Au are both located at 520 nm. It is investigated that PL intensity of QD-Au hybrid can be affected by the amounts of Au and pH value of hybrid solution. The located surface plasmon resonance (LSPR) effect of QD-Au NPs has been demonstrated by increased fluorescence intensity. The phenomenon of fluorescence enhancement can be maximized under the optimized pH value of 8.5. LSPR-enhanced photoluminescence property of QD-Au hybrid will be beneficial for the potential applications in the area of biological imaging and detection.

  10. The photoluminescence properties of zinc oxide nanofibres prepared by electrospinning

    Science.gov (United States)

    Viswanathamurthi, Periasamy; Bhattarai, Narayan; Kim, Hak Yong; Lee, Douk Rae

    2004-03-01

    The morphology and optical properties of zinc oxide fibres with diameters in the nanometre to micrometre range are reported. The PVA/zinc acetate organic/inorganic hybrid nanofibres were successfully prepared by electrospinning using polyvinyl alcohol (PVA) and zinc acetate. Pure zinc oxide fibres were obtained by high-temperature calcination of the hybrid fibres in air. The nanofibres were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffractometry (XRD) and Raman spectroscopy. The photoluminescence spectra under excitation at 325 nm showed an ultraviolet emission at 3.13 eV and a green emission at 2.21 eV. These nanofibres could be used as light emitting devices in nanoscale optoelectronic applications.

  11. Red Mechanoluminescence and Photoluminescence from Novel Europium Complexes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two new binuclear (europium and lanthanum) b -diketone complexes Eu0.9La0.1(TTA)3Phen and Eu0.5La0.5(TTA)3Phen in which Phen is 1,10-phenanthroline, TTA is an anion of thenoyltrifluoroacetone (HTTA) were synthesized for the first time. They showed intense photoluminescence (PL) and mechanoluminescence (ML), and had their maximum PL and ML spectra peaked at 613.5 nm with half bandwidth of 10 nm respectively. Their PL and ML intensity were obviously stronger than these from Eu(TTA)3Phen. It is considered that binuclear (europium and lanthanum) b -diketones complexes are promising ML and PL materials.

  12. Photoluminescence in large fluence radiation irradiated space silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hisamatsu, Tadashi; Kawasaki, Osamu; Matsuda, Sumio [National Space Development Agency of Japan, Tsukuba, Ibaraki (Japan). Tsukuba Space Center; Tsukamoto, Kazuyoshi

    1997-03-01

    Photoluminescence spectroscopy measurements were carried out for silicon 50{mu}m BSFR space solar cells irradiated with 1MeV electrons with a fluence exceeding 1 x 10{sup 16} e/cm{sup 2} and 10MeV protons with a fluence exceeding 1 x 10{sup 13} p/cm{sup 2}. The results were compared with the previous result performed in a relative low fluence region, and the radiation-induced defects which cause anomalous degradation of the cell performance in such large fluence regions were discussed. As far as we know, this is the first report which presents the PL measurement results at 4.2K of the large fluence radiation irradiated silicon solar cells. (author)

  13. 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.

  14. Growth orientation dependent photoluminescence of GaAsN alloys

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xiuxun; Tanaka, Tomohiro; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan); Sato, Shinichiro [Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2012-01-16

    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.

  15. Photoluminescence-enhanced plasmonic substrates fabricated by nanoimprint lithography

    Science.gov (United States)

    Choi, Bongseok; Iwanaga, Masanobu; Miyazaki, Hideki T.; Sakoda, Kazuaki; Sugimoto, Yoshimasa

    2014-04-01

    We fabricated large-area stacked complementary plasmonic crystals (SC PlCs) by employing ultraviolet nanoimprint lithography. The SC PlCs were made on silicon-on-insulator substrates consisting of three layers: the top layer contacting air was a perforated Au film, the bottom layer contacting the buried oxide layer included an Au disk array corresponding to the holes in the top layer, and the middle layer was a Si photonic crystal slab. The SC PlCs have prominent resonances in optical wavelengths. It is shown that the fabricated PlCs were precise in structure and uniform in their optical properties. We examined the photoluminescence (PL) enhancement of monolayer dye molecules on the SC PlC substrates in the visible range and found large PL enhancements of up to a 100-fold in comparison with dye molecules on nonprocessed Si wafers.

  16. 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.

  17. Carbon Dot Nanothermometry: Intracellular Photoluminescence Lifetime Thermal Sensing.

    Science.gov (United States)

    Kalytchuk, Sergii; Poláková, Kateřina; Wang, Yu; Froning, Jens P; Cepe, Klara; Rogach, Andrey L; Zbořil, Radek

    2017-02-28

    Nanoscale biocompatible photoluminescence (PL) thermometers that can be used to accurately and reliably monitor intracellular temperatures have many potential applications in biology and medicine. Ideally, such nanothermometers should be functional at physiological pH across a wide range of ionic strengths, probe concentrations, and local environments. Here, we show that water-soluble N,S-co-doped carbon dots (CDs) exhibit temperature-dependent photoluminescence lifetimes and can serve as highly sensitive and reliable intracellular nanothermometers. PL intensity measurements indicate that these CDs have many advantages over alternative semiconductor- and CD-based nanoscale temperature sensors. Importantly, their PL lifetimes remain constant over wide ranges of pH values (5-12), CD concentrations (1.5 × 10(-5) to 0.5 mg/mL), and environmental ionic strengths (up to 0.7 mol·L(-1) NaCl). Moreover, they are biocompatible and nontoxic, as demonstrated by cell viability and flow cytometry analyses using NIH/3T3 and HeLa cell lines. N,S-CD thermal sensors also exhibit good water dispersibility, superior photo- and thermostability, extraordinary environment and concentration independence, high storage stability, and reusability-their PL decay curves at temperatures between 15 and 45 °C remained unchanged over seven sequential experiments. In vitro PL lifetime-based temperature sensing performed with human cervical cancer HeLa cells demonstrated the great potential of these nanosensors in biomedicine. Overall, N,S-doped CDs exhibit excitation-independent emission with strongly temperature-dependent monoexponential decay, making them suitable for both in vitro and in vivo luminescence lifetime thermometry.

  18. Development of micromarkers with various photoluminescence colors as tracers for shadowing pursuits.

    Science.gov (United States)

    Kurata, Shoji; Hirano, Haruo; Nagai, Masatoshi

    2008-02-01

    Micromarkers with five photoluminescence colors were developed as tracers for shadowing pursuits. The markers are colorless powders with particle diameters of several tens to several hundreds of micrometers, prepared using a cryogenic sample crusher. They were visualized using red, green, yellow, magenta or cyan photoluminescence under ultraviolet light at approximately 365 nm. The markers were composed of photoluminescent compounds dispersed in polyvinyl butyral. The photoluminescent compounds in the polyvinyl butyral were stable under ambient conditions for more than one year after application. The compounds with the red, green, yellow, magenta and cyan photoluminescence contained a europium (Eu(3+)) complex, a terbium (Tb(3+)) complex, a mixture of Tb(3+) and Eu(3+) complexes, a mixture of Eu(3+) complex and o-coumaric acid, and a mixture of Tb(3+) complex and 7-hydroxycoumarin along with a few drops of a sodium bicarbonate aqueous solution, respectively. Neodymium (Nd(3+)) and ytterbium (Yb(3+)) complexes with photoluminescence in the near-IR wavelength region can also be added to these visible photoluminescent compounds as secret markers for discrimination. The markers were non-destructively identified using a microscopic FT-IR spectrometer and a microscopic spectrometer equipped with a fluorescence detector.

  19. Correlation of atomic structure and photoluminescence of the same quantum dot: pinpointing surface and internal defects that inhibit photoluminescence.

    Science.gov (United States)

    Orfield, Noah J; McBride, James R; Keene, Joseph D; Davis, Lloyd M; Rosenthal, Sandra J

    2015-01-27

    In a size regime where every atom counts, rational design and synthesis of optimal nanostructures demands direct interrogation of the effects of structural divergence of individuals on the ensemble-averaged property. To this end, we have explored the structure-function relationship of single quantum dots (QDs) via precise observation of the impact of atomic arrangement on QD fluorescence. Utilizing wide-field fluorescence microscopy and atomic number contrast scanning transmission electron microscopy (Z-STEM), we have achieved correlation of photoluminescence (PL) data and atomic-level structural information from individual colloidal QDs. This investigation of CdSe/CdS core/shell QDs has enabled exploration of the fine structural factors necessary to control QD PL. Additionally, we have identified specific morphological and structural anomalies, in the form of internal and surface defects, that consistently vitiate QD PL.

  20. Photoluminescence and Raman Spectroscopy Characterization of Boron- and Nitrogen-Doped 6H Silicon Carbide

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Liu, Chuan

    2012-01-01

    Nitrogen-boron doped 6H-SiC epilayers grown on low off-axis 6H-SiC substrates have been characterized by photoluminescence and Raman spectroscopy. The photoluminescence results show that a doping larger than 1018 cm-3 is favorable to observe the luminescence and addition of nitrogen is resulting...... in an increased luminescence. A dopant concentration difference larger than 4x1018 cm-3 is proposed to achieve intense photoluminescence. Raman spectroscopy further confirmed the doping type and concentrations for the samples. The results indicate that N-B doped SiC is being a good wavelength converter in white...

  1. Use of a gold reflecting-layer in optical antenna substrates for increase of photoluminescence enhancement.

    Science.gov (United States)

    Fernandez-Garcia, Roberto; Rahmani, Mohsen; Hong, Minghui; Maier, Stefan A; Sonnefraud, Yannick

    2013-05-20

    We report on a straightforward way to increase the photoluminescence enhancement of nanoemitters induced by optical nanotantennas. The nanoantennas are placed above a gold film-silica bilayer, which produces a drastic increase of the scattered radiation power and near field enhancement. We demonstrate this increase via photoluminescence enhancement using an organic emitter of low quantum efficiency, Tetraphenylporphyrin (TPP). An increase of the photoluminescence enhancement by a factor larger than three is observed compared to antennas without the reflecting-layer. In addition, we study the possibility of influencing the polarization of the light emitted by utilizing asymmetry of dimer antennas.

  2. Near-infrared anti-Stokes photoluminescence of PbS QDs embedded in glasses.

    Science.gov (United States)

    Xiong, Yuda; Liu, Chao; Wang, Jing; Han, Jianjun; Zhao, Xiujian

    2017-03-20

    Near-infrared photoluminescence properties of PbS QDs embedded in glasses were investigated upon below-bandgap excitation. PbS QDs were precipitated in the glasses upon thermal treatment. Near-infrared anti-Stokes photoluminescence (ASPL) from PbS QDs was observed. Dependence of the ASPL on size and excitation power indicated that ASPL was phonon-assisted one-photon process. These near-infrared anti-Stokes photoluminescence of PbS QDs in glasses have potential applications for light conversion and laser cooling.

  3. 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

  4. Relationship between the electric performance and the photoluminescence spectra of resonant tunnelling diodes

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiao-Xin; Zeng Yi-Ping; Wang Xiao-Guang; Wang Bao-Qiang; Zhu Zhan-Ping

    2004-01-01

    Resonant tunnelling diodes with different structures were grown. Their photoluminescence spectra were investigated. By contrast, the luminescence in the quantum well is separated from that of other epilayers. The result is obtained that the exciton of the luminescence in the quantum well is partly come from the cap layer in the experiment.So the photoluminescence spectrum is closely related to the electron transport in the resonant tunnelling diode structure.This offers a method by which the important performance of resonant tunnelling diode could be forecast by analysing the integrated photoluminescence intensities.

  5. New Photoluminescence Phenomena of Ge/SiO2 Glass Synthesized by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    Yu Ying FENG; Xiao Tian GU; Jia Hong ZHOU; Jian Chun BAO; Gang LI; Tian Hong LU

    2004-01-01

    New Ge/SiO2 glasses have been synthesized by heating the GeO2/SiO2 dry gels under H2 gas at 700℃. The resulting fluorescence spectra show that this kind of Ge/SiO2 glasses emit strong photoluminescence at 392 nm (3.12 eV), medium strong photoluminescence at 600 nm (2.05 eV)and weak photoluminescence at 770 nm (1.60 eV) respectively. Possible photolnminescence mechanisms are also discussed based on the results of X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS).

  6. Enhancement of Photoluminescence Lifetime of ZnO Nanorods Making Use of Thiourea

    OpenAIRE

    Erdal Sönmez; Kadem Meral

    2012-01-01

    We have investigated correlation of photoluminescence lifetime between zinc oxide (ZnO) nanorods and thiourea-doped ZnO nanorods (tu: CH4N2S). Aqueous solutions of ZnO nanorods were deposited on glass substrate by using pneumatic spray pyrolysis technique. The as-prepared specimens were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and time-resolved photoluminescence spectroscopy (TRPL). The photoluminescence lifetime of ZnO nanorods and ZnO nanorods containing...

  7. Compositional and photoluminescent properties of anodically and stain etched porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Lemus, R.; Hernandez-Rodriguez, C. [Laboratorio de Optica, Departamento de Fisica Basica, Universidad de La Laguna, 38204 S/C de Tenerife (Spain); Ben-Hander, F.A.; Martinez-Duart, J.M. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, Consejo Superior de Investigaciones Cientificas (CSIC), Cantoblanco, 28049 Madrid (Spain)

    2003-05-01

    A comparison of the compositional and photoluminescent properties of stain etched (SE) and anodically etched (AE) porous silicon (PS) samples has been carried out. The silicon substrates used and the laboratory conditions are the same for both types of etching processes. The study is carried out varying the PS surface properties by means of different cleaning procedures and post-etching ambient conditions. The results demonstrate that the evolution of the photoluminescence and the composition are related for both types of PS (AE and SE). Thus, it seems highly likely that the photoluminescence mechanisms involved in both cases are similar. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  8. Photoluminescence Characterization of Boron-doped Si Layers Grown by Molecular Beam Epitaxy

    Institute of Scientific and Technical Information of China (English)

    LI Cheng; LAI Hong-kai; CHEN Song-yan

    2005-01-01

    Photoluminescence spectra were used to characterize the boron-doped Si layers grown by molecular beam epitaxy using HBO2 as the doping source. The influence of boron doping concentration on the dislocation-related photoluminescence spectra of molecular beam epitaxy Si layers annealed at 900 ℃ was studied with different doping concentrations and growth temperature. The broad photoluminescence band(from 0.75 eV to 0.90 eV) including D1 and D2 bands was associated with high boron doping concentration in the samples, while D3 and D4 bands might be related to oxygen precipitates.

  9. Theoretical and experimental analysis of the photoluminescence and photoluminescence excitation spectroscopy spectra of m-plane InGaN/GaN quantum wells

    Science.gov (United States)

    Schulz, S.; Tanner, D. S. P.; O'Reilly, E. P.; Caro, M. A.; Tang, F.; Griffiths, J. T.; Oehler, F.; Kappers, M. J.; Oliver, R. A.; Humphreys, C. J.; Sutherland, D.; Davies, M. J.; Dawson, P.

    2016-11-01

    We present a combined theoretical and experimental analysis of the optical properties of m-plane InGaN/GaN quantum wells. The sample was studied by photoluminescence and photoluminescence excitation spectroscopy at low temperature. The spectra show a large Stokes shift between the lowest exciton peak in the excitation spectra and the peak of the photoluminescence spectrum. This behavior is indicative of strong carrier localization effects. These experimental results are complemented by tight-binding calculations, accounting for random alloy fluctuations and Coulomb effects. The theoretical data explain the main features of the experimental spectra. Moreover, by comparison with calculations based on a virtual crystal approximation, the importance of carrier localization effects due to random alloy fluctuations is explicitly shown.

  10. Enantioselective silver nanoclusters: Preparation, characterization and photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Farrag, Mostafa, E-mail: mostafafarrag@aun.edu.eg

    2016-09-01

    Herein, we report a new wet-synthesis method to separate some water-soluble chiral silver nanoclusters with high yield. The cluster material was obtained by the reduction of silver nitrate with NaBH{sub 4} in the presence of three ligands L-penicillamine (L-pen), D-penicillamine (D-pen) and racemic mixture of penicillamine (rac-pen), functioning as capping ligand. For characterizing all silver cluster samples, the particle size was assessed by transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) and their average chemical formula was determined from thermogravimetric analysis (TGA) and elemental analysis (EA). The particles sizes of all three clusters are 2.1 ± 0.2 nm. The optical properties of the samples were studied by four different methods: UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL) and circular dichroism (CD) spectroscopy. The spectra are dominated by the typical and intense plasmon peak at 486 nm accompanied by a small shoulder at 540 nm. Infrared spectroscopy was measured for the free ligand and protected silver nanoclusters, where the disappearance of the S-H vibrational band (2535–2570 cm{sup −1}) in the silver nanoclusters confirmed anchoring of ligand to the cluster surface through the sulfur atom. PL studies yielded the fluorescent properties of the samples. The main focus of this work, however, lies in the chirality of the particles. For all silver clusters CD spectra were recorded. While for clusters capped with one of the two enantiomers (D- or L-form) typical CD spectra were observed, no significant signals were detected for a racemic ligand mixture. Furthermore, silver clusters show quite large asymmetry factors (up to 3 × 10{sup −4}) in comparison to most other ligand protected clusters. These large factors and bands in the visible range of the spectrum suggest a strong chiral induction from the ligand to the metal core. Textural features of the

  11. Microcrystalline silicon films and solar cells investigatet by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merdzhanova, T.

    2005-07-01

    A systematic investigation on photoluminescence (PL) properties of microcrystalline silicon ({mu}c-Si:H) films with structural composition changing from highly crystalline to predominantly amorphous is presented. The samples were prepared by PECVD and HWCVD with different silane concentration in hydrogen (SC). By using photoluminescence in combination with Raman spectroscopy the relationship between electronic properties and the microstructure of the material is studied. The PL spectra of {mu}c-Si:H reveal a rather broad ({proportional_to}0.13 eV) featureless band at about 1 eV ('{mu}c'-Si-band). In mixed phase material of crystalline and amorphous regions, a band at about 1.3 eV with halfwidth of about 0.3 eV is found in addition to '{mu}c'-Si-band, which is attributed to the amorphous phase ('a'-Si-band). Similarly to amorphous silicon, the '{mu}c'-Si-band is assigned to recombination between electrons and holes in band tail states. An additional PL band centred at about 0.7 eV with halfwidth slightly broader than the '{mu}c'-Si-band is observed only for films prepared at high substrate temperature and it is preliminarily assigned to defect-related transitions as in polycrystalline silicon. With decreasing crystalline volume fraction, the '{mu}c'-Si-band shifts continuously to higher energies for all {mu}c-Si:H films but the linewidth of the PL spectra is almost unaffected. This is valid for all deposition conditions investigated. The results are interpreted, assuming decrease of the density of band tail states with decreasing crystalline volume fraction. A simple model is proposed to simulate PL spectra and V{sub oc} in {mu}c-Si:H solar cells as a function of temperature, based on carrier distributions in quasi-equilibrium conditions. In the model is assumed symmetric density of states distributions for electrons and holes in the conduction and the valence band tail states. The best agreement between

  12. Conical bubble photoluminescence from rhodamine 6G in 1, 2-propanediol

    Institute of Scientific and Technical Information of China (English)

    He Shou-Jie; Ai Xi-Cheng; Dong Li-Fang; Chen De-Ying; Wang Qi; Li Xue-Chen; Zhang Jian-Ping; Wang Long

    2006-01-01

    A modified U-tube conical bubble sonoluminescence device is used to study the conical bubble photoluminescence.The spectra of conical bubble sonoluminescence at different concentrations of rhodamine 6G (Rh6G) solution in 1,2-propanediol have been measured. Results show that the sonoluminescence from the conical bubbles can directly excite Rh6G, which in turn can fluoresce. The light emission of this kind is referred to as conical bubble photoluminescence.The maximum of fluorescence spectral line intensity in the conical bubble photoluminescence has a red shift in relative to that of the standard photo-excited fluorescence, which is due to the higher self-absorption of Rh6G, and the spectral line of conical bubble photoluminescence is broadened in width compared with that of photo-excited fluorescence.

  13. INFRARED PHOTOLUMINESCENCE SPECTRA OF PBS NANOPARTICLES PREPARED BY LANGMUIR–BLODGETT AND LASER ABLATION METHODS

    Directory of Open Access Journals (Sweden)

    Zdeněk Remes

    2014-12-01

    Full Text Available We optimized the optical setup originally designed for the photoluminescence measurements in the spectral range 400‒1100 nm. New design extends the spectral range into the near infrared region 900‒1700 nm and allows the colloidal solutions measurements in cuvettes as well as the measurements of nanoparticles deposited in the form of thin films on glass substrates. The infrared photoluminescence spectra of the PbS nanoparticles prepared by the Langmuir–Blodgett technique show the higher photoluminescence intensity and the shift to the shorter wavelengths compared to the infrared photoluminescence spectra of the PbS nanoparticles prepared by the laser ablation from PbS target. We aslo proved the high stability of PbS nanoparticles prepared in the form of thin layers.

  14. Temperature dependences of the photoluminescence intensities of centers in silicon implanted with erbium and oxygen ions

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Shtel’makh, K. F.; Kalyadin, A. E.; Shek, E. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2015-12-15

    Low-temperature photoluminescence in n-Cz-Si after the implantation of erbium ions at an elevated temperature and subsequent implantation of oxygen ions at room temperature is studied. So-called X and W centers formed from self-interstitial silicon atoms, H and P centers containing oxygen atoms, and Er centers containing Er{sup 3+} ions are observed in the photoluminescence spectra. The energies of enhancing and quenching of photoluminescence for these centers are determined. These energies are determined for the first time for X and H centers. In the case of P and Er centers, the values of the energies practically coincide with previously published data. For W centers, the energies of the enhancing and quenching of photoluminescence depend on the conditions of the formation of these centers.

  15. Mid-Infrared Photoluminescence of CdS and CdSe Colloidal Quantum Dots.

    Science.gov (United States)

    Jeong, Kwang Seob; Guyot-Sionnest, Philippe

    2016-02-23

    Mid-infrared intraband photoluminescence is observed from CdSe and CdS colloidal quantum dots (CQDs) and core/shell systems when excited by a visible laser. The CQDs show more intraband photoluminescence with dodecanethiol than with other ligands. Core/shells show an increase of the intraband photoluminescence with increasing shell thickness. The detected emission is restricted to below 2900 cm(-1), bounded by the C-H vibrational modes of the organic ligands. Upon photoexcitation in air for all dodecanethiol ligands capped CQD systems studied, the intraband photoluminescence is quenched over time, and emission at lower frequency is observed, which is assigned to laser heating and thermal emission from oxides.

  16. Photoluminescence response of colloidal quantum dots on VO2 film across metal to insulator transition.

    Science.gov (United States)

    Kuznetsov, Sergey N; Cheremisin, Alexander B; Stefanovich, Genrikh B

    2014-01-01

    We have proposed a method to probe metal to insulator transition in VO2 measuring photoluminescence response of colloidal quantum dots deposited on the VO2 film. In addition to linear luminescence intensity decrease with temperature that is well known for quantum dots, temperature ranges with enhanced photoluminescence changes have been found during phase transition in the oxide. Corresponding temperature derived from luminescence dependence on temperature closely correlates with that from resistance measurement during heating. The supporting reflectance data point out that photoluminescence response mimics a reflectance change in VO2 across metal to insulator transition. Time-resolved photoluminescence study did not reveal any significant change of luminescence lifetime of deposited quantum dots under metal to insulator transition. It is a strong argument in favor of the proposed explanation based on the reflectance data. 71.30. + h; 73.21.La; 78.47.jd.

  17. Brightening of carbon nanotube photoluminescence through the incorporation of sp3 defects.

    Science.gov (United States)

    Piao, Yanmei; Meany, Brendan; Powell, Lyndsey R; Valley, Nicholas; Kwon, Hyejin; Schatz, George C; Wang, YuHuang

    2013-10-01

    Semiconducting carbon nanotubes promise a broad range of potential applications in optoelectronics and imaging, but their photon-conversion efficiency is relatively low. Quantum theory suggests that nanotube photoluminescence is intrinsically inefficient because of low-lying 'dark' exciton states. Here we demonstrate the significant brightening of nanotube photoluminescence (up to 28-fold) through the creation of an optically allowed defect state that resides below the predicted energy level of the dark excitons. Emission from this new state generates a photoluminescence peak that is red-shifted by as much as 254 meV from the nanotube's original excitonic transition. We also found that the attachment of electron-withdrawing substituents to carbon nanotubes systematically drives this defect state further down the energy ladder. Our experiments show that the material's photoluminescence quantum yield increases exponentially as a function of the shifted emission energy. This work lays the foundation for chemical control of defect quantum states in low-dimensional carbon materials.

  18. One-Step Synthesis and Photoluminescence Eva-luation of Cadmium-containing Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    Nisha Shukla; Michael M Nigra; Abigail D Ondeck

    2012-01-01

    We have developed a simple one-step process for synthesis of ternary quantum dots (ZnCdSe, MgCdSe) with photoluminescence wavelengths ranging from the red to the blue region of the visible spectrum. The primary aim of this work was to develop a synthesis for the preparation of Cd-containing quantum dots using a Cd precursor with lower toxicity than those used in common syntheses. This synthesis makes use of Cd(acac)2 which is significantly less toxic than precursors such as CdO and CdCl2 . We have studied the effect of solvent boiling point, precursors and reaction time on the photoluminescence properties of the ternary quantum dots. Ternary quantum dots synthesized from Cd(acac)2 in low boiling point solvents have photoluminescence wavelengths in the blue region, while those synthesized in high boiling point solvents have photoluminescence wavelengths in the red region.

  19. Enhancement of QDs photoluminescence by localized surface plasmon effect of Au-NPs

    Science.gov (United States)

    Heydari, Esmaeil; Greco, Tonino; Stumpe, Joachim

    2012-04-01

    Photoluminescence enhancement of CdSe/CdS/ZnS QDs by localized surface plasmon resonance of large Au-NPs has been investigated. The photoluminescence of the QDs with an emission wavelength at 620 nm in a PMMA matrix is enhanced by immobilized Au-NPs. By considering the lifetime and excitation dependent photoluminescence we realized that the emission and excitation rate enhancements both contributed to the total photoluminescence enhancement. PL measurements were carried out for different sizes of Au-NPs to find out their influences on the emission of QDs. The largest enhancement is achieved by applying 80 nm Au-NPs. Silanization method gives us the opportunity easily to prepare samples with different concentrations of Au-NPs. It is revealed that increasing the concentration of the Au-NPs layer provides higher scattering cross section which contributes in PL enhancement.

  20. Synthesis and photoluminescence behavior of difluoroboron complexes with β-diketone ligands

    Science.gov (United States)

    Wang, Dun-Jia; Kang, Yan-Fang; Fan, Ling; Hu, Yan-Jun; Zheng, Jing

    2013-12-01

    Five new difluoroboron complexes with 4-pyridyl-β-diketones were synthesized and their structures were confirmed by elemental analysis, IR, 1H NMR, ESI-MS and UV-vis spectroscopy. Their photoluminescence behavior was studied in DMF solution and solid state. The quantum yields (Φu) of complexes 2a-2e in DMF solution were measured relative to quinine sulfate and their lifetime values (τ) were calculated according to the luminescence decay curves in the solid state. From these data, the difluoroboron complexes exhibited the excellent photoluminescence properties. Especially, the complexes 2d and 2e displayed the stronger photoluminescence intensity, much higher quantum yield and longer lifetime value as compared to complexes 2a, 2b and 2c. The results indicate that the substituents at the 4-position on benzene ring have a significant impacts on the photoluminescence properties of the difluoroboron complexes.

  1. Crystal Crosslinked Gels with Aggregation-Induced Emissive Crosslinker Exhibiting Swelling Degree-Dependent Photoluminescence

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Oura

    2017-01-01

    Full Text Available The synthesis and photoluminescence properties of crystal crosslinked gels (CCGs with an aggregation-induced emission (AIE active crosslinker derived from tetraphenylethene (TPE is discussed in this article. The CCG was prepared from a metal organic framework (MOF with large pore aperture to allow the penetration of TPE crosslinker. The obtained CCG possessed a rectangular shape originated from the parent MOF, KUMOF. The CCG showed stimuli-responsive photoluminescence behavior depending on the swelling degree, thus the photoluminescence intensity was higher at higher swelling degree. By changing the solvent, water content, or ionic strength, the photoluminescence intensity was controllable, accompanying the change of swelling degree. Moreover, emission color tuning was also achieved by the introduction of luminescent rare earth ions to form a coordination bonding with residual carboxylate inside the CCG.

  2. Electrospun nanofibers of poly(vinyl pyrrolidone)/Eu3+ and its photoluminescence properties

    Institute of Scientific and Technical Information of China (English)

    Shan Shan Tang; Chang Lu Shao; Shou Zhu Li

    2007-01-01

    Nanofibers of poly(vinyl pyrrolidone) (PVP)/Eu3+ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL). The results indicated that, Eu3+ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu3+ hybrid nanofibers had favorable photoluminescence properties.

  3. Temperature dependence of the photoluminescence from ensembles of amorphous silicon nanoparticles with various average sizes.

    Science.gov (United States)

    Brüggemann, R; Nesheva, D; Meier, S; Bineva, I

    2011-02-01

    Amorphous SiO(x) thin films with three different oxygen contents (x = 1.3, 1.5, and 1.7) have been deposited by thermal evaporation of SiO in vacuum. Partial phase separation in the films has been induced by annealing at 773 or 973 K in argon for 60 and 120 min and thus Si-SiO(x) composite films have been prepared containing amorphous Si nanoparticles of various sizes (Photoluminescence from the films has been measured in the temperature range 20-296 K. The single Gauss band observed in the photoluminescence spectra of the samples with x = 1.3 and centered in the range 1.55-1.75 eV has been related to radiative recombination in Si nanoparticles. Two bands, a red-orange one (related to radiative recombination in Si nanoparticles) and a green band peaked at approximately 2.3 eV (related to radiative recombination via defects) have been resolved in the photoluminescence spectra of the films with x = 1.5 and 1.7. The band in the spectra of the x = 1.3 samples has shown a relative strong thermal quenching but it is significantly weaker than the photoluminescence quenching in bulk a-Si. Besides, the higher the initial oxygen content, the weaker is the photoluminescence thermal quenching. These observations have been related to carrier confinement which is stronger in smaller nanoparticles. The thermally induced photoluminescence decrease with increasing temperature in the samples with x = 1.3 obeys the relation that is characteristic for bulk a-Si:H while the photoluminescence decrease in x = 1.5 and 1.7 samples is of Arrhenius type. We suggest that in nanoparticles larger than 2 nm recombination via band tail states is the dominating photoluminescence mechanism while in smaller nanoparticles exciton-like recombination dominates.

  4. Optically Monitoring Mineralization and Demineralization on Photoluminescent Bioactive Nanofibers.

    Science.gov (United States)

    Li, Xiang; Li, Yangyang; Chen, Xiaoyi; Li, Binbin; Gao, Bo; Ren, Zhaohui; Han, Gaorong; Mao, Chuanbin

    2016-04-05

    Bone regeneration and scaffold degradation do not usually follow the same rate, representing a daunting challenge in bone repair. Toward this end, we propose to use an external field such as light (in particular, a tissue-penetrating near-infrared light) to precisely monitor the degradation of the mineralized scaffold (demineralization) and the formation of apatite mineral (mineralization). Herein, CaTiO3:Yb(3+),Er(3+)@bioactive glass (CaTiO3:Yb(3+),Er(3+)@BG) nanofibers with upconversion (UC) photoluminescence (PL) were synthesized. Such nanofibers are biocompatible and can emit green and red light under 980 nm excitation. The UC PL intensity is quenched during the bone-like apatite formation on the surface of the nanofibers in simulated body fluid; more mineral formation on the nanofibers induces more rapid optical quenching of the UC PL. Furthermore, the quenched UC PL can recover back to its original magnitude when the apatite on the nanofibers is degraded. Our work suggests that it is possible to optically monitor the apatite mineralization and demineralization on the surface of nanofibers used in bone repair.

  5. Photoluminescence Characterization of Nanocrystalline ZnO Array

    Institute of Scientific and Technical Information of China (English)

    CHANG Yong-Qin; YU Da-Peng; LI Guo-Hua; FANG Zai-Li; ZHANG Ye; CHEN Yao-Feng; YANG FU-Hua

    2004-01-01

    @@ High-density and uniform well-aligned ZnO sub-micron rods are synthesized on the silicon substrate over a large area. The morphology and structure of the ZnO sub-micron rods are investigated by x-ray diffraction, transmission electron microscopy and Raman spectra. It is found that the ZnO sub-micron rods are of high crystal quality with the diameter in the range of 400-600 nm and the length of several micrometres long. The optical properties were studied by photoluminescence spectra. The results show that the intensity of the ultraviolet emission at 3.3 eV is rather high, meanwhile the deep level transition centred at about 2.38eV is weak. The free exciton emission could also be observed at low temperature, which implies the high optical quality of the ZnO sub-micron rods.This growth technique provides one effective way to fabricate the high crystal quality ZnO nanowires array, which is very important for potential applications in the new-type optoelectronic nanodevices.

  6. Enhanced photoluminescence of porous silicon nanoparticles coated by bioresorbable polymers

    Science.gov (United States)

    Gongalsky, Maxim B.; Kharin, Alexander Yu; Osminkina, Liubov A.; Timoshenko, Victor Yu; Jeong, Jinyoung; Lee, Han; Chung, Bong Hyun

    2012-08-01

    A significant enhancement of the photoluminescence (PL) efficiency is observed for aqueous suspensions of porous silicon nanoparticles (PSiNPs) coated by bioresorbable polymers, i.e., polylactic-co-glycolic acid (PLGA) and polyvinyl alcohol (PVA). PSiNPs with average size about 100 nm prepared by mechanical grinding of electrochemically etched porous silicon were dispersed in water to prepare the stable suspension. The inner hydrophobic PLGA layer prevents the PSiNPs from the dissolution in water, while the outer PVA layer makes the PSiNPs hydrophilic. The PL quantum yield of PLGA/PVA-coated PSiNPs was found to increase by three times for 2 weeks of the storage in water. The observed effect is explained by taking into account both suppression of the dissolution of PSiNPs in water and a process of the passivation of nonradiative defects in PSiNPs. The obtained results are interesting in view of the potential applications of PSiNPs in bioimaging.

  7. Photoluminescence Properties of Nanocrystalline 3C-SiC Films

    Institute of Scientific and Technical Information of China (English)

    YU Wei; LU Xue-qin; LU Wan-bing; HAN Li; FU Guang-sheng

    2006-01-01

    Nanocrystalline (nc) 3C-SiC films on the Si substrate were prepared by the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. With the SiH4-CH4 gas flow ratio changing, the films exhibit different photoluminescence (PL) characteristics. Under the stoichiometric condition, the PL peak redshift from 470 nm to 515 nm is detected with the increase of excitation wavelength, which can be attributed to the quantum confinement effect radiation of 3C-SiC nanocrystals of different sizes. However, the appearance of an additional PL band at 436 nm in Si-rich film might be sourced back to the excess of Si defect centers in it. This is also the case for C-rich film for its PL band lying at 570 nm. The results above quoted indicate an important influence of gas flow ratio on the PL properties of the SiC films providing an effective guidance for analyzing the luminescence mechanism and exploring the high-efficiency light emission of the SiC films.

  8. Tuning photoluminescence of organic rubrene nanoparticles through a hydrothermal process

    Directory of Open Access Journals (Sweden)

    Jung Hyunjung

    2011-01-01

    Full Text Available Abstract Light-emitting 5,6,11,12-tetraphenylnaphthacene (rubrene nanoparticles (NPs prepared by a reprecipitation method were treated hydrothermally. The diameters of hydrothermally treated rubrene NPs were changed from 100 nm to 2 μm, depending on hydrothermal temperature. Photoluminescence (PL characteristics of rubrene NPs varied with hydrothermal temperatures. Luminescence of pristine rubrene NPs was yellow-orange, and it changed to blue as the hydrothermal temperature increased to 180°C. The light-emitting color distribution of the NPs was confirmed using confocal laser spectrum microscope. As the hydrothermal temperature increased from 110°C to 160°C, the blue light emission at 464 to approximately 516 nm from filtered-down NPs was enhanced by H-type aggregation. Filtered-up rubrene NPs treated at 170°C and 180°C exhibited blue luminescence due to the decrease of intermolecular excimer densities with the rapid increase in size. Variations in PL of hydrothermally treated rubrene NPs resulted from different size distributions of the NPs.

  9. Combustion synthesis and photoluminescence study of silicate biomaterials

    Indian Academy of Sciences (India)

    V B Bhatkar; N V Bhatkar

    2011-10-01

    Silicate based bioceramics are promising candidates as biomaterials for tissue engineering. The combustion synthesis method provides control on the morphology and particle size of the synthesized material. This paper discusses the combustion synthesis of akermanite (Ca2MgSi2O7 and Sr2MgSi2O7), which has been shown to have good in vitro and in vivo bioactivities by earlier studies. Both Ca2MgSi2O7 and Sr2MgSi2O7 have akermanite structure. Ca2MgSi2O7 and Sr2MgSi2O7 were prepared using urea and ammonium nitrate. The combustion synthesis using urea and ammonium nitrate was found to be cost effective and efficient method of synthesis. The photoluminescence study of Ca2MgSi2O7 : Eu2+ and Sr2MgSi2O7 :Eu2+ shows host specific intense emission of Eu2+.

  10. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Po-Han Chan

    Full Text Available Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs. The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm. The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6 cells/mL.

  11. Photoluminescence decay rate of silicon nanoparticles modified with gold nanoislands

    Science.gov (United States)

    Dan'ko, Viktor; Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro

    2014-04-01

    We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO x matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si . It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO x sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate .

  12. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Science.gov (United States)

    Chan, Po-Han; Ghosh, Bhaswati; Lai, Hong-Zheng; Peng, Hwei-Ling; Mong, Kwok Kong Tony; Chen, Yu-Chie

    2013-01-01

    Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6) cells/mL.

  13. Photoluminescence spectra of some ternary and quaternary chalcopyrite semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Elfotouh, F.; Dunlavy, D.J.; Kazmerski, L.L.; Albin, D.; Bachman, K.J.; Menner, R.

    1988-05-01

    Photoluminescence (PL) emission spectra of single crystals and thin films of CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ compounds have been investigated at various measuring temperatures, and compared with the emission from CuGaSe/sub 2/ and CuInSe/sub 2/. The observed PL spectra consisted of two groups of emission lines: the near-band-gap group (A) and the lower energy group (B). It was found that the type of emission obtained is determined by the amount of stoichiometry and molecularity deviations. The PL data also showed a correspondence between the defect related transitions from the CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ solid solution and CuGaSe/sub 2/ for x<0.5. Based on the intrinsic defect states in the two components CuInSe/sub 2/ and CuGaSe/sub 2/, the predominant defect states transitions in the solid solution are defined for the m<1 and ..delta..S>0. Interpretation of the PL spectra of Se-deficient compounds with m>1 are rather complicated, and much work remains to be done before the defect chemistry of CuGa/sub x/In/sub 1/..sqrt../sub x/Se/sub 2/ could be fully understood.

  14. Modulation of porphyrin photoluminescence by nanoscale spacers on silicon substrates

    Science.gov (United States)

    Fang, Y. C.; Zhang, Y.; Gao, H. Y.; Chen, L. G.; Gao, B.; He, W. Z.; Meng, Q. S.; Zhang, C.; Dong, Z. C.

    2013-11-01

    We investigate photoluminescence (PL) properties of quasi-monolayered tetraphenyl porphyrin (TPP) molecules on silicon substrates modulated by three different nanoscale spacers: native oxide layer (NOL), hydrogen (H)-passivated layer, and Ag nanoparticle (AgNP) thin film, respectively. In comparison with the PL intensity from the TPP molecules on the NOL-covered silicon, the fluorescence intensity from the molecules on the AgNP-covered surface was greatly enhanced while that for the H-passivated surface was found dramatically suppressed. Time-resolved fluorescence spectra indicated shortened lifetimes for TPP molecules in both cases, but the decay kinetics is believed to be different. The suppressed emission for the H-passivated sample was attributed to the weaker decoupling effect of the monolayer of hydrogen atoms as compared to the NOL, leading to increased nonradiative decay rate; whereas the enhanced fluorescence with shortened lifetime for the AgNP-covered sample is attributed not only to the resonant excitation by local surface plasmons, but also to the increased radiative decay rate originating from the emission enhancement in plasmonic "hot-spots".

  15. 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.

  16. Photoluminescence properties of TiO2 nanofibers

    Science.gov (United States)

    Chetibi, Loubna; Busko, Tetiana; Kulish, Nikolay Polikarpovich; Hamana, Djamel; Chaieb, Sahraoui; Achour, Slimane

    2017-04-01

    Multi-walled carbon nanotube (MWCNT)-TiO2 nanofiber (NF) composites forming a layered nanostructure (MWCNTs/TiO2 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 TiO2 NFs where the MWCNTs can act as an electron reservoir of electrons emitted from TiO2 nanofibers when irradiated with UV light. The combination of MWCNTs and TiO2 results in quenching of TiO2 luminescence in the visible range. In addition, the prepared surface of MWCNTs-TiO2 was irradiated with Ti+ ions using irradiation energy of 140 keV and doses of 1013 ions/cm2. Also, this treatment induced the PL intensity quenching due to the generation of non-radiative additional levels inside the band gap.

  17. Photoluminescent carbon nanotubes interrogate the permeability of multicellular tumor spheroids

    Science.gov (United States)

    Shah, Janki; Roxbury, Daniel; Paknejad, Navid; Heller, Daniel A.

    2015-01-01

    Nanomaterials have been extensively investigated for cancer drug delivery and imaging applications. Nanoparticles that show promise in two-dimensional cell culture systems often fail in more complex environments, possibly due to the lack of penetration in dense, three-dimensional structures. Multicellular tumor spheroids are an emerging model system to investigate interactions of nanoparticles with 3D in vitro cell culture environments. Using the intrinsic near-infrared emission of semiconducting carbon nanotubes to optically reconstruct their localization within a three-dimensional volume, we resolved the relative permeability of two different multicellular tumor spheroids. Nanotube photoluminescence revealed that nanotubes rapidly internalized into MCF-7 breast cancer cell-derived spheroids, whereas they exhibited little penetration into spheroids derived from SK-136, a cell line that we developed from murine liver cancer. Characterization of the spheroids by electron microscopy and immunohistochemistry revealed large differences in the extracellular matrix and interstitial spacing, which correlated directly with nanotube penetration. This platform portends a new approach to characterize the permeability of living multicellular environments. PMID:26456974

  18. Synthesis and Photoluminescence Properties of Porous Silicon Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Wang Yan

    2010-01-01

    Full Text Available Abstract Herein, we prepare vertical and single crystalline porous silicon nanowires (SiNWs via a two-step metal-assisted electroless etching method. The porosity of the nanowires is restricted by etchant concentration, etching time and doping lever of the silicon wafer. The diffusion of silver ions could lead to the nucleation of silver nanoparticles on the nanowires and open new etching ways. Like porous silicon (PS, these porous nanowires also show excellent photoluminescence (PL properties. The PL intensity increases with porosity, with an enhancement of about 100 times observed in our condition experiments. A “red-shift” of the PL peak is also found. Further studies prove that the PL spectrum should be decomposed into two elementary PL bands. The peak at 850 nm is the emission of the localized excitation in the nanoporous structure, while the 750-nm peak should be attributed to the surface-oxidized nanostructure. It could be confirmed from the Fourier transform infrared spectroscopy analyses. These porous SiNW arrays may be useful as the nanoscale optoelectronic devices.

  19. Photoluminescence origin of nanocrystalline SiC films

    Institute of Scientific and Technical Information of China (English)

    LIU Ji-wen; LI Juan; LI Yan-hui; LI Chang-ling; ZHAO Yan-ping; ZHAO Jie; XU Jing-jun

    2005-01-01

    The nanocrystalline SiC films were prepared on Si (111) substrates by rf magnetron sputtering and then annealed at 800℃ and 1 000℃ for 30 minutes in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared (FTIR) absorption spectra and the X-ray diffraction (XRD) analysis. Measurement of photoluminescence (PL) of the nanocrystalline SiC (nc-SiC) films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap.The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.

  20. Photoluminescence evolution in self-ion-implanted and annealed silicon

    Institute of Scientific and Technical Information of China (English)

    Yang Yu; Wang Chong; Yang Rui-Dong; Li Liang; Xiong Fei; Bao Ji-Ming

    2009-01-01

    Si+ ion-implanted silicon wafers are annealed at different temperatures from room temperature to 950℃ and then characterized by using the photoluminescence (PL) technique at different recorded temperatures (RETs). Plentiful optical features are observed and identified clearly in these PL curves. The PL spectra of these samples annealed in different temperature ranges are correspondingly dominated by different emission peaks. Several characteristic features, such as an R line, S bands, a W line, the phonon-assistant W~(TA) and Si~(TO) peaks, can be detected in the PL spectra of samples annealed at different temperatures. For the samples annealed at 800 ℃, emission peaks from the dislocations bounded at the deep energy levels of the forbidden band, such as D_1 and D_2 bands, can be observed at a temperature as high as 280 K. These data strongly indicate that a severe transformation of defect structures could be manipulated by the annealing and recorded temperatures. The deactivation energies of the main optical features are extracted from the PL data at different temperatures.

  1. 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.)

  2. Low-temperature photoluminescence in self-assembled diphenylalanine microtubes

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, T. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopyl, S. [Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal); Shur, V.Ya. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopelevich, Y.V., E-mail: kopel@ifi.unicamp.br [Instituto de Fisica, UNICAMP, Campinas, São Paulo 13083-859 (Brazil); Kholkin, A.L., E-mail: kholkin@gmail.com [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal)

    2016-04-22

    Bioinspired self-assembled structures are increasingly important for a variety of applications ranging from drug delivery to electronic and energy harvesting devices. An important class of these structures is diphenylalanine microtubes which are potentially important for optical applications including light emitting diodes and optical biomarkers. In this work we present the data on their photoluminescent properties at low temperatures (down to 12 K) and discuss the origin of the emission in the near ultraviolet (UV) range seen earlier in a number of reports. UV luminescence increases with decreasing temperature and exhibits several equidistant lines that are assigned to zero-phonon exciton emission line and its phonon replicas. We infer that the exciton is localized on the defect sites and significant luminescence decay is due to thermal quenching arising from the carrier excitation from these defects and non-radiative recombination. - Highlights: • Low-temperature luminescence is studied in bioinspired self-assembled FF peptide microtubes. • The mechanism of the optical emission is assigned to the luminescence of excitonic states localized at defects. • Luminescence in FF microtubes can be used as an absolute temperature probe at low temperature.

  3. Photoluminescence quenching in gold - MoS2 hybrid nanoflakes

    Science.gov (United States)

    Bhanu, Udai; Islam, Muhammad R.; Tetard, Laurene; Khondaker, Saiful I.

    2014-01-01

    Achieving tunability of two dimensional (2D) transition metal dichalcogenides (TMDs) functions calls for the introduction of hybrid 2D materials by means of localized interactions with zero dimensional (0D) materials. A metal-semiconductor interface, as in gold (Au) - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science as it constitutes an outstanding platform to investigate plasmonic-exciton interactions and charge transfer. The applied aspects of such systems introduce new options for electronics, photovoltaics, detectors, gas sensing, catalysis, and biosensing. Here we consider pristine MoS2 and study its interaction with Au nanoislands, resulting in local variations of photoluminescence (PL) in Au-MoS2 hybrid structures. By depositing monolayers of Au on MoS2, we investigate the electronic structure of the resulting hybrid systems. We present strong evidence of PL quenching of MoS2 as a result of charge transfer from MoS2 to Au: p-doping of MoS2. The results suggest new avenues for 2D nanoelectronics, active control of transport or catalytic properties. PMID:24992896

  4. Structure and Photoluminescence of Mullite.Ge Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    GAO Le; WANG Hao; WANG Weimin; FU Zhengyi

    2008-01-01

    Al12Si3.75Ge0.25O26 ceramic powder was prepared by sol-gel method using Al(NO3)3,Si(OC2H5)4 and Cl3GeCH2-CH2COOH as precursors.The structural formation of Al12Si3.75Ge0.25O26 ceramic powder was analyzed by XRD.After reduction by flowing H2/Ar mixture gas,strong room temperature photoluminescence (PL) can be observed at 565 nm,613 nm,682 nm,731 nm and 777 nm,respectively.The PL intensity scarcely depends on the reduction temperature and duration,while the sample reduced at 500 ℃ for 3 hours has the highest PL intensity.Before and after reduction at 500 ℃,the volume of unit cell of mullite solid solution decreases to 0.4699 (A)3.Based on the analysis of XPS and Raman spectra,it can be approved that the PL phenomenon at room temperature is caused by the embedded Ge nanoparticles with the average size of about 1.95 nm.

  5. Photoluminescence enhancement in double Ge/Si quantum dot structures

    Science.gov (United States)

    Zinovieva, A. F.; Zinovyev, V. A.; Nikiforov, A. I.; Timofeev, V. A.; Mudryi, A. V.; Nenashev, A. V.; Dvurechenskii, A. V.

    2016-12-01

    Luminescence properties of double Ge/Si quantum dot structures were studied at liquid helium temperature depending on the Si spacer thickness d in QD molecules. A seven-fold increase of the integrated photoluminescence intensity was obtained for the structures with optimal thickness d = 2 nm. This enhancement is explained by increasing the overlap integral of electron and hole wave functions. Two main factors promote this increasing. The first one is that the electrons are localized at the QD base edges and their wave functions are the linear combinations of the states of in-plane Δ valleys, which are perpendicular in k-space to the growth direction [001]. This results in the increasing probability of electron penetration into Ge barriers. The second factor is the arrangement of Ge nanoclusters in closely spaced QD groups. The strong tunnel coupling of QDs within these groups increases the probability of hole finding at the QD base edge, that also promotes the increase of the radiative recombination probability.

  6. Europium polyoxometalates encapsulated in silica nanoparticles - characterization and photoluminescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Cristina S.; Granadeiro, Carlos M.; Cunha-Silva, Luis; Eaton, Peter; Balula, Salete S.; Pereira, Eulalia [REQUIMTE/Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto (Portugal); Ananias, Duarte [CICECO, Departamento de Quimica, Universidade de Aveiro (Portugal); Gago, Sandra [REQUIMTE, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica (Portugal); Feio, Gabriel [CENIMAT/I3N, Departamento de Ciencia dos Materiais, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Monte de Caparica (Portugal); Carvalho, Patricia A. [ICEMS/Departamento de Bioengenharia, Instituto Superior Tecnico, Lisboa (Portugal)

    2013-06-15

    The incorporation of europium polyoxometalates into silica nanoparticles can lead to a biocompatible nanomaterial with luminescent properties suitable for applications in biosensors, biological probes, and imaging. Keggin-type europium polyoxometalates Eu(PW{sub 11}){sub x} (x = 1 and 2) with different europium coordination environments were prepared by using simple methodologies and no expensive reactants. These luminescent compounds were then encapsulated into silica nanoparticles for the first time through the water-in-oil microemulsion methodology with a nonionic surfactant. The europium polyoxometalates and the nanoparticles were characterized by using several techniques [FTIR, FT-Raman, {sup 31}P magic angle spinning (MAS) NMR, and TEM/energy-dispersive X-ray spectroscopy (TEM-EDS), AFM, dynamic light scattering (DLS), and inductively coupled plasma MS (ICP-MS) analysis]. The stability of the material and the integrity of the europium compounds incorporated were also examined. Furthermore, the photoluminescence properties of the Eu(PW{sub 11}){sub x} rate at SiO{sub 2} nanomaterials were evaluated and compared with those of the free europium polyoxometalates. The silica surface of the most stable nanoparticles was successfully functionalized with appropriate organosilanes to enable the covalent binding of oligonucleotides. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Thermodynamic of photoluminescence far from the radiative limit

    CERN Document Server

    Manor, Assaf; Rotschild, Carmel

    2016-01-01

    The radiance of thermal emission, as described by Plancks law, depends only on the emissivity and temperature of a body, and increases monotonically with temperature rise at any emitted wavelength. Nonthermal 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. Until recently, the role of rate conservation when thermal excitation is significant, has not been studied in any nonthermal radiation. A question: What is the overall emission rate if a high quantum efficiency (QE), PL material, is heated to a temperature where it thermally emits a rate of 50 photons/sec at its bend edge, while in parallel is PL excited at a rate of 100 photons/sec. Recently, we discovered that the answer is an overall rate of 100 blueshifted photons/sec. In contrast to thermal emission, the PL rate is conserved with temperature increase, while each photon is blueshifted. Further ...

  8. 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.

  9. Photoluminescence of phosphorus atomic layer doped Ge grown on Si

    Science.gov (United States)

    Yamamoto, Yuji; Nien, Li-Wei; Capellini, Giovanni; Virgilio, Michele; Costina, Ioan; Schubert, Markus Andreas; Seifert, Winfried; Srinivasan, Ashwyn; Loo, Roger; Scappucci, Giordano; Sabbagh, Diego; Hesse, Anne; Murota, Junichi; Schroeder, Thomas; Tillack, Bernd

    2017-10-01

    Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 × 1013 cm‑2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm‑3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm‑3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ∼0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ∼2 × 1019 cm‑3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.

  10. 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.

  11. Maximizing Photoluminescence Extraction in Silicon Photonic Crystal Slabs.

    Science.gov (United States)

    Mahdavi, Ali; Sarau, George; Xavier, Jolly; Paraïso, Taofiq K; Christiansen, Silke; Vollmer, Frank

    2016-04-26

    Photonic crystal modes can be tailored for increasing light matter interactions and light extraction efficiencies. These PhC properties have been explored for improving the device performance of LEDs, solar cells and precision biosensors. Tuning the extended band structure of 2D PhC provides a means for increasing light extraction throughout a planar device. This requires careful design and fabrication of PhC with a desirable mode structure overlapping with the spectral region of emission. We show a method for predicting and maximizing light extraction from 2D photonic crystal slabs, exemplified by maximizing silicon photoluminescence (PL). Systematically varying the lattice constant and filling factor, we predict the increases in PL intensity from band structure calculations and confirm predictions in micro-PL experiments. With the near optimal design parameters of PhC, we demonstrate more than 500-fold increase in PL intensity, measured near band edge of silicon at room temperature, an enhancement by an order of magnitude more than what has been reported.

  12. Three-Photon Absorption Induced Photoluminescence in Organo-Lead Mixed Halide Perovskites

    Science.gov (United States)

    Phan Vu, Thi Van; Nguyen, Minh Tu; Nguyen, Dam Thuy Trang; Vu, Tien Dung; Nguyen, Duc Long; An, Ngoc Mai; Nguyen, Minh Hieu; Sai, Cong Doanh; Bui, Van Diep; Hoang, Chi Hieu; Truong, Thanh Tu; Lai, Ngoc Diep; Nguyen-Tran, Thuat

    2017-06-01

    Organo-lead mixed halide perovskites have been showing remarkable performance for applications in solar cells and are very promising for numerous applications in optoelectronics and nonlinear optics. In this study, we report a room-temperature photoluminescence study of this material by using pulsed excitation laser sources at 1064 nm wavelength. Under our experimental conditions, strong photoluminescence was observed only for bromine-containing perovskites, CH3NH3Pb(I1-xBrx)3, thus suggesting an important role of bromine for photoluminescence of halide perovskites. The experimental results also showed that the photoluminescence peak was blue-shifted from 727 nm to 574 nm when x increased from 1/3 to 1. In particular, the photoluminescence peak featured a third-order dependence on the laser intensity. This direct observation of three-photon absorption-induced photoluminescence of organo-lead mixed halide perovskite materials thus opens up interesting applications in the field of optoelectronics and nonlinear optics.

  13. 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.

  14. Fourier transform infrared spectroscopy approach for measurements of photoluminescence and electroluminescence in mid-infrared

    Science.gov (United States)

    Zhang, Y. G.; Gu, Y.; Wang, K.; Fang, X.; Li, A. Z.; Liu, K. H.

    2012-05-01

    An improved Fourier transform infrared spectroscopy approach adapting to photoluminescence and electroluminescence measurements in mid-infrared has been developed, in which diode-pumped solid-state excitation lasers were adopted for photoluminescence excitation. In this approach, three different Fourier transform infrared modes of rapid scan, double modulation, and step scan were software switchable without changing the hardware or connections. The advantages and limitations of each mode were analyzed in detail. Using this approach a group of III-V and II-VI samples from near-infrared extending to mid-infrared with photoluminescence intensities in a wider range have been characterized at room temperature to demonstrate the validity and overall performances of the system. The weaker electroluminescence of quantum cascade lasers in mid-infrared band was also surveyed at different resolutions. Results show that for samples with relatively strong photoluminescence or electroluminescence out off the background, rapid scan mode is the most preferable. For weaker photoluminescence or electroluminescence overlapped with background, double modulation is the most effective mode. To get a better signal noise ratio when weaker photoluminescence or electroluminescence signal has been observed in double modulation mode, switching to step scan mode should be an advisable option despite the long data acquiring time and limited resolution.

  15. Fourier transform infrared spectroscopy approach for measurements of photoluminescence and electroluminescence in mid-infrared.

    Science.gov (United States)

    Zhang, Y G; Gu, Y; Wang, K; Fang, X; Li, A Z; Liu, K H

    2012-05-01

    An improved Fourier transform infrared spectroscopy approach adapting to photoluminescence and electroluminescence measurements in mid-infrared has been developed, in which diode-pumped solid-state excitation lasers were adopted for photoluminescence excitation. In this approach, three different Fourier transform infrared modes of rapid scan, double modulation, and step scan were software switchable without changing the hardware or connections. The advantages and limitations of each mode were analyzed in detail. Using this approach a group of III-V and II-VI samples from near-infrared extending to mid-infrared with photoluminescence intensities in a wider range have been characterized at room temperature to demonstrate the validity and overall performances of the system. The weaker electroluminescence of quantum cascade lasers in mid-infrared band was also surveyed at different resolutions. Results show that for samples with relatively strong photoluminescence or electroluminescence out off the background, rapid scan mode is the most preferable. For weaker photoluminescence or electroluminescence overlapped with background, double modulation is the most effective mode. To get a better signal noise ratio when weaker photoluminescence or electroluminescence signal has been observed in double modulation mode, switching to step scan mode should be an advisable option despite the long data acquiring time and limited resolution.

  16. Tuning photoluminescence of ZnS nanoparticles by silver

    Indian Academy of Sciences (India)

    A Murugadoss; Arun Chattopadhyay

    2008-06-01

    We report the results of investigation of the interaction of silver with presynthesized ZnS nanoparticles (NPs) that was stabilized by cetyl trimethyl ammonium bromide (CTAB). The photoluminescence properties of ZnS NPs were followed in the presence of Ag+ ions, Ag NPs and by the synthesis of Ag@ZnS core-shell nanoparticles. We observed that CTAB stabilized ZnS NPs emitted broadly in the region from 350–450 nm, when excited by 309 nm light. In the presence of Ag+ ions the emission peak intensity up to 400 nm was reduced, while two new and stronger peaks at 430 nm and 550 nm appeared. Similar results were obtained when Ag NPs solution was added to ZnS solution. However, when Ag@ZnS NPs were synthesized, the emission in the 350–450 nm region was much weaker in comparison to that at 540 nm, which itself appeared at a wavelength shorter than that of Ag+ ion added ZnS NPs. The observations have been explained by the presence of interstitial sulfur and Zn2+, especially near the surface of the nanocrystals and their interaction with various forms of silver. In addition, our observations suggest that Ag+ ions diffuse into the lattice of the preformed ZnS NPs just like the formation of Ag+ doped ZnS NPs and thus changes the emission characteristics. We also have pursued similar experiments with addition of Mn2+ ions to ZnS and observed similar results of emission characteristics of Mn2+ doped ZnS NPs. We expect that results would stimulate further research interests in the development of fluoremetric metal ion sensors based on interaction with quantum dots.

  17. Polarized photoluminescence from nematic and chiral- nematic liquid crystalline films

    Science.gov (United States)

    Conger, Brooke Morgan

    Polarization control is key to optoelectronics in terms of the processing and display of optical information. In principle, photonic or electronic excitation of anisotropic films should result in polarized light emission. Because of spontaneous molecular self-assembly, liquid crystals are ideal for the exploration of polarized luminescence. Although most studies on polarized luminescence have been based on liquid crystalline fluid films, solid films are preferred in view of morphological stability. Therefore, the theme of my thesis is the study of polarized luminescence from various fluorescent liquid crystal systems. From the fundamental perspective, a theory modeling the process of polarized photoluminescence was validated using fluorophore doped fluid liquid crystal films. To provide the morphological stability crucial to practical application, polarized fluorescence using vitrifiable and polymeric liquid crystals functionalized with fluorescent moieties was investigated. In addition, liquid crystalline π- conjugated polymers were synthesized and characterized as a new class of optical polymers. The effect of the emission source on achievable polarization from pyrene and carbazole systems was also elucidated. The main observations are as follows: (1) The observed degrees of polarization for all fluorescent liquid crystal systems were found to agree with the theories governing polarized fluorescence. (2) Low molar mass vitrifiable and polymeric liquid crystalline cyanoterphenyl and cyanotolane derivatives were found to yield moderate polarized fluorescence. Monomer emission was established as the decay pathway for the precursors and cyclohexane and polymethacrylate derivatives. (3) Ordered solid films from thiophene and p-phenylene π-conjugated polymers were found to induce significant degrees of polarized fluorescence. (4) Emission from glass-forming pyrenyl derivatives exhibited excimer emission in dilute solution and neat film, whereas in solid hosts it was

  18. Enormous enhancement of ZnO nanorod photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.H.; Duan, W.J. [Department of Physics, Beijing Normal University, Beijing 100875 (China); Wu, Z.L.; Zheng, D. [Analytic and Testing Center, Beijing Normal University, Beijing 100875 (China); Zhou, X.W.; Zhou, B.Y.; Dai, L.J. [Department of Physics, Beijing Normal University, Beijing 100875 (China); Wang, Y.S., E-mail: yswang@bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    2012-08-15

    ZnO nanorod arrays were grown on quartz slices in the aqueous solution of zinc acetate and hexamethylenetetramine at 90 Degree-Sign 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: Black-Right-Pointing-Pointer ZnO nanorod arrays were grown on quartz slices in solution at 90 Degree-Sign C. Black-Right-Pointing-Pointer The nanorods were capped by ZnO:Mg layers to form core/shell structures. Black-Right-Pointing-Pointer ZnO:MgO shells suppress the green emission and enhance the UV emission intensity by 38 times. Black-Right-Pointing-Pointer The enhancement depends on the Mg content in the shells. Black-Right-Pointing-Pointer Exposing the nanorods to 325 laser beam improves the UV emission efficiently. Black-Right-Pointing-Pointer Capping and 325 nm laser beam irradiation could enhance the nanorod UV emission intensity by 71 times.

  19. Hollow waveguides with low intrinsic photoluminescence fabricated with Ta2O5 and SiO2 films

    OpenAIRE

    Zhao, Y.; Jenkins, M; Measor, P.; Leake, K.; Liu, S.; Schmidt, H.; Hawkins, A R

    2011-01-01

    A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with Ta2O5 and SiO2 films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition SiO2 and sputtered Ta2O5 provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using Si3N4, the photoluminescence background...

  20. Modeling of ballistic and trapping effects on the collection efficiency of holes and electrons separately for a planar mercuric iodide detector (HgI2

    Directory of Open Access Journals (Sweden)

    Cedric E. Beogo

    2016-07-01

    Full Text Available For the room temperature nuclear detector application, signal created in the detector depends not only to the energy of the incident photon but also to the position of the interaction. This can bring an incomplete charge collection caused by a deep-trapping or a ballistic deficit of charge carrier. Many scientists used to demonstrate their impact on the global efficiency of the charge collection. Here we show this effect, not globally but separately, according to the position where holes and electrons are created. It permits us to see the contribution of each kind of carrier in the signal formation. An analytical model of charge collection is developed firstly to take into account the deep-trapping only. Secondly, this model is improved adding the ballistic deficit effect. The deep-trapping contributes to reduce the efficiency of hole above all on thicker detector. In the other part, ballistic deficit reduce electron efficiency above all near anode in the negatively polarized detector.

  1. Photoluminescence enhancement in porous SiC passivated by atomic layer deposited Al2O3 films

    DEFF Research Database (Denmark)

    Lu, Weifang; Iwasa, Yoshimi; Ou, Yiyu

    2016-01-01

    Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved.......Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved....

  2. Size-independent peak shift between normal and upconversion photoluminescence in MPA-capped CdTe nanoparticles

    Indian Academy of Sciences (India)

    S Ananthakumar; J Jayabalan; Asha Singh; Salahuddin Khan; Subhash Prajapati; S Moorthy Babu; Rama Chari

    2014-02-01

    In this article, we report size-dependent measurement of the shift in peak of upconversion photoluminescence spectra compared to that of normal photoluminescence using a 800 nm femtosecond laser and its second harmonic. It has been shown that the upconversion photoluminescence is always red-shifted compared to that of normal PL in all the samples. By measuring the power-dependent upconversion photoluminescence (UCPL), it has been shown that the origin of UCPL from MPA-capped CdTe nanoparticles is mainly of two-photon absorption

  3. Reversible photoluminescence quenching of CdSe/ZnS quantum dots embedded in porous glass by ammonia vapor.

    Science.gov (United States)

    Orlova, A O; Gromova, Yu A; Maslov, V G; Andreeva, O V; Baranov, A V; Fedorov, A V; Prudnikau, A V; Artemyev, M V; Berwick, K

    2013-08-23

    The photoluminescence response of semiconductor CdSe/ZnS quantum dots embedded in a borosilicate porous glass matrix to exposure to ammonia vapor is investigated. The formation of surface complexes on the quantum dots results in quenching of the photoluminescence and a shortening of the luminescence decay time. The process is reversible, desorption of ammonia molecules from the quantum dot surface causes the photoluminescence to recover. The sensitivity of the quantum dot luminescence intensity and decay time to the interaction time and the reversibility of the photoluminescence changes make the CdSe/ZnS quantum dots in porous glass system a candidate for use as an optical sensor of ammonia.

  4. Reversible photoluminescence quenching of CdSe/ZnS quantum dots embedded in porous glass by ammonia vapor

    Science.gov (United States)

    Orlova, A. O.; Gromova, Yu A.; Maslov, V. G.; Andreeva, O. V.; Baranov, A. V.; Fedorov, A. V.; Prudnikau, A. V.; Artemyev, M. V.; Berwick, K.

    2013-08-01

    The photoluminescence response of semiconductor CdSe/ZnS quantum dots embedded in a borosilicate porous glass matrix to exposure to ammonia vapor is investigated. The formation of surface complexes on the quantum dots results in quenching of the photoluminescence and a shortening of the luminescence decay time. The process is reversible, desorption of ammonia molecules from the quantum dot surface causes the photoluminescence to recover. The sensitivity of the quantum dot luminescence intensity and decay time to the interaction time and the reversibility of the photoluminescence changes make the CdSe/ZnS quantum dots in porous glass system a candidate for use as an optical sensor of ammonia.

  5. Light absorption and photoluminescence due to interfacial charge-transfer transitions in aromatic amine-functionalized silicon nanoparticles

    Science.gov (United States)

    Fujisawa, Jun-ichi; Hanaya, Minoru

    2017-09-01

    Aromatic amine-functionalization of silicon nanoparticles induces a new absorption band in the near UV-to-blue region and efficient blue photoluminescence even at room temperature. However, the origin of the absorption band and photoluminescence has not yet been understood well. Here, we study theoretically the electronic structure and light absorption and photoluminescence properties of carbazole-functionalized silicon nanoparticles. We reveal that the absorption band and photoluminescence are attributed to interfacial charge-transfer (ICT) transitions between the covalently-boned carbazole and silicon nanoparticles. The ICT transitions are induced by strong electronic couplings between CA and a silicon nanoparticle via the Sisbnd N bond.

  6. Photoluminescence enhancement in porous SiC passivated by atomic layer deposited Al2O3 films

    DEFF Research Database (Denmark)

    Lu, Weifang; Iwasa, Yoshimi; Ou, Yiyu;

    2016-01-01

    Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved.......Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved....

  7. Photoluminescence properties of cadmium-selenide quantum dots embedded in a liquid-crystal polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tselikov, G. I., E-mail: gleb@vega.phys.msu.ru; Timoshenko, V. Yu. [Moscow State University, Faculty of Physics (Russian Federation); Plenge, J.; Ruehl, E. [Free University of Berlin, Institute of Chemistry and Biochemistry (Germany); Shatalova, A. M.; Shandryuk, G. A.; Merekalov, A. S.; Tal' roze, R. V. [Russian Academy of Sciences, Topchiev Institute of Petrochemical Synthesis (Russian Federation)

    2013-05-15

    The photoluminescence properties of cadmium-selenide (CdSe) quantum dots with an average size of {approx}3 nm, embedded in a liquid-crystal polymer matrix are studied. It was found that an increase in the quantum-dot concentration results in modification of the intrinsic (exciton) photoluminescence spectrum in the range 500-600 nm and a nonmonotonic change in its intensity. Time-resolved measurements show the biexponential decay of the photoluminescence intensity with various ratios of fast and slow components depending on the quantum-dot concentration. In this case, the characteristic lifetimes of exciton photoluminescence are 5-10 and 35-50 ns for the fast and slow components, respectively, which is much shorter than the times for colloidal CdSe quantum dots of the same size. The observed features of the photoluminescence spectra and kinetics are explained by the effects of light reabsorption, energy transfer from quantum dots to the liquid-crystal polymer matrix, and the effect of the electronic states at the CdSe/(liquid crystal) interface.

  8. Photoluminescence as a Probe of the Electrical Charge Dependence of Gold Nanoparticles.

    Science.gov (United States)

    Obradovic, M; Di Vece, M; Asselberghs, I; Grandjean, D; Clays, K; Lievens, P

    2015-12-01

    Electro-optical switching can be achieved by changing the optical absorption of metal nanoparticles by adding or removing electrical charge, corresponding to increased, respectively, decreased electron density. In this work a different approach is taken by changing the photoluminescence properties as a function of electrical charge on gold nanoparticles. Whereas larger gold nanoparticles (diameter d = 5 and 10 nm), exhibiting a plasmon resonance peak in the absorption spectrum, were used to measure changes of the optical absorption spectrum upon electrical charging, for smaller gold nanoparticles (d = 2 and 5 nm) electrical charging was observed via changes of the photoluminescence. Increase and decrease in photoluminescence was observed at positive and negative applied potentials, respectively. The relation between changes of optical absorption and photoluminescence for the 5 nm particles by electrical charging provides information on the influence of the charge state on the electronic properties and therefore the optical transition probability. The reported observation that not only the optical absorption, but also the photoluminescence is affected by alteration of the electrical charge onto gold nanoparticles may open a new way towards electro-optical switching and bio-sensing.

  9. Two-photon induced photoluminescence and singlet oxygen generation from aggregated gold nanoparticles.

    Science.gov (United States)

    Jiang, Cuifeng; Zhao, Tingting; Yuan, Peiyan; Gao, Nengyue; Pan, Yanlin; Guan, Zhenping; Zhou, Na; Xu, Qing-Hua

    2013-06-12

    Metal nanoparticles have potential applications as bioimaging and photosensitizing agents. Aggregation effects are generally believed to be adverse to their biomedical applications. Here we have studied the aggregation effects on two-photon induced photoluminescence and singlet oxygen generation of Au nanospheres and Au nanorods of two different aspect ratios. Aggregated Au nanospheres and short Au nanorods were found to display enhanced two-photon induced photoluminescence and singlet oxygen generation capabilities compared to the unaggregated ones. The two-photon photoluminescence of Au nanospheres and short Au nanorods were enhanced by up to 15.0- and 2.0-fold upon aggregation, and the corresponding two-photon induced singlet oxygen generation capabilities were enhanced by 8.3 and 1.8-fold, respectively. The two-photon induced photoluminescence and singlet oxygen generation of the aggregated long Au nanorods were found to be lower than the unaggregated ones. These results support that the change in their two-photon induced photoluminescence and singlet oxygen generation originate from aggregation modulated two-photon excitation efficiency. This finding is expected to foster more biomedical applications of metal nanoparticles as Au nanoparticles normally exist in an aggregated form in the biological environments. Considering their excellent biocompatibility, high inertness, ready conjugation, and easy preparation, Au nanoparticles are expected to find more applications in two-photon imaging and two-photon photodynamic therapy.

  10. High-temperature photoluminescence of CdSe/CdS core/shell nanoheterostructures.

    Science.gov (United States)

    Diroll, Benjamin T; Murray, Christopher B

    2014-06-24

    The steady-state and time-resolved photoluminescence properties of CdSe/CdS heterostructures are studied as a function of temperature from 300 to 600 K. The emission properties of samples are found to behave similarly to bulk CdSe, with the samples maintaining high color purity and a slightly contracting band gap at elevated temperature. Photoluminescence from CdSe/CdS samples is maintained with high stability over prolonged illumination and multiple heating and cooling cycles. Structures synthesized with variation in the core and the shell dimensions show that the preservation of emission intensity at high temperature depends strongly on the microscopic structure of the samples. For samples synthesized by seeded growth, the size of the CdSe core is highly correlated with the fraction of preserved sample photoluminescence intensity at high temperature. Temperature-dependent lifetime data suggest that the core structure predicts the stability of photoluminescence at elevated temperatures by controlling the radiative rate. The rate of electron capture, for which the volume fraction of the core is a structural proxy, underpins the ability for radiative processes to compete with thermally induced nonradiative decay pathways. Heterostructures synthesized below 200 °C using highly reactive organometallic precursors show markedly lower thermal stability than samples prepared by seeded growth at 360 °C, suggesting that the temperature of nanocrystal synthesis has direct consequences for the thermal stability of photoluminescence.

  11. Reduction of Photoluminescence Quenching by Deuteration of Ytterbium-Doped Amorphous Carbon-Based Photonic Materials.

    Science.gov (United States)

    Hsu, Hui-Lin; Leong, Keith R; Teng, I-Ju; Halamicek, Michael; Juang, Jenh-Yih; Jian, Sheng-Rui; Qian, Li; Kherani, Nazir P

    2014-08-06

    In situ Yb-doped amorphous carbon thin films were grown on Si substrates at low temperatures (photoluminescence around 1 µm was observed via direct incorporation of optically active Yb(3+) ions from the selected Yb(fod)₃ metal-organic compound. The partially fluorinated Yb(fod)₃ compound assists the suppression of photoluminescence quenching by substitution of C-H with C-F bonds. A four-fold enhancement of Yb photoluminescence was demonstrated via deuteration of the a-C host. The substrate temperature greatly influences the relative deposition rate of the plasma dissociated metal-organic species, and hence the concentration of the various elements. Yb and F incorporation are promoted at lower substrate temperatures, and suppressed at higher substrate temperatures. O concentration is slightly elevated at higher substrate temperatures. Photoluminescence was limited by the concentration of Yb within the film, the concentration of Yb ions in the +3 state, and the relative amount of quenching due to the various de-excitation pathways associated with the vibrational modes of the host a-C network. The observed wide full-width-at-half-maximum photoluminescence signal is a result of the variety of local bonding environments due to the a-C matrix, and the bonding of the Yb(3+) ions to O and/or F ions as observed in the X-ray photoelectron spectroscopy analyses.

  12. 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.

  13. Erbium photoluminescence response related to nanoscale heterogeneities in sol-gel silicates

    Institute of Scientific and Technical Information of China (English)

    H.C.Vasconcelos; M.G.Meirelles; F.Rivera-López

    2013-01-01

    Sol-gel glassy films of the SiO2-TiO2-PO2.5-ErO2.5 system containing nanocrystallites of ErPO4,were obtained through suitable heat treatments.Variations in the shape and intensity of the Er3+ photoluminescent signal around 1500 nm were linked to the nature of the host environment of the active ions; the specific features of the photoluminescent emission spectrum of the erbium 4113/2 metastable level were interpreted in terms of structural changes in the glassy films.The photoluminescent spectrum was found to be sensitive to the order (crystalline) or disorder (amorphous) of the Er3+ ions neighbour within the glassy matrix.An amorphous environment led to a broadening of Er3+ PL emission band while a crystalline one was responsible for a drastic photoluminescent bandwidth narrowing.The presence of nanoscale heterogeneities caused a drastic photoluminescence intensity decrease.Changes in the shape of the decay curve of fluorescence lifetime were found also structurally dependent on volumetric defects,occurrence of phase separation and Er3+-Er3+ clustering effects as well.

  14. Hole scavenging and aging effect on the photoluminescence of CdS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manoj K., E-mail: mksingh@barc.gov.in [Atomic and Molecular Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Hassan, P.A. [Chemistry Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Kadam, Anita [Atomic and Molecular Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India)

    2014-07-01

    On photoexcitation the excited state of colloidal quantum dots usually exhibit multi-exponential decay with long lifetime due to mixing of a number of excitonic and surface states. However, during present investigation the luminescence decay from CdS quantum dots stabilized by sodium dodecyl sulphate (SDS) follows single exponential decay function. Photoluminescence from these (particle size ∼ 3.0 nm) quantum dots originate from the trap-state (λ{sub max} – 516 nm) and exhibit mono-exponential decay with a time constant of 1.7 ns. The hole scavenging characteristics of SDS seems to be instrumental in controlling the decay kinetics of these nanoparticles. On aging band-edge emission peak appears in the lower wavelength region at ∼410 nm and the time-resolved photoluminescence fits to a bi-exponential decay function. The photoluminescence excitation and 3D-luminescence spectroscopic analysis suggests that both band-edge and trap-state emissions from aged samples are associated with the same species. Change in the emission spectra on aging occurs due to self-surface passivation of defects by sulphide ions. - Highlights: • Aqueous route synthesis of SDS stabilized CdS quantum dots to restrict emission behaviour. • Single exponential decay of photoluminescence controlled by hole scavenger SDS. • Due to self surface passivation the photoluminescence behaviour changes on aging.

  15. Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties.

    Science.gov (United States)

    Rausch, Janek; Lorenz, Volker; Hrib, Cristian G; Frettlöh, Vanessa; Adlung, Matthias; Wickleder, Claudia; Hilfert, Liane; Jones, Peter G; Edelmann, Frank T

    2014-11-03

    This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.

  16. 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.

  17. Niobium-gallium oxide with a high concentration of Cr3+ ions: Photoluminescence and structural characteristics

    Science.gov (United States)

    Costa, G. K. B.; Pedro, S. S.; López, A.; Carvalho, I. C. S.; Cella, N.; Sosman, L. P.

    2016-10-01

    This work presents photoluminescence data for gallium-niobium oxide with chromium ion as an impurity. The samples were obtained by the solid-state method (SSM) and the wet-chemical method (WCM) and investigated by X-ray diffraction, photoluminescence, excitation, and photoacoustic and X-ray fluorescence. The color of the sample obtained by the SSM was pink, while the color of the sample prepared by the WCM was green. This dramatic difference was associated with Cr3+ concentration and with the neighborhood of the doping ions, obtained from crystallographic data, which is strongly dependent on the preparation method. The difference between the samples was also verified in the photoacoustic and excitation spectra, in which the energy bands were located at different energy levels; on the other hand, in the photoluminescence spectra, no band shift was observed. All spectra were assigned to chromium ions at nonequivalent octahedral sites.

  18. 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.

  19. Photoluminescent behavior of heat-treated porous alumina films formed in malonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Vrublevsky, I., E-mail: vrublevsky@bsuir.edu.by [Department of Micro and Nanoelectronics, Belarusian State University of Informatics and Radioelectronics, 6 Brovka str, Minsk 220013 (Belarus); Jagminas, A. [Institute of Chemistry, A.Gostauto 9, LT-01108 Vilnius (Lithuania); Hemeltjen, S.; Goedel, W.A. [Institut fuer Chemie, Technische Universitaet Chemnitz, D-09107 (Germany)

    2010-01-15

    In the present work IR spectroscopy, electron probe microanalysis (EPMA) and photoluminescence (PL) spectral measurements were applied to study the effect of treatment temperature (T) on compositional and luminescent properties of malonic acid alumina films. Our studies have shown that the heat treatment of anodic alumina films at investigated temperatures from 100 up to 700 deg. C changes their photoluminescence spectra considerably. An increase in T results in the PL intensity growth. When reaching its maximum at 600 deg. C the luminescence intensity then decreases drastically with further T growth. The films heat-treated at 500 and 600 deg. C demonstrate asymmetrical PL band with Gaussian peaks at 437 and 502 nm. We proved that the malonic acid species incorporated into the alumina bulk during the film formation are responsible for photoluminescence band with its peak at 437 nm.

  20. Photoluminescence spectroscopy investigation of epitaxial Si/GaSb nanocrystals/Si heterostructure

    Science.gov (United States)

    Goroshko, Dmitry L.; Shevlyagin, Alexander V.; Chusovitin, Evgeniy A.; Dotsenko, Sergey A.; Gutakovskii, Anton K.; Iinuma, M.; Terai, Y.; Subbotin, Evgeniy Yu.; Galkin, Nikolay G.

    2017-09-01

    Two-layer heterostructure with GaSb nanocrystals formed by solid phase epitaxy and embedded into the silicon was investigated using low-temperature (10-140 K) photoluminescence and time-resolved photoluminescence spectroscopies. Two characteristic luminescence bands with a maximum of about 0.82 and 0.87 eV were observed. It was found that low-energy peak is associated with D1 dislocation-related luminescence in silicon. Analysis of the decay components together with temperature and power dependencies of the photoluminescence for the high-energy maximum revealed that emission is more likely originated from the combined D2 dislocation centers in silicon and radiative recombination in type-II band alignment Si/GaSb nanocrystals/Si heterostructure. A nonradiative recombination dominates in all temperature range studied.

  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. 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.

  3. Control of Photoluminescence of Carbon Nanodots via Surface Functionalization using Para-substituted Anilines

    Science.gov (United States)

    Kwon, Woosung; Do, Sungan; Kim, Ji-Hee; Seok Jeong, Mun; Rhee, Shi-Woo

    2015-01-01

    Carbon nanodots (C-dots) are a kind of fluorescent carbon nanomaterials, composed of polyaromatic carbon domains surrounded by amorphous carbon frames, and have attracted a great deal of attention because of their interesting properties. There are still, however, challenges ahead such as blue-biased photoluminescence, spectral broadness, undefined energy gaps and etc. In this report, we chemically modify the surface of C-dots with a series of para-substituted anilines to control their photoluminescence. Our surface functionalization endows our C-dots with new energy levels, exhibiting long-wavelength (up to 650 nm) photoluminescence of very narrow spectral widths. The roles of para-substituted anilines and their substituents in developing such energy levels are thoroughly studied by using transient absorption spectroscopy. We finally demonstrate light-emitting devices exploiting our C-dots as a phosphor, converting UV light to a variety of colors with internal quantum yields of ca. 20%. PMID:26218869

  4. On the nature of photoluminescence in Bismuth-doped silica glass.

    Science.gov (United States)

    Laguta, Oleksii V; Hamzaoui, Hicham El; Bouazaoui, Mohamed; Arion, Vladimir B; Razdobreev, Igor M

    2017-06-09

    We report on the investigation of Bismuth-doped pure silica glass without other co-dopant by the tech- nique of magnetic circular dichroism (MCD), which allows the direct probing of the ground state of optical centres. Taking into account the results of conventional optical spectroscopy, we show that the observed MCD bands belong to the centre responsible for the red photoluminescence in this material. Measurements of the temperature and field dependences indicate that the MCD effect is caused by the even-electron system. This, however, opposes the widespread opinion that Bi(2+) ions are the origin of red photoluminescence in Bismuth-doped silica glasses. On the other hand, the lasing centre responsi- ble for the near infrared photoluminescence does not exhibit any magnetic optical activity connected to its ground state. As a consequence, we conclude that the ground state of lasing centre is a magnetic singlet with the effective spin S = 0.

  5. Efficient near-infrared up-conversion photoluminescence in carbon nanotubes

    Science.gov (United States)

    Akizuki, Naoto; Aota, Shun; Mouri, Shinichiro; Matsuda, Kazunari; Miyauchi, Yuhei

    2015-01-01

    Photoluminescence phenomena normally obey Stokes' law of luminescence according to which the emitted photon energy is typically lower than its excitation counterparts. Here we show that carbon nanotubes break this rule under one-photon excitation conditions. We found that the carbon nanotubes exhibit efficient near-infrared photoluminescence upon photoexcitation even at an energy lying >100–200 meV below that of the emission at room temperature. This apparently anomalous phenomenon is attributed to efficient one-phonon-assisted up-conversion processes resulting from unique excited-state dynamics emerging in an individual carbon nanotube with accidentally or intentionally embedded localized states. These findings may open new doors for energy harvesting, optoelectronics and deep-tissue photoluminescence imaging in the near-infrared optical range. PMID:26568250

  6. Photoluminescence quantum efficiency of Er optical centers in GaN epilayers.

    Science.gov (United States)

    Ho, V X; Dao, T V; Jiang, H X; Lin, J Y; Zavada, J M; McGill, S A; Vinh, N Q

    2017-01-05

    We report the quantum efficiency of photoluminescence processes of Er optical centers as well as the thermal quenching mechanism in GaN epilayers prepared by metal-organic chemical vapor deposition. High resolution infrared spectroscopy and temperature dependence measurements of photoluminescence intensity from Er ions in GaN under resonant excitation excitations were performed. Data provide a picture of the thermal quenching processes and activation energy levels. By comparing the photoluminescence from Er ions in the epilayer with a reference sample of Er-doped SiO2, we find that the fraction of Er ions that emits photon at 1.54 μm upon a resonant optical excitation is approximately 68%. This result presents a significant step in the realization of GaN:Er epilayers as an optical gain medium at 1.54 μm.

  7. Pulsed laser deposited LaInO{sub 3} thin films and their photoluminescence characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Chaluvadi, Sandeep Kumar [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Centre for Nanotechnology Research, SENSE, VIT University, Vellore, Tamil Nadu 632014 (India); Aswin, V.; Kumar, Pramod; Singh, Pooja; Haranath, D.; Rout, P.K. [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Dogra, Anjana, E-mail: anjanad@nplindia.org [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2015-10-15

    Photoluminescence studies of pulsed laser deposition grown LaInO{sub 3} thin films on TiO{sub 2} terminated SrTiO{sub 3} substrate showed a broad-band blue emission peaking at 412 nm, which is primarily attributed to the charge transfer transitions between oxygen and indium, inter (d–f) and intra (f–f) band transitions. The results are analysed based on the mechanism of absorption and emission within the d{sup 10} levels of In{sup 3+} ions. Broadening of the photoluminescence emission is observed with reduction in size of the crystallite owing to quantum confinement effects. - Highlights: • First time grown thin films of LaInO{sub 3} by PLD. • Interesting new photoluminescence features in thin films of LaInO{sub 3}. • Results are discussed on the basis of quantum confinement.

  8. UV and air stability of high-efficiency photoluminescent silicon nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jihua, E-mail: yangj@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Liptak, Richard [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Ave, Terre Haute, IN 47803 (United States); Rowe, David; Wu, Jeslin [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Casey, James; Witker, David [Dow Corning Corporation, 2200 W. Salzburg Road, Midland, MI 48686 (United States); Campbell, Stephen A. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Kortshagen, Uwe, E-mail: kortshagen@umn.edu [Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455 (United States)

    2014-12-30

    The effects of UV light and air exposure on the photoluminescent properties of nonthermal plasma-synthesized silicon nanocrystals (Si NCs) were investigated. Si NCs with high-efficiency photoluminescence (PL) have been achieved via a post-synthesis hydrosilylation process. Photobleaching is observed within the first few hours of ultra-violet (UV) irradiation. Equilibrium is reached after ∼4 h of UV exposure wherein the Si NCs are able to retain 52% of the initially measured PL quantum yield (PLQY). UV-treated Si NCs showed recovery of PL with time. Gas-phase passivation of Si NCs by hydrogen afterglow injection improves PLQY and PL stability against UV and air exposure. Additionally, phosphorous doping can also improve UV stability of photoluminescent Si NCs.

  9. Lattice Disorder and Photoluminescence of Er-Implanted A1N Crystalline Films

    Institute of Scientific and Technical Information of China (English)

    卢霏; A.Rizzi; R.Carius

    2002-01-01

    AlN crystalline films have been grown on SiC substrates by molecular beam epitaxy. Er doping was carried out by implantation with energy 180keV to fluence of 1 × 1015 ions/cm2. The as-implanted samples were then annealed at 650, 800, 950 and 1100.C respectively, to remove defects and to make Er ions optically active. The annealing up to 1100.C did not exert significant influence on either Er distribution or the profiles of implant-induced lattice damage. Strong 1.54 μm photoluminescence was observed in Er-implanted A1N at room temperature. The experimental results indicate that the photoluminescence lifetime can be improved by increasing the annealing temperature. The maximum photoluminescence lifetime was measured to be 2.3ms.

  10. Elucidating Quantum Confinement in Graphene Oxide Dots Based On Excitation-Wavelength-Independent Photoluminescence.

    Science.gov (United States)

    Yeh, Te-Fu; Huang, Wei-Lun; Chung, Chung-Jen; Chiang, I-Ting; Chen, Liang-Che; Chang, Hsin-Yu; Su, Wu-Chou; Cheng, Ching; Chen, Shean-Jen; Teng, Hsisheng

    2016-06-02

    Investigating quantum confinement in graphene under ambient conditions remains a challenge. In this study, we present graphene oxide quantum dots (GOQDs) that show excitation-wavelength-independent photoluminescence. The luminescence color varies from orange-red to blue as the GOQD size is reduced from 8 to 1 nm. The photoluminescence of each GOQD specimen is associated with electron transitions from the antibonding π (π*) to oxygen nonbonding (n-state) orbitals. The observed quantum confinement is ascribed to a size change in the sp(2) domains, which leads to a change in the π*-π gap; the n-state levels remain unaffected by the size change. The electronic properties and mechanisms involved in quantum-confined photoluminescence can serve as the foundation for the application of oxygenated graphene in electronics, photonics, and biology.

  11. Radiative and non-radiative recombinations in tensile strained Ge microstrips: Photoluminescence experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Virgilio, M., E-mail: virgilio@df.unipi.it [Dip. di Fisica “E. Fermi,” Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); NEST, Istituto Nanoscienze-CNR, P.za San Silvestro 12, 56127 Pisa (Italy); Schroeder, T.; Yamamoto, Y. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Dip. di scienze, Università Roma Tre, viale G. Marconi 446, 00146 Roma (Italy)

    2015-12-21

    Tensile germanium microstrips are candidate as gain material in Si-based light emitting devices due to the beneficial effect of the strain field on the radiative recombination rate. In this work, we thoroughly investigate their radiative recombination spectra by means of micro-photoluminescence experiments at different temperatures and excitation powers carried out on samples featuring different tensile strain values. For sake of comparison, bulk Ge(001) photoluminescence is also discussed. The experimental findings are interpreted in light of a numerical modeling based on a multi-valley effective mass approach, taking in to account the depth dependence of the photo-induced carrier density and of the self-absorption effect. The theoretical modeling allowed us to quantitatively describe the observed increase of the photoluminescence intensity for increasing values of strain, excitation power, and temperature. The temperature dependence of the non-radiative recombination time in this material has been inferred thanks to the model calibration procedure.

  12. Piezoelectric/photoluminescence effects in rare-earth doped lead-free ceramics

    Science.gov (United States)

    Yao, Qirong; Wang, Feifei; Jin, Chengchao; Tang, Yanxue; Wang, Tao; Shi, Wangzhou

    2013-10-01

    In the present work, we report the environmentally-friendly multifunctional effects—piezoelectric/photoluminescence effects, which originated from the combination of the electromechanical properties and the photoluminescence effect through introducing the rare-earth elements (Pr and Eu) into the (Bi0.5Na0.5)TiO3-BaTiO3 ceramics with the composition around the morphotropic phase boundary. Compared to the pure piezoelectric ceramic, the proposed system simultaneously exhibited enhanced ferroelectric, piezoelectric, dielectric properties along with strong photoluminescence effects, which exhibited potential applications in sensor, and electro-mechano-optical integration. In addition, the present work also provides a promising path for us to fabricate multifunctional composites.

  13. Enhancing photoluminescence yields in lead halide perovskites by photon recycling and light out-coupling

    Science.gov (United States)

    Richter, Johannes M.; Abdi-Jalebi, Mojtaba; Sadhanala, Aditya; Tabachnyk, Maxim; Rivett, Jasmine P. H.; Pazos-Outón, Luis M.; Gödel, Karl C.; Price, Michael; Deschler, Felix; Friend, Richard H.

    2016-12-01

    In lead halide perovskite solar cells, there is at least one recycling event of electron-hole pair to photon to electron-hole pair at open circuit under solar illumination. This can lead to a significant reduction in the external photoluminescence yield from the internal yield. Here we show that, for an internal yield of 70%, we measure external yields as low as 15% in planar films, where light out-coupling is inefficient, but observe values as high as 57% in films on textured substrates that enhance out-coupling. We analyse in detail how externally measured rate constants and photoluminescence efficiencies relate to internal recombination processes under photon recycling. For this, we study the photo-excited carrier dynamics and use a rate equation to relate radiative and non-radiative recombination events to measured photoluminescence efficiencies. We conclude that the use of textured active layers has the ability to improve power conversion efficiencies for both LEDs and solar cells.

  14. 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.

  15. Infrared photoluminescence from GeSi nanocrystals embedded in a germanium–silicate matrix

    Energy Technology Data Exchange (ETDEWEB)

    Volodin, V. A., E-mail: volodin@isp.nsc.ru; Gambaryan, M. P.; Cherkov, A. G.; Vdovin, V. I. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Stoffel, M.; Rinnert, H.; Vergnat, M. [Université de Lorraine, Institut Jean Lamour UMR CNRS 7198 (France)

    2015-12-15

    We investigate the structural and optical properties of GeO/SiO{sub 2} multilayers obtained by evaporation of GeO{sub 2} and SiO{sub 2} powders under ultrahigh vacuum conditions on Si(001) substrates. Both Raman and infrared absorption spectroscopy measurements indicate the formation of GeSi nanocrystals after postgrowth annealing at 800°C. High-resolution transmission electron microscopy characterizations show that the average size of the nanocrystals is about 5 nm. For samples containing GeSi nanocrystals, photoluminescence is observed at 14 K in the spectral range 1500–1600 nm. The temperature dependence of the photoluminescence is studied.

  16. Infrared photoluminescence from GeSi nanocrystals embedded in a germanium-silicate matrix

    Science.gov (United States)

    Volodin, V. A.; Gambaryan, M. P.; Cherkov, A. G.; Vdovin, V. I.; Stoffel, M.; Rinnert, H.; Vergnat, M.

    2015-12-01

    We investigate the structural and optical properties of GeO/SiO2 multilayers obtained by evaporation of GeO2 and SiO2 powders under ultrahigh vacuum conditions on Si(001) substrates. Both Raman and infrared absorption spectroscopy measurements indicate the formation of GeSi nanocrystals after postgrowth annealing at 800°C. High-resolution transmission electron microscopy characterizations show that the average size of the nanocrystals is about 5 nm. For samples containing GeSi nanocrystals, photoluminescence is observed at 14 K in the spectral range 1500-1600 nm. The temperature dependence of the photoluminescence is studied.

  17. 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 exci......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...

  18. Photoluminescence and Raman spectroscopy characterization of boron- and nitrogen-doped 6H silicon carbide

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Liu, Chuan

    2011-01-01

    Boron - and nitrogen-doped 6H silicon carbide epilayers grown on low off-axis 6H silicon carbide substrates have been characterized by photoluminescence and Raman spectroscopy. Combined with secondary ion mass spectrometry results, preferable doping type and optimized concentration could be propo......Boron - and nitrogen-doped 6H silicon carbide epilayers grown on low off-axis 6H silicon carbide substrates have been characterized by photoluminescence and Raman spectroscopy. Combined with secondary ion mass spectrometry results, preferable doping type and optimized concentration could...

  19. 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.

  20. 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.

  1. Instrumentation for Reliably Determining Porous Silicon Photoluminescence Responses to Gaseous Analyte Vapors.

    Science.gov (United States)

    Reynard, Justin M; Van Gorder, Nathan S; Richardson, Caley A; Eriacho, Richie D; Bright, Frank V

    2016-12-01

    We report new instrumentation for rapidly and reliably measuring the temperature-dependent photoluminescence response from porous silicon as a function of analyte vapor concentration. The new system maintains the porous silicon under inert conditions and it allows on-the-fly steady-state and time-resolved photoluminescence intensity and hyper-spectral measurements between 293 K and 450 K. The new system yields reliable data at least 100-fold faster in comparison to previous instrument platforms. © The Author(s) 2016.

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

    CERN Document Server

    Bray, Kerem; 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 suppresses 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

  3. Photoluminescence and Exciton Energy Transfer of A Novel Perylene-Containing Polyimide

    Institute of Scientific and Technical Information of China (English)

    Shengang Xu; Mujie Yang; Shaokui Cao

    2005-01-01

    @@ 1Introduction Peryleneimides are well known chromophores combining high quantum yields of photoluminescence with outstanding photochemical and thermal stability. Due to their useful electroactive and photoactive properties many potential applications in optoelectronics have attracted increasing interest.Previously, we reported a kind of diphenylfluorene-based cardo polyimide containing perylene units in the backbone[1,2], which possessed high thermal stability, excellent solubility and good film formability. In the present work, the photoluminescence and exciton energy transfer of this novel polyimide were reported.

  4. Synthesis and photoluminescence properties of Mn-doped ZnS nanobelts

    Institute of Scientific and Technical Information of China (English)

    CHEN Hai-yan; YANG Xiao-ling; HOU De-dong; LIU Ying-kai

    2009-01-01

    Mn-doped ZnS nanobelts have been prepared through a thermal evaporation method at 1100℃. The synthesized nanobelts are characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectroscopy. The results show that the nanobelts have an uniform single-crystal hexagonal wurtzite structure and grow along [0001] direction. Room-temperature photoluminescence reveals that the intrinsic PL of the nanobelts disappears and a new PL peak of the Mn-doped ZnS nanobelts emerges at 575 nm.

  5. 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.

  6. Bacterial spore detection and determination by use of terbium dipicolinate photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, D.L. [Army Research Lab., Adelphi, MD (United States); Sharpless, C.; McGown, L.B. [Duke Univ., Durham, NC (United States)

    1997-03-15

    A new method to detect bacterial endospores and determine their concentration was demonstrated by the addition of a solution of terbium chloride to a suspension of bacterial endospores. The terbium chloride reacted with the calcium dipicolinate in the spore case to form terbium(III) dipicolinate anion. Solid particles, including residual bacterial particles, were removed by filtering. The photoluminescence from the solution was measured as a function of excitation wavelength, emission wavelength, and bacterial endospore concentration. The photoluminescence from terbium(III) dipicolinate anion in the solution was easily identified. 15 refs., 5 figs.

  7. Enhanced photoluminescence from photonic crystal-coated GaN LED wafers

    Science.gov (United States)

    Rahman, F.; Khokhar, A. Z.

    2011-06-01

    This paper describes results of studies on photoluminescence from blue-emitting GaN LED wafers coated with a layer of synthetic opal photonic crystals. Commercial LED wafer material was used and samples were coated with thin films consisting of several layers of stacked spherical polystyrene balls. Various optical measurements were performed on these samples while they were excited with a 405 nm laser beam. Diffraction pattern due to the photonic crystal structure, showing the underlying six-fold symmetry, was recorded. The spectrum and angle-resolved intensity of photoluminescence were measured to understand the coupling of LED light with the grown photonic crystal structure on top of the wafer.

  8. Improved photoluminescence of silicon nanocrystals in silicon nitride prepared by ammonia sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ma, K; Feng, J Y; Zhang, Z J [Department of Materials Science and Engineering, Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084 (China)

    2006-09-28

    In the present work we investigated the photoluminescence property of silicon nanocrystals in silicon nitride prepared by ammonia sputtering. Silicon nanocrystals were demonstrated to form even after thermal annealing at 700 deg. C. Compared with the control sample using N{sub 2} as the reactive gas, the luminescence intensity of silicon nanocrystals in silicon nitride prepared by NH{sub 3} sputtering was greatly increased. The improvement in photoluminescence was attributed to the introduction of hydrogen-related bonds, which could well passivate the nonradiative defects existing at the interface between silicon nanocrystals and the silicon nitride matrix.

  9. On the nature of the stretched exponential photoluminescence decay for silicon nanocrystals

    Directory of Open Access Journals (Sweden)

    Cardin J

    2011-01-01

    Full Text Available Abstract The influence of hydrogen rate on optical properties of silicon nanocrystals deposited by sputtering method was studied by means of time-resolved photoluminescence spectroscopy as well as transmission and reflection measurements. It was found that photoluminescence decay is strongly non-single exponential and can be described by the stretched exponential function. It was also shown that effective decay rate probability density function may be recovered by means of Stehfest algorithm. Moreover, it was proposed that the observed broadening of obtained decay rate distributions reflects the disorder in the samples.

  10. Tip-enhanced photoluminescence mapping of InGaN thin film

    Science.gov (United States)

    Katayama, K.; Ogawa, Y.; Minami, F.

    2011-01-01

    The photoluminescence from localized excitons in In 0.25Ga 0.75N was enhanced up to 6.6 times by approaching a gold nano-particle to nano-meter vicinity. Mapping images of enhanced photoluminescence and topological images were measured simultaneously with a spatial resolution of 100 nm. With an improved measurement system and selection of relatively flat area of the sample, we propose that the segregated metallic In droplet ought to play an important role for the present tip-enhance effect.

  11. Application of the generalized Kirchhoff's law to calculation of photoluminescence spectra of one-dimensional photonic crystals

    CERN Document Server

    Voronov, Mikhail M

    2016-01-01

    The approach based on the generalized Kirchhoff's law for calculating photoluminescence spectra of one-dimensional multi-layered structures, in particular, 1D photonic crystals has been developed. It is valid in the local thermodynamic equilibrium approximation and leads to simple and explicit expressions for the photoluminescence intensity. In the framework of the present theory the Purcell factor has been discussed as well.

  12. Mechanoluminescence by Impulsive Deformation and Photoluminescence of SrAl2O4:Eu Phosphor Prepared by Combustion Synthesis

    Science.gov (United States)

    Choubey, Anil Kumar; Brahme, Nameeta; Bisen, D. P.

    SrAl2O4: Eu was synthesized by combustion method. Mechanoluminescence (ML) and Photoluminescence (PL) were studied. Time vs ML intensity plot shows two peaks. ML intensity increases with load applied and it is regained by UV irradiation. Photoluminescence shows intense emission in green region. PACS: 78.60.Mq; 78.55.Hx

  13. Spin Polarization Effects in the Photoluminescence of Polythiophene.

    Science.gov (United States)

    Hess, Bret Clark

    Photoluminescence (PL), optically detected magnetic resonance (ODMR), and nonresonant magnetic field effects (NFE) have been studied in polythiophene (PT) and poly(3 -alkylthiophene) (P3AT). The PT samples studied were chemically coupled PT (c-PT) and electrochemically coupled PT (e-PT); the P3AT samples were poly(3-hexylthiophene) (HPT) and a copolymer of 3-benzylthiophene and 3-hexylthiophene (BHPT). The PL spectra of PT and P3AT exhibit a broad band centered between 1.6-1.9 eV, a narrow peak at 1.8 -1.95 eV, and 0.18 eV phonon replicas of the narrow peak. The PL spectrum of e-PT is similar to the published spectra, while the PL of c-PT is dominated by a broad band centered near 1.6-1.7 eV, in contrast to previously published results. HPT and BHPT show almost identical PL spectra. In all samples, the integrated PL intensity is nearly temperature independent. ODMR was measured at X-band from 5 to 300K. Strong PL-enhancing signals (DeltaL/L ~eq 2 times 10 ^{-3} at low temperatures) were detected at g = 2.003. The strength of the signal and its temperature dependence suggest that the ODMR probes unthermalized spins. In c-PT, the ODMR originates from a broad structureless PL band which is devoid of the phonon sidebands and is centered near 1.65 eV. The ODMR in each sample is composed of two components separated by Deltag ~eq 6 times 10^{-4}. Although these two components are tentatively assigned to recombining positive and negative polarons, the possibility of two distinct long lived recombination mechanisms cannot be excluded. The ODMR signal decreases with increasing modulation frequency. The cutoff frequencies indicate that in addition to the well known fast PL, long PL lifetimes (10 ^{-5} to 10^{ -3} sec) are present in these samples. The PL in P3AT appears to contain the longest lived component. Magnetic fields from 0 to 700 G cause broad enhancing and quenching changes in the PL intensity. The NFE in c-PT shows sharp peaks at 110 and 220 G. P3AT also shows a

  14. Optical properties of InGaAsBi/GaAs strained quantum wells studied by temperature-dependent photoluminescence

    Institute of Scientific and Technical Information of China (English)

    GU Yi; Zhang Yong-Gang; Song Yu-Xin; Ye Hong; Cao Yuan-Ying; Li Ai-Zhen; Wang Shu-Min

    2013-01-01

    The effect of bismuth on the optical properties of InGaAsBi/GaAs quantum well structures is investigated using the temperature-dependent photoluminescence from 12 K to 450 K.The incorporation of bismuth in the InGaAsBi quantum well is confirmed and found to result in a red shift of photoluminescence wavelength of 27.3 meV at 300 K.The photoluminescence intensity is significantly enhanced by about 50 times at 12 K with respect to that of the InGaAs quantum well due to the surfactant effect of bismuth.The temperature-dependent integrated photoluminescence intensities of the two samples reveal different behaviors related to various non-radiative recombination processes.The incorporation of bismuth also induces alloy non-uniformity in the quantum well,leading to an increased photoluminescence linewidth.

  15. Analysis of subsurface damage in silicon by a combined photothermal and photoluminescence heterodyne measurement

    Science.gov (United States)

    Geiler, H. D.; Karge, H.; Wagner, M.; Ehlert, A.; Kerstan, M.; Helmreich, D.

    1997-06-01

    A nondestructive evaluation technique based on the detection of the real part of the excess charge carrier wave by photoluminescence in a frequency range from 5 kHz up to 12 MHz is introduced for semiconductor defect analysis. Crystalline imperfections in silicon due to wafer manufacturing and processing are investigated and the results are correlated with those obtained from conventional photothermal measurements.

  16. 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.

  17. Photoluminescence topography of fluorescent SiC and its corresponding source crystals

    DEFF Research Database (Denmark)

    Wilhelm, M.; Kaiser, M.; Jokubavicus, V.

    2013-01-01

    The preparation and application of co-doped polycrystalline SiC as source in sublimation growth of fluorescent layers is a complex topic. Photoluminescence topographies of luminescent 6H-SiC layers and their corresponding source crystals have been studied in order to investigate the dependence...

  18. Enhancement of two-photon photoluminescence and SERS for low-coverage gold films

    DEFF Research Database (Denmark)

    Novikov, Sergey M.; Beermann, Jonas; Frydendahl, Christian

    2016-01-01

    Electromagnetic field enhancement (FE) effects occurring in thin gold films 3-12-nm are investigated with two-photon photoluminescence (TPL) and Raman scanning optical microscopies. The samples are characterized using scanning electron microscopy images and linear optical spectroscopy. TPL images...

  19. Pressure-induced quenching of the photoluminescence in sexithiophene single crystals observed by femtosecond spectroscopy

    NARCIS (Netherlands)

    Loi, M. A.; Mura, A; Bongiovanni, G; Cai, Q; Martin, C; Chandrasekhar, HR; Chandrasekhar, M; Graupner, W; Garnier, F

    2001-01-01

    The influence of interchain interactions on the photoluminescence processes in a sexithiophene single crystal is studied by applying hydrostatic pressure up to 60 kbar, Steady state and femtosecond-time resolved optical spectroscopies indicate that an ultrafast (100 fs) formation of intermolecular

  20. Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2012-03-01

    Full Text Available -1 ACS Appl. Mater. Interfaces 2012, 4, 1656-1665 dx.doi.org/10.1021/am2018089 Photoluminescence and Hydrogen Gas-Sensing Properties of Titanium Dioxide Nanostructures Synthesized by Hydrothermal Treatments Lucky M. Sikhwivhilu, Siyasanga Mpelane...

  1. 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

  2. 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...

  3. 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

    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...

  4. High pressure effects on the photoluminescence intensity of sexithiophene single crystals

    NARCIS (Netherlands)

    Loi, M.A.; Bongiovanni, G.; Mura, A.; Cai, Q.; Martin, C.; Chandrasekhar, H.R.; Chandrasekhar, M.; Graupner, W.; Garnier, F.

    2001-01-01

    We report on the influence of interchain interactions on the light emission properties of a sexithiophene single crystal. The strength of the intermolecular interactions is controlled by applying hydrostatic pressure. The combined use of both steady-state and time-resolved photoluminescence

  5. Phase-sensitive electric modulation of photoluminescence upon bichromatic excitation of atoms

    NARCIS (Netherlands)

    Astapenko, VA

    2005-01-01

    A new type of modulation of the photoluminescence intensity of atoms excited by a bichromatic laser radiation with the frequency ratio 1 : 2 is proposed and analysed. The modulation is produced by alternating electric field acting on atoms and occurs due to the quantum interference of the amplitudes

  6. 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...

  7. 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.

  8. Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species.

    Science.gov (United States)

    Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

    2017-02-10

    In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters.

  9. 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

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

    Science.gov (United States)

    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.

    2016-05-01

    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.

  11. 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.

  12. Bias-induced photoluminescence quenching of single colloidal quantum dots embedded in organic semiconductors.

    Science.gov (United States)

    Huang, Hao; Dorn, August; Nair, Gautham P; Bulović, Vladimir; Bawendi, Moungi G

    2007-12-01

    We demonstrate reversible quenching of the photoluminescence from single CdSe/ZnS colloidal quantum dots embedded in thin films of the molecular organic semiconductor N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) in a layered device structure. Our analysis, based on current and charge carrier density, points toward field ionization as the dominant photoluminescence quenching mechanism. Blinking traces from individual quantum dots reveal that the photoluminescence amplitude decreases continuously as a function of increasing forward bias even at the single quantum dot level. In addition, we show that quantum dot photoluminescence is quenched by aluminum tris(8-hydroxyquinoline) (Alq3) in chloroform solutions as well as in thin solid films of Alq3 whereas TPD has little effect. This highlights the importance of chemical compatibility between semiconductor nanocrystals and surrounding organic semiconductors. Our study helps elucidate elementary interactions between quantum dots and organic semiconductors, knowledge needed for designing efficient quantum dot organic optoelectronic devices.

  13. Synthesis and time-resolved photoluminescence of SnO2 nanorods

    Science.gov (United States)

    Sial, Muhammad Aurang Zeb Gul; Iqbal, Muzaffar; Siddique, Zumaira; Nadeem, Muhammad Arif; Ishaq, Muhammad; Iqbal, Azhar

    2017-09-01

    A solvo-thermal method is employed to synthesize SnO2 nanorods and the Fourier transformed infrared spectroscopic analysis confirms the formation of Snsbnd O bond. The X-ray diffraction analysis suggests that SnO2 nanorods exist in tetragonal rutile crystal structure phase. Transmission electron microscopy images show the formation of nanorods with an average diameter ∼10-15 nm and length 35-50 nm. The deconvoluted photoluminescence spectrum suggests the existence of three distinct origins of photoluminescence, which peaks at photon energies of ∼423 nm (2.93 eV), ∼470 nm (2.64 eV) and 480 nm (2.58 eV). The measured photoluminescence kinetics is best described by a tri-exponential decay model suggesting that the photoluminescence occurs from three distinct channels with time constants 1.31 ns, 4.89 ns and 13.24 ns. These studies suggest that SnO2 nanorods synthesized by solvo-thermal method at mild conditions can be used for luminescent device applications. The long lived emission of SnO2 nanorods in the visible region make them suitable candidate as an active materials for many opto-electronic devices such as light emitting diodes and solar cells.

  14. The Use of Photo-Luminescence as an Emergency Egress Guidance System on ISS

    Science.gov (United States)

    Maida, James C.

    2014-01-01

    Because ever increasing performance, photoluminescence has moved from “glow in the dark” toys to greatly expanded use in offices, factories, homes and many other places where it can be charged regularly by light and seen clearly and effectively in the dark for extended periods of time.

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

    Science.gov (United States)

    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

    2016-05-06

    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.

  16. Plasmonic pumping of excitonic photoluminescence in hybrid MoS2-Au nanostructures.

    Science.gov (United States)

    Najmaei, Sina; Mlayah, Adnen; Arbouet, Arnaud; Girard, Christian; Léotin, Jean; Lou, Jun

    2014-12-23

    We report on the fabrication of monolayer MoS2-coated gold nanoantennas combining chemical vapor deposition, e-beam lithography surface patterning, and a soft lift-off/transfer technique. The optical properties of these hybrid plasmonic-excitonic nanostructures are investigated using spatially resolved photoluminescence spectroscopy. Off- and in-resonance plasmonic pumping of the MoS2 excitonic luminescence showed distinct behaviors. For plasmonically mediated pumping, we found a significant enhancement (∼65%) of the photoluminescence intensity, clear evidence that the optical properties of the MoS2 monolayer are strongly influenced by the nanoantenna surface plasmons. In addition, a systematic photoluminescence broadening and red-shift in nanoantenna locations is observed which is interpreted in terms of plasmonic enhanced optical absorption and subsequent heating of the MoS2 monolayers. Using a temperature calibration procedure based on photoluminescence spectral characteristics, we were able to estimate the local temperature changes. We found that the plasmonically induced MoS2 temperature increase is nearly four times larger than in the MoS2 reference temperatures. This study shines light on the plasmonic-excitonic interaction in these hybrid metal/semiconductor nanostructures and provides a unique approach for the engineering of optoelectronic devices based on the light-to-current conversion.

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

    Science.gov (United States)

    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. PMID:27150276

  18. Enzyme biosensor systems based on porous silicon photoluminescence for detection of glucose, urea and heavy metals.

    Science.gov (United States)

    Syshchyk, Olga; Skryshevsky, Valeriy A; Soldatkin, Oleksandr O; Soldatkin, Alexey P

    2015-04-15

    A phenomenon of changes in photoluminescence of porous silicon at variations in medium pH is proposed to be used as a basis for the biosensor system development. The method of conversion of a biochemical signal into an optical one is applied for direct determination of glucose and urea as well as for inhibitory analysis of heavy metal ions. Changes in the quantum yield of porous silicon photoluminescence occur at varying pH of the tested solution due to the enzyme-substrate reaction. When creating the biosensor systems, the enzymes urease and glucose oxidase (GOD) were used as a bioselective material; their optimal concentrations were experimentally determined. It was shown that the photoluminescence intensity of porous silicon increased by 1.7 times when increasing glucose concentration in the GOD-containing reaction medium from 0 to 3.0mM, and decreased by 1.45 times at the same increase in the urea concentration in the urease-containing reaction medium. The calibration curves of dependence of the biosensor system responses on the substrate concentrations are presented. It is shown that the presence of heavy metal ions (Cu(2+), Pb(2+), and Cd(2+)) in the tested solution causes an inhibition of the enzymatic reactions catalyzed by glucose oxidase and urease, which results in a restoration of the photoluminescence quantum yield of porous silicon. It is proposed to use this effect for the inhibitory analysis of heavy metal ions. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Observation of Mode Splitting in Photoluminescence of Individual Plasmonic Nanoparticles Strongly Coupled to Molecular Excitons.

    Science.gov (United States)

    Wersäll, Martin; Cuadra, Jorge; Antosiewicz, Tomasz J; Balci, Sinan; Shegai, Timur

    2017-01-11

    Plasmon-exciton interactions are important for many prominent spectroscopic applications such as surface-enhanced Raman scattering, plasmon-mediated fluorescence, nanoscale lasing, and strong coupling. The case of strong coupling is analogous to quantum optical effects studied in solid state and atomic systems previously. In plasmonics, similar observations have been almost exclusively made in elastic scattering experiments; however, the interpretation of these experiments is often cumbersome. Here, we demonstrate mode splitting not only in scattering, but also in photoluminescence of individual hybrid nanosystems, which manifests a direct proof of strong coupling in plasmon-exciton nanoparticles. We achieved these results due to saturation of the mode volume with molecular J-aggregates, which resulted in splitting up to 400 meV, that is, ∼20% of the resonance energy. We analyzed the correlation between scattering and photoluminescence and found that splitting in photoluminescence is considerably less than that in scattering. Moreover, we found that splitting in both photoluminescence and scattering signals increased upon cooling to cryogenic temperatures. These findings improve our understanding of strong coupling phenomena in plasmonics.

  20. Near-Infrared Photoluminescence Properties of Endohedral Mono- and Dithulium Metallofullerenes.

    Science.gov (United States)

    Wang, Zhiyong; Izumi, Noriko; Nakanishi, Yusuke; Koyama, Takeshi; Sugai, Toshiki; Tange, Masayoshi; Okazaki, Toshiya; Shinohara, Hisanori

    2016-04-26

    The optical properties of endohedral metallofullerene molecules can be tuned by changing the fullerene size as well as the number of metal atoms inside the fullerene cages. In this work we have synthesized and isolated a series of mono- and dithulium metallofullerenes, including Tm@C82 (isomers I, II, III, IV), Tm@C88 (I-IV), Tm2@C82 (I-III), and (Tm2C2)@C82 (I-III). Near-infrared photoluminescence is observed from the thulium metallofullerenes. By changing the number of Tm ion in the fullerene cage, we have found that one can vary and tune the photoluminescence from 1200 to 1300-2000 nm observed for Tm(2+) (4f(13)) in Tm@C88 and Tm(3+) (4f(12)) in (Tm2C2)@C82, respectively. The photoluminescence intensity depends sensitively on the fullerene cages. (Tm2C2)@C82 (III) exhibits the highest photoluminescence intensity among the three structural isomers because of its large HOMO-LUMO energy gap.

  1. Characterization of Titania Incorporated with Alumina Nanocrystals and Their Impacts on Electrical Hysteresis and Photoluminescence

    Directory of Open Access Journals (Sweden)

    Shi Lei

    2009-01-01

    Full Text Available Abstract The structural and optical characterizations of titania incorporated with alumina nanocrystals have been presented in this paper and the films exhibit excellent properties like low current density, small hysteresis as well as high photoluminescence quantum yields of about 361 nm. These properties are promising for the applications in future electronic devices.

  2. Low-temperature photoluminescence analysis of CdTeSe crystals for radiation-detector applications

    Energy Technology Data Exchange (ETDEWEB)

    YANG G.; Roy, U. N.; Bolotnikov, A. E.; Cui, Y.; Camarda, G.S.; Hossain, A.; and James, R. B.

    2015-10-05

    Goal: Understanding the changes of material defects in CdTeSe following annealing. Experimental results and discussions: Infrared (IR) transmission microscopy; current-voltage measurements (Highlight: Improvement of resistivity of un-doped crystals after annealing); low-temperature photoluminescence (PL) spectrum of as-grown and annealed samples.

  3. Hydrothermal synthesis of two photoluminescent nitrogen-doped graphene quantum dots emitted green and khaki luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaohua; Zuo, Xiaoxi; Hu, Ruiping; Xiao, Xin; Liang, Yong; Nan, Junmin, E-mail: jmnan@scnu.edu.cn

    2014-10-15

    A simple and effective chemical synthesis of the photoluminescent nitrogen-doped graphene quantum dots (N-GQDs) biomaterial is reported. Using the hydrothermal treatment of graphene oxide (GO) in the presence of hydrogen peroxide (H{sub 2}O{sub 2}) and ammonia, the N-GQDs are synthesized through H{sub 2}O{sub 2} exfoliating the GO into nanocrystals with lateral dimensions and ammonia passivating the generated active surface. Then, after a dialytic separation, two water-soluble N-GQDs with average size of about 2.1 nm/6.2 nm, which emit green/khaki luminescence and exhibit excitation dependent/independent photoluminescence (PL) behaviors, are obtained. In addition, it is also demonstrated that these two N-GQDs are stable over a broad pH range and have the upconversion PL property, showing this approach provides a simple and effective method to synthesize the functional N-GQDs. - Highlights: • Nitrogen-doped graphene quantum dots (N-GQDs) are prepared by hydrothermal routine. • Two N-GQDs with different size distribution emit green/khaki photoluminescence. • Two N-GQDs exhibit excitation-dependent/independent photoluminescence behaviors.

  4. Anomalous temperature dependent photoluminescence properties of CdSxSe1-x quantum dots

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    CdSxSe1-x quantum dots were fabricated by a simple spin-coating heat volatilization method on InP wafer.Temperature dependent photoluminescence of CdSxSe1-x quantum dots was carried out in a range of 10-300 K.The integrated photoluminescence intensity revealed an anomalous behavior with increasing temperature in the range of 180-200 K.The band gap energy showed a redshift of 61.34 meV when the temperature increased from 10 to 300 K.The component ratio of S to Se in the CdSxSe1-x quantum dots was valued by both the X-ray diffraction data and photoluminescence peak energy at room temperature according to Vegard Law.Moreover,the parameters of the Varshni relation for CdS0.9Se0.1 materials were also obtained using photoluminescence peak energy as a function of temperature and the best-fit curve:α=(3.5 ± 0.1)10-4 eV/K,and β=210 ± 10 K (close to the Debye temperature θD of the material).

  5. Dependence of the two-photon photoluminescence yield of gold nanostructures on the laser pulse duration

    DEFF Research Database (Denmark)

    Biagioni, P.; Celebrano, M.; Savoini, M.

    2009-01-01

    Two-photon photoluminescence (TPPL) from gold nanostructures is becoming one of the most relevant tools for plasmon-assisted biological imaging and photothermal therapy as well as for the investigation of plasmonic devices. Here we study the yield of TPPL as a function of the temporal width δ of ...

  6. Phase-sensitive electric modulation of photoluminescence upon bichromatic excitation of atoms

    NARCIS (Netherlands)

    Astapenko, VA

    2005-01-01

    A new type of modulation of the photoluminescence intensity of atoms excited by a bichromatic laser radiation with the frequency ratio 1 : 2 is proposed and analysed. The modulation is produced by alternating electric field acting on atoms and occurs due to the quantum interference of the amplitudes

  7. Factors Influencing Photoluminescence and Photocarrier Lifetime in CdSeTe/CdMgTe Double Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, C. H.; Zaunbrecher, Katherine N.; Sohal, S.; LeBlanc, E. G.; Edirisooriya, M.; Ogedengbe, O. S.; Petersen, J. E.; Jayathilaka, P. A. R. D.; Myers, T. H.; Holtz, M. W.; Barnes, Teresa M.

    2016-10-28

    CdSeTe/CdMgTe double heterostructures were produced with both n-type and unintentionally doped absorber layers. Measurements of the dependence of photoluminescence intensity on excitation intensity were carried out, as well as measurements of time-resolved photoluminescence decay after an excitation pulse. It was found that decay times under very low photon injection conditions are dominated by a non-radiative Shockley-Read-Hall process described using a recombination center with an asymmetric capture cross section, where the cross section for holes is larger than that for electrons. As a result of the asymmetry, the center effectively extends photoluminescence decay by a hole trapping phenomenon. A reduction in electron capture cross section appeared at doping densities over 10^16cm-3. An analysis of the excitation intensity dependence of room temperature photoluminescence revealed a strong relationship with doping concentration. This allows estimates of the carrier concentration to be made through a non-destructive optical method. Iodine was found to be an effective n-type dopant for CdTe, allowing controllable carrier concentrations without an increased rate of non-radiative recombination.

  8. Kinetics of pulse-induced photoluminescence from a semiconductor quantum dot.

    Science.gov (United States)

    Rukhlenko, Ivan D; Leonov, Mikhail Yu; Turkov, Vadim K; Litvin, Aleksandr P; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V

    2012-12-03

    Optical methods, which allow the determination of the dominant channels of energy and phase relaxation, are the most universal techniques for the investigation of semiconductor quantum dots. In this paper, we employ the kinetic Pauli equation to develop the first generalized model of the pulse-induced photoluminescence from the lowest-energy eigenstates of a semiconductor quantum dot. Without specifying the shape of the excitation pulse and by assuming that the energy and phase relaxation in the quantum dot may be characterized by a set of phenomenological rates, we derive an expression for the observable photoluminescence cross section, valid for an arbitrary number of the quantum dot's states decaying with the emission of secondary photons. Our treatment allows for thermal transitions occurring with both decrease and increase in energy between all the relevant eigenstates at room or higher temperature. We show that in the general case of N states coupled to each other through a bath, the photoluminescence kinetics from any of them is determined by the sum of N exponential functions, whose exponents are proportional to the respective decay rates. We illustrate the application of the developed model by considering the processes of resonant luminescence and thermalized luminescence from the quantum dot with two radiating eigenstates, and by assuming that the secondary emission is excited with either a Gaussian or exponential pulse. Analytic expressions describing the signals of secondary emission are analyzed, in order to elucidate experimental situations in which the relaxation constants may be reliably extracted from the photoluminescence spectra.

  9. Polarized photoluminescence of nc-Si–SiO{sub x} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Michailovska, E. V.; Indutnyi, I. Z.; Shepeliavyi, P. E.; Sopinskii, N. V., E-mail: sopinsky@isp.kiev.ua, E-mail: sopinskyy@ua.fm [National Academy of Sciences of Ukraine, Lashkarev Institute of Semiconductor Physics (Ukraine)

    2016-01-15

    The effect of photoluminescence polarization memory in nc-Si–SiO{sub x} light-emitting structures containing Si nanoparticles (nc-Si) in an oxide matrix is for the first time studied. The polarization properties of continuous and porous nanostructures passivated in HF vapors (or solutions) are studied. It is established that the polarization memory effect is manifested only after treatment of the structures in HF. The effect is also accompanied by a shift of the photoluminescence peak to shorter wavelengths and by a substantial increase in the photoluminescence intensity. It is found that, in anisotropic nc-Si–SiO{sub x} samples produced by oblique deposition in vacuum, the degree of linear photoluminescence polarization in the sample plane exhibits a noticeable orientation dependence and correlates with the orientation of SiO{sub x} nanocolumns forming the structure of the porous layer. These effects are attributed to the transformation of symmetrically shaped Si nanoparticles into asymmetric elongated nc-Si particles upon etching in HF. In continuous layers, nc-Si particles are oriented randomly, whereas in porous structures, their preferential orientation coincides with the orientation of oxide nanocolumns.

  10. Structural Order-Disorder Transformations Monitored by X-Ray Diffraction and Photoluminescence

    Science.gov (United States)

    Lima, R. C.; Paris, E. C.; Leite, E. R.; Espinosa, J. W. M.; Souza, A. G.; Longo, E.

    2007-01-01

    A study was conducted to examine the structural order-disorder transformation promoted by controlled heat treatment using X-ray diffraction technique (XRD) and photoluminescence (PL) techniques as tools to monitor the degree of structural order. The experiment was observed to be versatile and easily achieved with low cost which allowed producing…

  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, ...

  12. Structural Order-Disorder Transformations Monitored by X-Ray Diffraction and Photoluminescence

    Science.gov (United States)

    Lima, R. C.; Paris, E. C.; Leite, E. R.; Espinosa, J. W. M.; Souza, A. G.; Longo, E.

    2007-01-01

    A study was conducted to examine the structural order-disorder transformation promoted by controlled heat treatment using X-ray diffraction technique (XRD) and photoluminescence (PL) techniques as tools to monitor the degree of structural order. The experiment was observed to be versatile and easily achieved with low cost which allowed producing…

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

    Science.gov (United States)

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

    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.

  14. 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.

  15. Synthesis and Photoluminescence of a New Red Phosphorescent Iridium(III) Quinoxaline Complex

    Institute of Scientific and Technical Information of China (English)

    Guo Lin ZHANG; Ze Hua LIU; Hai Qing GUO

    2004-01-01

    A new cyclometalated iridium(III) complex with the formula [Ir(DPQ)2(acac)] (DPQ= 2,3-diphenylquinoxaline; acac=acetylacetone) was prepared. The structure of the complex was confirmed by Elemental Analysis (EA), 1H NMR, and mass spectroscopy (MS). The UV-vis absorption and photoluminescent properties of the complex were investigated.

  16. Photoluminescence and Raman spectroscopy characterization of boron- and nitrogen-doped 6H silicon carbide

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Liu, Chuan

    2011-01-01

    Boron - and nitrogen-doped 6H silicon carbide epilayers grown on low off-axis 6H silicon carbide substrates have been characterized by photoluminescence and Raman spectroscopy. Combined with secondary ion mass spectrometry results, preferable doping type and optimized concentration could...

  17. Controlled suppression of the photoluminescence superlinear dependence on excitation density in quantum dots.

    Science.gov (United States)

    Bietti, Sergio; Sanguinetti, Stefano

    2012-10-04

    : We have shown that it is possible to tune, up to complete suppression, the photoluminescence superlinear dependence on the excitation density in quantum dot samples at high temperatures by annealing treatments. The effect has been attributed to the reduction of the defectivity of the material induced by annealing.

  18. 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.

  19. Coupled confinement effect on the photoluminescence and electrical transport in porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ciurea, M.L. E-mail: ciurea@alpha1.infim.ro; Draghici, M.; Iancu, V.; Reshotko, M.; Balberg, I

    2003-05-01

    In this paper we report correlations between the structure, the photoluminescence and the transport properties of luminescent porous silicon. These correlations combined with the observed temperature dependence of tunneling characteristics yield quite a wholesome (pea-pod-like) model for this system.

  20. Homogeneous linewidth of single InGaAs quantum dot photoluminescence

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Langbein, Wolfgang; Jensen, Jacob Riis

    2000-01-01

    We have used m-photoluminescence spectroscopy with a spectral resolution of 20 meV to measure homogeneous linewidths of single emission lines within an inhomogeneously broadened ensemble of In0.5Ga0.5As/GaAs self-assembled quantum dots. At 10K, a distribution of linewidths peaking around 50 me...

  1. Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species

    Science.gov (United States)

    Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

    2017-01-01

    In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)-capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters. PMID:28208642

  2. Magneto-photoluminescence spectroscopy of single InAs/AlAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, D; Meulen, H P van der; Calleja, J M [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Meyer, J M; Haug, R J [Institut fuer Festkoerperphysik, Leibniz Universitaet Hannover, D-30167 Hannover (Germany); Pierz, K, E-mail: D.Sarkar@sheffield.ac.u [Physikalisch-Technische Bundesanstalt Braunschweig, D-38116 Braunschweig (Germany)

    2010-02-01

    We present non-resonant, polarization-resolved magneto-photoluminescence measurements up to 12 T on single InAs/AlAs quantum dots. We observe typical g-factors between 1 and 2, very low diamagnetic shifts due to strong exciton localization and low-energy sidebands, which are attributed to the piezoelectric exciton-acoustic phonon interaction.

  3. Ascertaining free histidine from mixtures with histidine-containing proteins using time-resolved photoluminescence spectroscopy.

    Science.gov (United States)

    Huang, Kewei; Jiang, Chengmin; Martí, Angel A

    2014-11-13

    The use of photoluminescent probes for differentiating free amino acids from biomolecules containing the same amino acids is challenging. Photoluminescent probes generally present similar emission spectra when in the presence of either free-amino acids or protein containing those same amino acids. Probes based on cyclometalated iridium(III) complexes Ir(L)2(sol)2 (where L is 2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine, or benzo[h]quinolone, and sol is a solvent molecule) present long-lived emission when bound to histidine. This emission is tuned by the microenvironment around the complex and therefore its lifetime is different for free histidine (487 ns) than from histidine-containing proteins such as bovine serum albumin (average lifetime > 700 ns). As a proof-of-concept we demonstrate that free histidine can be discerned from a mixture with histidine-containing proteins by using time-resolved photoluminescence decays. In the presence of multiple sources of histidine, iridium(III) probes display a multiexponential decay, which can be fitted by nonlinear least-squares methods to separate the different components. Because the pre-exponential factor of the 487 ns lifetime is proportional to the concentration of free histidine, we can use it to assess the amount of free histidine in solution even in the presence of proteins such as bovine serum albumin. We also show that iridium(III) probes displaying different photoluminescence maxima can be produced by modifying the ancillary ligands of the metal complex.

  4. High-resolution dynamic pressure sensor array based on piezo-phototronic effect tuned photoluminescence imaging.

    Science.gov (United States)

    Peng, Mingzeng; Li, Zhou; Liu, Caihong; Zheng, Qiang; Shi, Xieqing; Song, Ming; Zhang, Yang; Du, Shiyu; Zhai, Junyi; Wang, Zhong Lin

    2015-03-24

    A high-resolution dynamic tactile/pressure display is indispensable to the comprehensive perception of force/mechanical stimulations such as electronic skin, biomechanical imaging/analysis, or personalized signatures. Here, we present a dynamic pressure sensor array based on pressure/strain tuned photoluminescence imaging without the need for electricity. Each sensor is a nanopillar that consists of InGaN/GaN multiple quantum wells. Its photoluminescence intensity can be modulated dramatically and linearly by small strain (0-0.15%) owing to the piezo-phototronic effect. The sensor array has a high pixel density of 6350 dpi and exceptional small standard deviation of photoluminescence. High-quality tactile/pressure sensing distribution can be real-time recorded by parallel photoluminescence imaging without any cross-talk. The sensor array can be inexpensively fabricated over large areas by semiconductor product lines. The proposed dynamic all-optical pressure imaging with excellent resolution, high sensitivity, good uniformity, and ultrafast response time offers a suitable way for smart sensing, micro/nano-opto-electromechanical systems.

  5. Reduction of Photoluminescence Quenching by Deuteration of Ytterbium-Doped Amorphous Carbon-Based Photonic Materials

    Directory of Open Access Journals (Sweden)

    Hui-Lin Hsu

    2014-08-01

    Full Text Available In situ Yb-doped amorphous carbon thin films were grown on Si substrates at low temperatures (<200 °C by a simple one-step RF-PEMOCVD system as a potential photonic material for direct integration with Si CMOS back end-of-line processing. Room temperature photoluminescence around 1 µm was observed via direct incorporation of optically active Yb3+ ions from the selected Yb(fod3 metal-organic compound. The partially fluorinated Yb(fod3 compound assists the suppression of photoluminescence quenching by substitution of C–H with C–F bonds. A four-fold enhancement of Yb photoluminescence was demonstrated via deuteration of the a-C host. The substrate temperature greatly influences the relative deposition rate of the plasma dissociated metal-organic species, and hence the concentration of the various elements. Yb and F incorporation are promoted at lower substrate temperatures, and suppressed at higher substrate temperatures. O concentration is slightly elevated at higher substrate temperatures. Photoluminescence was limited by the concentration of Yb within the film, the concentration of Yb ions in the +3 state, and the relative amount of quenching due to the various de-excitation pathways associated with the vibrational modes of the host a-C network. The observed wide full-width-at-half-maximum photoluminescence signal is a result of the variety of local bonding environments due to the a-C matrix, and the bonding of the Yb3+ ions to O and/or F ions as observed in the X-ray photoelectron spectroscopy analyses.

  6. Quantifying Alumina Nanoparticle Dispersion in Hybrid Carbon Fiber Composites Using Photoluminescent Spectroscopy.

    Science.gov (United States)

    Hanhan, Imad; Selimov, Alex; Carolan, Declan; Taylor, Ambrose C; Raghavan, Seetha

    2017-02-01

    Composites modified with nanoparticles are of interest to many researchers due to the large surface-area-to-volume ratio of nano-scale fillers. One challenge with nanoscale materials that has received significant attention is the dispersion of nanoparticles in a matrix material. A random distribution of particles often ensures good material properties, especially as it relates to the thermal and mechanical performance of composites. Typical methods to quantify particle dispersion in a matrix material include optical, scanning electron, and transmission electron microscopy. These utilize images and a variety of analysis methods to describe particle dispersion. This work describes how photoluminescent spectroscopy can serve as an additional technique capable of quickly and comprehensively quantifying particle dispersion of photoluminescent particles in a hybrid composite. High resolution 2D photoluminescent maps were conducted on the front and back surfaces of a hybrid carbon fiber reinforced polymer containing varying contents of alumina nanoparticles. The photoluminescent maps were analyzed for the intensity of the alumina R1 fluorescence peak, and therefore yielded alumina particle dispersion based on changes in intensity from the embedded nanoparticles. A method for quantifying particle sedimentation is also proposed that compares the photoluminescent data of the front and back surfaces of each hybrid composite and assigns a single numerical value to the degree of sedimentation in each specimen. The methods described in this work have the potential to aid in the manufacturing processes of hybrid composites by providing on-site quality control options, capable of quickly and noninvasively providing feedback on nanoparticle dispersion and sedimentation.

  7. Manipulation and Quantification of Graphene Oxide Flake Size: Photoluminescence and Cytotoxicity.

    Science.gov (United States)

    Coleman, Brian R; Knight, Timothy; Gies, Valerie; Jakubek, Zygmunt J; Zou, Shan

    2017-08-30

    Single-layered graphene oxide (GO) has exhibited great promise in the areas of sensing, membrane filtration, supercapacitors, bioimaging, and therapeutic carriers because of its biocompatibility, large surface area, and electrochemical, photoluminescent, and optical properties. To elucidate how the physical dimensions of GO affect its intrinsic properties, we employed sonication to produce more than 130 different sizes of GO in aqueous dispersion and implemented new approaches to characterize various GO properties as a function of the average flake size. New protocols were developed to determine and compare the flake size of GO dispersions sonicated with energies up to 20 MJ/g by using dynamic light scattering and atomic force microscopy (AFM). The relationship between the average flake size and sonication energy per unit mass of GO was observed to follow a power law. AFM height measurements showed that the sonication of GO yielded monolayered flakes. Photoluminescence of GO was characterized as a function of the sonication energy (or the average flake size which is the monotonic function of the sonication energy), excitation wavelength, and pH of the dispersion. The strong dependence of the photoluminescence intensity on pH control and the variation of the photoluminescence intensity with different flake sizes were observed. An intense photoluminescence signal, likely related to the separation of the oxidative debris from the GO framework, was found at the highest sonication energies (E ≳ 15 MJ/g) or under extremely alkaline conditions (pH ≳ 11). The cytotoxicity of GO was studied with various flake sizes. Size- and concentration-dependent cytotoxicity was observed for cell lines NIH 3T3 and A549. The NIH 3T3 cell line also demonstrated time-dependent cytotoxicity.

  8. Near-infrared photoluminescence of orange color standards - then and now

    Science.gov (United States)

    Zwinkels, Joanne C.; Noël, Mario; Hillman, Sean

    2013-08-01

    The presence of near-infrared (NIR) photoluminescence has been recently reported in some of the second series of Ceramic Color Standards (CCSII) that are widely used in the calibration and performance evaluation of color measuring instruments. The impact of this photoluminescence effect can cause significant colorimetric errors particularly for broadband measurements using a detector with high spectral responsivity in the NIR region. The magnitude of this effect has been demonstrated for specific color standards and specific instrument systems but has not been unambiguously quantified to allow general predictions or absolute comparisons of different instrument designs or different ceramic tiles. Here we present absolute NIR photoluminescence measurements on three different formulations of the CCSII orange ceramic color standard using the National Research Council of Canada (NRC) Reference Spectrofluorimeter whose spectral range has been recently extended to 1000 nm. The validation for this extended spectral range is shown by comparison of an independent method of instrument calibration using a different combination of physical standards. It is convincingly shown that the two different leaded formulations of this ceramic orange standard issued in 2000 and 2011 have no significant photoluminescence and thus can be used for calibration with any type of spectrophotometer design whereas the unleaded formulation issued in 2011 has significant NIR photoluminescence and should not be used for instrument calibration and validation over an extended range into the NIR for certain spectrophotometers with relatively high throughput in the NIR region, such as a spectrophotometer with polychromatic illumination mode using a xenon source or with monochromatic illumination mode using a Si detector. It is shown that for colorimetric applications, the impact of this NIR fluorescence is only significant for the latter spectrophotometer design with broadband detection with a Si or

  9. Photoluminescence Enhancement in Nanotextured Fluorescent SiC Passivated by Atomic Layer Deposited Al2O3 Films

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    The influence of thickness of atomic layer deposited Al2O3 films on nano-textured fluorescent 6H-SiC passivation is investigated. The passivation effect on the light emission has been characterized by photoluminescence and time-resolved photoluminescence at room temperature. The results show...... that 20nm thickness of Al2O3 layer is favorable to observe a large photoluminescence enhancement (25.9%) and long carrier lifetime (0.86ms). This is a strong indication for an interface hydrogenation that takes place during post-thermal annealing. These results show that an Al2O3 layer could serve...

  10. Highly efficient photoluminescence of SiO2 and Ce-SiO2 microfibres and microspheres.

    Science.gov (United States)

    Ruso, Juan M; Gravina, A Noel; D'Elía, Noelia L; Messina, Paula V

    2013-06-14

    Semiconductor nanocrystals and nanostructures have been extensively studied in the last few years due to their interesting optical and optoelectronic properties. Nevertheless, combining precise photoluminescence properties with controlled morphologies of SiO2 is a major hurdle for a broad range of basic research and technological applications. Here, we demonstrate that microemulsion droplet interfacial elasticity can be manipulated to induce definite morphologies associated with specific intrinsic and extrinsic photoluminescent defects in the silica matrix. Thus, under precise experimental conditions hollow crystalline and compact amorphous SiO2 spheres showing ultraviolet-photoluminescence and helicoidal fibrils of Ce-doped amorphous silica with violet-blue emissions are obtained. Overall, it is demonstrated that the combination of microemulsions and doping represents an easy strategy for the design of specific nanoscale structures with high efficiency photoluminescence. The detailed structural analysis provided in the present work is expected to be useful as accurate information on assessment of technological nanostructures.

  11. Thermal effects on structure and photoluminescence properties of diamond-like carbon films prepared by pulsed laser deposition

    Institute of Scientific and Technical Information of China (English)

    CHEN Da; LI Qing-shan; WANG Jing-jing; ZHENG Xue-gang

    2006-01-01

    Un-hydrogenated Diamond-like Carbon (DLC) films were prepared by pulsed laser deposition technique at different substrate temperature.The Raman spectra,the absorption and the photoluminescence spectra were measured.The dependence of structure and photoluminescence properties on deposition temperature were studied in detail.The experimental results indicate that the sp2 sites form small clusters that consist of both olefinic chains and aromatic ring groups within the sp3 matrix.With raising deposition temperature,the optical band gaps increase from 1.87 to 2.85 eV.The main band of photoluminescence centered at around 700nm shifts to short wavelength,and the intensity of this band increases.The photoluminescence can be attributed to carrier localization within an increasing sp2 clusters.It was clarified that the DLC films are ordered with increasing deposition temperature.

  12. Diffusion length and resistivity distribution characteristics of silicon wafer by photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Dohyun; Lee, Jaehyeong; Choi, Byoungdeog, E-mail: bdchoi@skku.edu

    2014-10-15

    Highlights: • Analytical photoluminescence efficiency calculation and PL intensity ratio method are developed. • Wafer resistivity and diffusion length characteristics are investigated by PL intensity ratio. • PL intensity is well correlated with resistivity, diffusion length or defect density on wafer measurement. - Abstract: Photoluminescence is a convenient, contactless method to characterize semiconductors. Its use for room-temperature silicon characterization has only recently been implemented. We have developed the PL efficiency theory as a function of substrate doping densities, bulk trap density, photon flux density, and reflectance and compared it with experimental data initially for bulk Si wafers. New developed PL intensity ratio method is able to predict the silicon wafer properties, such as doping densities, minority carrier diffusion length and bulk trap density.

  13. Preparation and photoluminescence properties of Sm3+-doped ZrO2 nanotube arrays

    Science.gov (United States)

    Fu, Ning; Wang, Xixin; Ma, Yuanhui; Wang, Mingli; Li, Jiaxin; Zhao, Jianling

    2016-04-01

    Zr-Sm (3 at.% Sm) alloy was prepared through a powder metallurgical method. Sm3+-doped ZrO2 nanotube arrays have been achieved directly by anodizing the Zr-Sm alloy. The effects of electrolyte and annealing temperature on the morphologies and structures of the nanotube arrays were studied. The photoluminescence properties of Sm3+-doped ZrO2 nanotube arrays prepared in aqueous solution and formamide  +  glycerol solution were studied in detail as well. Results show that tetragonal ZrO2 promoted the photoluminescence efficiency of this system. Under excitation at 407 nm, the sample prepared in aqueous solution annealed at 600 °C displayed the strongest emission peak at 571 nm, corresponding to the 4G5/2  →  6H5/2 samarium transition.

  14. Time-resolved ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer

    Directory of Open Access Journals (Sweden)

    Qing Yang

    2014-02-01

    Full Text Available The ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer grown by the thermal oxidation of ZnS with gallium was investigated by the time-resolved photoluminescence as a function of measuring temperature and excitation power. With increase of excitation power, the D0X emission is easily saturated than the DAP emission from ZnO/ZnGa2O4 composite layer, and which is dramatically enhanced as compared with that from pure ZnO layer grown without gallium. The radiative recombination process with ultra-long lifetime controlled the carrier recombination of ZnO/ZnGa2O4 composite layer.

  15. Photoluminescence enhancement in few-layer WS2 films via Au nanoparticles

    Directory of Open Access Journals (Sweden)

    Sin Yuk Choi

    2015-06-01

    Full Text Available Nano-composites of two-dimensional atomic layered WS2 and Au nanoparticles (AuNPs have been fabricated by sulfurization of sputtered W films followed by immersing into HAuCl4 aqueous solution. The morphology, structure and AuNPs distribution have been characterized by electron microscopy. The decorated AuNPs can be more densely formed on the edge and defective sites of triangle WS2. We have compared the optical absorption and photoluminescence of bare WS2 and Au-decorated WS2 layers. Enhancement in the photoluminescence is observed in the Au-WS2 nano-composites, attributed to localized surface plasmonic effect. This work provides the possibility to develop photonic application in two-dimensional materials.

  16. Formation of silicon nanocrystals in sapphire by ion implantation and the origin of visible photoluminescence

    Science.gov (United States)

    Yerci, S.; Serincan, U.; Dogan, I.; Tokay, S.; Genisel, M.; Aydinli, A.; Turan, R.

    2006-10-01

    Silicon nanocrystals, average sizes ranging between 3 and 7nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800°C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. While the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix.

  17. Photoluminescence in silicon implanted with erbium ions at an elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Kalyadin, A. E.; Shek, E. I.; Sakharov, V. I.; Serenkov, I. T. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Vdovin, V. I. [St. Petersburg University, Fock Research Institute of Physics (Russian Federation); Parshin, E. O.; Makoviichuk, M. I. [Russian Academy of Sciences, Yaroslavl Branch, Institute of Physics and Technology (Russian Federation)

    2011-08-15

    Photoluminescence spectra of n-type silicon upon implantation with erbium ions at 600 Degree-Sign C and oxygen ions at room temperature and subsequent annealings at 1100 Degree-Sign C in a chlorine-containing atmosphere have been studied. Depending on the annealing duration, photoluminescence spectra at 80 K are dominated by lines of the Er{sup 3+} ion or dislocation-related luminescence. The short-wavelength shift of the dislocation-related luminescence line observed at this temperature is due to implantation of erbium ions at an elevated temperature. At room temperature, lines of erbium and dislocation-related luminescence are observed in the spectra, but lines of near-band-edge luminescence predominate.

  18. Electrochemically grafted polypyrrole changes photoluminescence of electronic states inside nanocrystalline diamond

    Energy Technology Data Exchange (ETDEWEB)

    Galář, P., E-mail: pavel.galar@mff.cuni.cz; Malý, P. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, Prague 121 16 (Czech Republic); Čermák, J.; Kromka, A.; Rezek, B. [Institute of Physics ASCR v.v.i., Cukrovarnická 10, Prague 160 00 (Czech Republic)

    2014-12-14

    Hybrid diamond-organic interfaces are considered attractive for diverse applications ranging from electronics and energy conversion to medicine. Here we use time-resolved and time-integrated photoluminescence spectroscopy in visible spectral range (380–700 nm) to study electronic processes in H-terminated nanocrystalline diamond films (NCD) with 150 nm thin, electrochemically deposited polypyrrole (PPy) layer. We observe changes in dynamics of NCD photoluminescence as well as in its time-integrated spectra after polymer deposition. The effect is reversible. We propose a model where the PPy layer on the NCD surface promotes spatial separation of photo-generated charge carriers both in non-diamond carbon phase and in bulk diamond. By comparing different NCD thicknesses we show that the effect goes as much as 200 nm deep inside the NCD film.

  19. Coherence properties of the photoluminescence from CdS-ZnO nanocomposite thin films.

    Science.gov (United States)

    Vasa, Parinda; Singh, B P; Ayyub, Pushan

    2005-01-12

    The application of semiconductor quantum dots in important new areas such as random lasing and quantum-information processing requires knowledge of the coherence of the optical emission from such systems. We report the first direct experimental estimation of the coherence in the light emitted by a nanoparticle ensemble. The photoluminescence from a two-phase nanocomposite CdS-ZnO thin film (with a characteristic grain size of 2-3 nm for both the chemical phases) possesses an appreciable degree of spatial and temporal coherence at room temperature. The degree of spatial coherence was estimated from the classical Young's double slit experiment. We also discuss a simple technique for estimating the degree of spectral coherence of the photoluminescence from thin films.

  20. Temperature Dependence of Photoluminescence from Single and Ensemble InAs/GaAs Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    DOU Xiu-Ming; SUN Bao-Quan; XIONG Yong-Hua; HUANG She-Song; NI Hai-Qiao; NIU Zhi-Chuan

    2008-01-01

    We investigate the temperature dependence of photoluminescence from single and ensemble InAs/GaAs quantum dots systematically. As temperature increases, the exciton emission peak for single quantum dot shows broadening and redshift. For ensemble quantum dots, however, the exciton emission peak shows narrowing and fast redshift.We use a simple steady-state rate equation model to simulate the experimental data of photoluminescence spectra.It is confirmed that carrier-phonon scattering gives the broadening of the exciton emission peak in single quantum dots while the effects of carrier thermal escape and retrapping play an important role in the narrowing and fast redshift of the exciton emission peak in ensemble quantum dots.

  1. Time-Resolved Photoluminescence Studies of Indium-Rich InGaN Alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Guang-De; ZHU You-Zhang; YAN Guo-Jun; YUAN Jin-She; K.H.Kim; J.Y.Lin; H.X.Jiang

    2005-01-01

    @@ Time-resolved photoluminescence (PL) spectroscopy has be used to investigate indium-rich InGaN alloys grown on sapphire substrates by metal organic chemical vapor deposition. Photoluminescence measurement indicates two dominant emission lines originating from phase-separated high- and low-indium-content regions. Temperature and excitation intensity dependence of the two main emission lines in these InGaN alloys have been measured.Temperature and energy dependence of PL decay lifetime show clearly different decay behaviour for the two main lines. Our results show that photo-excited carriers are deeply localized in the high indium regions while photo-excited carriers can be transferred within the low-indium-content regions as well as to high-content regions.

  2. AgCl-doped CdSe quantum dots with near-IR photoluminescence.

    Science.gov (United States)

    Kotin, Pavel Aleksandrovich; Bubenov, Sergey Sergeevich; Mordvinova, Natalia Evgenievna; Dorofeev, Sergey Gennadievich

    2017-01-01

    We report the synthesis of colloidal CdSe quantum dots doped with a novel Ag precursor: AgCl. The addition of AgCl causes dramatic changes in the morphology of synthesized nanocrystals from spherical nanoparticles to tetrapods and finally to large ellipsoidal nanoparticles. Ellipsoidal nanoparticles possess an intensive near-IR photoluminescence ranging up to 0.9 eV (ca. 1400 nm). In this article, we explain the reasons for the formation of the ellipsoidal nanoparticles as well as the peculiarities of the process. The structure, Ag content, and optical properties of quantum dots are also investigated. The optimal conditions for maximizing both the reaction yield and IR photoluminescence quantum yield are found.

  3. Understanding the Photoluminescence Mechanism of Nitrogen-Doped Carbon Dots by Selective Interaction with Copper Ions.

    Science.gov (United States)

    Ganiga, Manjunatha; Cyriac, Jobin

    2016-08-04

    Doped fluorescent carbon dots (CDs) have drawn widespread attention because of their diverse applications and attractive properties. The present report focusses on the origin of photoluminescence in nitrogen-doped CDs (NCDs), which is unraveled by the interaction with Cu(2+) ions. Detailed spectroscopic and microscopic studies reveal that the broad steady-state photoluminescence emission of the NCDs originates from the direct recombination of excitons (high energy) and the involvement of defect states (low energy). In addition, highly selective detection of Cu(2+) is achieved, with a detection limit of 10 μm and a dynamic range of 10 μm-0.4 mm. The feasibility of the present sensor for the detection of Cu(2+) in real water samples is also presented. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Investigation of diffusion length distribution on polycrystalline silicon wafers via photoluminescence methods

    Science.gov (United States)

    Lou, Shishu; Zhu, Huishi; Hu, Shaoxu; Zhao, Chunhua; Han, Peide

    2015-01-01

    Characterization of the diffusion length of solar cells in space has been widely studied using various methods, but few studies have focused on a fast, simple way to obtain the quantified diffusion length distribution on a silicon wafer. In this work, we present two different facile methods of doing this by fitting photoluminescence images taken in two different wavelength ranges or from different sides. These methods, which are based on measuring the ratio of two photoluminescence images, yield absolute values of the diffusion length and are less sensitive to the inhomogeneity of the incident laser beam. A theoretical simulation and experimental demonstration of this method are presented. The diffusion length distributions on a polycrystalline silicon wafer obtained by the two methods show good agreement. PMID:26364565

  5. Strong infrared photoluminescence in highly porous layers of large faceted Si crystalline nanoparticles

    Science.gov (United States)

    de Jong, E. M. L. D; Mannino, G.; Alberti, A.; Ruggeri, R.; Italia, M.; Zontone, F.; Chushkin, Y.; Pennisi, A. R.; Gregorkiewicz, T.; Faraci, G.

    2016-01-01

    Almost all physical processes in solids are influenced by phonons, but their effect is frequently overlooked. In this paper, we investigate the photoluminescence of large silicon nanoparticles (approximately 100 nm size, synthesized by chemical vapor deposition) in the visible to the infrared detection range. We find that upon increasing laser irradiance, an enormous photoluminescence emission band appears in the infrared. Its intensity exhibits a superlinear power dependence, increasing over four orders of magnitude in the investigated pump power range. Particles of different sizes as well as different shapes in porous layers are investigated. The results are discussed taking into account the efficient generation of phonons under high-power pumping, and the reduced capability, porosity dependent, of the silicon nanoparticles to exchange energy with each other and with the substrate. Our findings are relevant for heat management strategies in silicon. PMID:27216452

  6. Photoluminescence and thermoluminescence studies of CaAl2O4:Dy(3+) phosphor.

    Science.gov (United States)

    Ziyauddin, Mohammad; Tigga, Shalinta; Brahme, Nameeta; Bisen, D P

    2016-02-01

    Calcium aluminate phosphors activated by Dy(3+) have been prepared by a combustion method at a temperature of 600°C. Photoluminescence (PL) and thermoluminescence (TL) properties of gamma-irradiated Dy-doped calcium aluminate were investigated. The PL spectrum shows a broad peak around 488 nm and 573 nm, under 347 nm excitation. Thermoluminescence studies were performed for different concentrations of Dy. Optimum intensity of photoluminescence was found for 0.02 mol% concentration of Dy. It was found that initially the peak TL intensity increases with increasing concentration of Dy in the CaAl2O4 host, attains a maximum value for 0.05 mol% concentration and decreases with further increase in the doping concentration due to concentration quenching. Copyright © 2015 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

    Al-Jumaili, Batool E. B.; Talib, Zainal A.; Josephine L., Y.; Paiman, Suriati B.; Ahmed, Naser M.; Al-Jumaily, Abdulmajeed H. J.; Ramizy, Asmiet; Abdulateef, Sinan A.; Muh'd, Ibrahim B.; Mofdal, Manahil E. E.

    2016-07-01

    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 65mA/cm2.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.

  8. 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.

  9. Photoluminescence changes of III-Nitride lateral polarity structures after chemical functionalization

    Science.gov (United States)

    Berg, Nora G.; Franke, Alexander; Kirste, Ronny; Collazo, Ramon; Ivanisevic, Albena

    2016-12-01

    The photoluminescence changes of a III-Nitride semiconductor with various surface topographies were studied after chemical functionalization. Al x Ga1-x N with a composition of 70% aluminum was used and the surfaces were functionalized with a fluorophore dye-terminated peptide using a linker molecule. The stability of the wafers in water was studied using inductively coupled plasma mass spectrometry prior to modifying the material. The leaching data demonstrated that the AlGaN material in highly stable in biological conditions over 7 d. The attachment of the dye to the wafer was investigated using x-ray photoelectron spectroscopy and photoluminescence spectroscopy (PL). The PL spectrum showed a clear signature of the dye with a pronounced emission peak at approximately 260 nm, indicating a successful attachment to the surface.

  10. Structural and photoluminescent properties of ZnO films deposited by radio frequency reactive sputtering

    Institute of Scientific and Technical Information of China (English)

    PENG XingPing; WANG ZhiGuang; SONG Yin; JI Tao; ZANG Hang; YANG YingHu; JIN YunFan

    2007-01-01

    Zinc oxide films with c-axis preferred orientation were deposited on silicon (100)substrates by radio frequency (RF) reactive sputtering. The properties of the samples were characterized by X-ray diffractometer, X-ray photoelectron spectroscopy and fluorescent-spectrophotometer. The effect of sputtering power and substrate temperature on the structural and photoluminescent (PL) properties of the ZnO films was investigated. The results indicated that when the sputtering power is 100 W and the substrate temperature is 300-400℃, it is suitable for the growth of high c-axis orientation and small strain ZnO films. A violet peak at about 380 nm and a blue band at about 430 nm were observed in the room temperature photoluminescence spectra, and the origin of blue emission was investigated.

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

    Science.gov (United States)

    Lin, Chung-Yi; Huang, Chih-Hsiung; Huang, Shih-Hsien; Chang, Chih-Chiang; Liu, C. W.; Huang, Yi-Chiau; Chung, Hua; Chang, Chorng-Ping

    2016-08-01

    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 Al2O3/SiO2 passivation due to the field effect. The electroluminescence of the direct bandgap emission of strained GeSn is also observed from the Ni/Al2O3/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 Al2O3 and recombine radiatively with electrons. The emission wavelength of photoluminescence and electroluminescence can be tuned by the Sn content.

  12. Photophysical properties and biocompatibility of Photoluminescent Y2O3:Eu nanoparticles in polymethylmetacrylate matrix.

    Science.gov (United States)

    Abe, Shigeaki; Hamba, Yusuke; Iwadera, Nobuki; Yamagata, Shuichi; Yawaka, Yasutaka; Uo, Motohiro; Iida, Junichiro; Kiba, Takayuki; Murayama, Akihiro; Watari, Fumio

    2014-04-01

    In this study, we produced europium-doped yttoria (Y2O3:Eu) nanoparticles and investigated their photoluminescent properties and biocompatibility. The Y2O3:Eu nanoparticles showed excellent photoluminescent properties and cytocompatibility. We also analyzed the photophysical properties of the nanoparticles in PMMA films. When the Y2O3:Eu nanoparticles were incorporated in the polymer film, they showed a strong red emission spectrum, similar to that seen with the particles alone. Energy dispersive X-ray spectroscopy (EDS) measurements indicated that the particles were distributed homogeneously in the PMMA film. Such materials could be applied not only to optoelectronic devices but also to biomedical applications such as bioimaging tools or luminescent medical/dental adhesive materials.

  13. Geometry modulated upconversion photoluminescence of individual NaYF4: Yb3+, Er3+ microcrystals

    Science.gov (United States)

    Wang, Bing; Wang, Jiao; Mei, Yongfeng

    2017-02-01

    Upconversion (UC) photoluminescence (PL) properties of individual β-NaYF4: Yb3+, Er3+ microcrystals are investigated on their crystal orientation and size by a confocal micro-photoluminescence (μ-PL) system. The UC PL intensities including red and green bands of individual microcrystals change nearly lineally with their diameter but in different slopes. The ratio of integrated PL intensities between red and green bands (R/G) of individual microcrystals can be modulated by the crystal geometry, which is attributed to the optical propagation path and optical loss coefficient α. PL emission mapping along the crystal surface reveals a typical characteristic of optical waveguide in our UC microcrystals. Importantly, the variation of anisotropy in (100) and (001) crystal plane influences the UC PL spectra in the single microcrystals. Our finding could help the basic understanding of UC luminescence in micro/nanocrystals and hint their optimized fabrication for enhanced light emission.

  14. Controlled growth of ZnO nanorods by polymer template and their photoluminescence properties

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A large amount of one-dimensional ZnO nanorods with diameters in 15―50 nm aligned in radial cluster were successfully synthesized by polar polymer polyvinyl alcohol (PVA) as soft-template. The growth of ZnO nanorods was controlled by changing annealing temperature. The evolution of the morphology and microstructure was investigated by scanning electron microscope, transmission electron micro- scope and X-ray diffraction. It is shown that ZnO nanorods tend to be uniform and the crystallization is gradually improved with the temperature increasing from 400℃ to 700℃. The photoluminescence spectra of products show a strong ultra violet emission and relatively weak defect emissions. The sharp strong emission peak at 354 nm owing to the inter-band transition indicates the extraordinary photoluminescence property of ZnO nanorods.

  15. Investigation on the structural and photoluminescent properties of chromium-doped ceramics cordierite

    Science.gov (United States)

    da Silva, M. A. F. M.; Pedro, S. S.; López, A.; Sosman, L. P.

    2016-10-01

    This work presents the investigation about the structural and optical properties of a doped-chromium system containing cordierite (Mg2Al4Si5O18) as main phase. The sample composition and the structural data were obtained from X-ray diffraction (XRD) measurements and the results were analyzed by Rietveld method. Photoluminescence (PL) spectra under several excitation wavelengths and photoluminescence excitation (PLE) measurements were performed. The obtained results from PL and PLE experiments are evidences that Cr3+ occupies octahedral sites in this ceramic system. By correlating the optical results, the crystal field parameter (Dq) and Racah interelectronic repulsion parameters (B and C) were calculated and discussed according to the Tanabe-Sugano (TS) theory for d3 transition metals in octahedral sites.

  16. Temperature dependent photoluminescence characteristics of nanocrystalline ZnO films grown by sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, S.; Goswami, M.L.N.; Das, K.; Dhar, A. [Department of Physics and Meteorology, IIT Kharagpur 721 302 (India); Ray, S.K. [Department of Physics and Meteorology, IIT Kharagpur 721 302 (India)], E-mail: physkr@phy.iitkgp.ernet.in

    2008-10-01

    The structural as well as optical properties of nanocrystalline ZnO films, with hexagonal shaped particles of size 30-35 nm grown on p-Si (100) substrates by sol-gel technique, are investigated. Selected-area electron diffraction and X-ray diffraction patterns of annealed films reveal the formation of wurtzite structure. The mechanism of ultraviolet (UV) and green emission from ZnO thin films, post-annealed at various temperatures, is investigated using photoluminescence spectra. The oxygen content in annealed ZnO films plays an important role to suppress the green band emission. Temperature dependent photoluminescence spectra are recorded in the temperature range 10 K to 300 K to investigate different excitonic peaks in the UV-region.

  17. Synthesis and Photoluminescence of Three Europium (Ⅲ) Ternary Complexes with New Secondary Ligands of Different Structure

    Institute of Scientific and Technical Information of China (English)

    袁继兵; 李嘉航; 梁万里; 苏树江; 石建新; 龚孟濂

    2004-01-01

    Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium (Ⅲ) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium (Ⅲ) ternary complexes were confirmed by elementary analysis, IR and 1H-NMR spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(Ⅲ) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(Ⅲ) complexes are good red-emitiing materials for potential application in fabrication of organic electroluminescence devices.

  18. 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.

  19. Accurate radiation temperature and chemical potential from quantitative photoluminescence analysis of hot carrier populations

    Science.gov (United States)

    Gibelli, François; Lombez, Laurent; Guillemoles, Jean-François

    2017-02-01

    In order to characterize hot carrier populations in semiconductors, photoluminescence measurement is a convenient tool, enabling us to probe the carrier thermodynamical properties in a contactless way. However, the analysis of the photoluminescence spectra is based on some assumptions which will be discussed in this work. We especially emphasize the importance of the variation of the material absorptivity that should be considered to access accurate thermodynamical properties of the carriers, especially by varying the excitation power. The proposed method enables us to obtain more accurate results of thermodynamical properties by taking into account a rigorous physical description and finds direct application in investigating hot carrier solar cells, which are an adequate concept for achieving high conversion efficiencies with a relatively simple device architecture.

  20. 'School adopts an experiment': the photoluminescence in extra-virgin olive oil and in tonic water

    Science.gov (United States)

    Agliolo Gallitto, A.; Agnello, S.; Cannas, M.

    2011-09-01

    We report a laboratory activity, carried out along with high- and secondary-school students, that can be done to increase the interest of the young in scientific studies. Groups of selected students 'adopted' experiments at physics research laboratories, under the guidance of university researchers. Subsequently, the students demonstrated the experiments to the public at large during the annual science festival organized in Palermo by the association PalermoScienza, in collaboration with the University of Palermo. Experiments on the magnetic levitation of superconductors and on the photoluminescence of several substances were proposed. We discuss the experiment on photoluminescence as a case study. The students who adopted the experiments reinforced their commitment to learning. They acquired a physics-based knowledge of the topics connected with the experiments in a much better way compared with the usual didactics in school.

  1. Probing the exciton density of states in semiconductor nanocrystals using integrated photoluminescence spectroscopy

    CERN Document Server

    Filonovich, S A; Vasilevskiy, M I; Rolo, A G; Gomes, M J M; Artemiev, M V; Talapin, D V; Rogach, A L

    2002-01-01

    We present the results of a comparative analysis of the absorption and photoluminescence excitation (PLE) spectra vs. integrated photoluminescence (IPL) measured as a function of the excitation wavelength for a number of samples containing II-VI semiconductor nanocrystals (NCs) produced by different techniques. The structure of the absorption and PL spectra due to excitons confined in NCs and difficulties with the correct interpretation of the transmittance and PLE results are discussed. It is shown that, compared to the conventional PLE, the IPL intensity plotted against the excitation wavelength (IPLE spectra) reproduce better the structure of the absorption spectra. Therefore, IPLE spectroscopy can be successfully used for probing the quantized electron-hole (e-h) transitions in semiconductor nanocrystals. (author)

  2. Theoretical and Experimental Study of Time- and Temperature-Dependent Photoluminescence in ZnO

    Science.gov (United States)

    Shishehchi, Sara; Garrett, Gregory A.; Rudin, Sergey; Wraback, Michael; Bellotti, Enrico

    2014-08-01

    In this work, we investigate the dynamics of photo-excited carriers in ZnO. Specifically, we study the luminescence spectrum and the effect of temperature on the luminescence rise time. For comparison, experimental time- resolved photo-luminescence studies on ZnO samples are performed. In the theoretical model, interaction with a laser pulse is treated coherently and a generalized Monte Carlo simulation is used to account for scattering processes. The scattering mechanisms included are carrier interactions with polar optical phonons and acoustic phonons, and carrier-carrier Coulomb interactions. We observed a good agreement between the experimental and simulation results for the photo-luminescence spectrum. Furthermore, as the temperature increases, the luminescence rise time decreases, mostly due to the weaker effect of polar optical scattering at lower temperature.

  3. Origin of photoluminescence from silicon nanowires prepared by metal induced etching (MIE)

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Shailendra K., E-mail: shailendra.saxena3@gmail.com; Rai, Hari. M.; Late, Ravikiran [Material Research Laboratory, Discipline of Physics, School of Basic Sciences, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India); Sagdeo, Pankaj R.; Kumar, Rajesh [Material Research Laboratory, Discipline of Physics, School of Basic Sciences, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India); Material Science and Engineering Group, Indian Institute of Technology Indore, Madhya Pradesh-452017 (India)

    2015-05-15

    In this present study the origin of luminescence from silicon nanowires (SiNws) has been studied. SiNWs are fabricated on Si substrate by metal induced chemical etching (MIE). Here it is found that the band gap of SiNWs is higher than the gap of luminescent states in SiNWs which leads to the effect of Si=O bond. The band gap is estimated from diffuse reflectance analysis. Here we observe that band gap can be tailored depending on size (quantum confinement) but photoluminescence (PL) from all the sample is found to be fixed at 1.91 eV. This study is important for the understanding of origin of photoluminescence.

  4. 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.

  5. Synthesis and Photoluminescence Studies on Catalytically Grown Zn1 – xMnxS Nanowires

    Directory of Open Access Journals (Sweden)

    R. Venugopal

    2011-01-01

    Full Text Available Zn1 – xMnxS alloy nanowires with composition (x = 0.0, 0.1 and 0.3 have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 2 nm thickness. X-ray powder diffraction measurements reveal that as synthesized products were hexagonal wurtzite structure. The as grown nanowires have been investigated by Scanning Electron Microscopy (SEM, Transmission Electron Microscopy (TEM, Energy Dispersive Analysis of X-rays (EDAX and photoluminescence studies. The results reveal that the as grown nanowires consist of Zn, Mn, and S material and diameter ranging from 70 - 150 nm with lengths up to several tens of micrometers. Photoluminescence studies on Zn1 – xMnxS exhibited peaks at 600 and 613 nm for x = 0.1 and 0.3 respectively.

  6. Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jayachandraiah, C. [Department of Physics, JNTU, Anantapur-515002 (India); Kumar, K. Siva [Department of Advanced Materials Science and Engineering, Dankook University, Cheonan, Chungnam 330-714 (Korea, Republic of); Krishnaiah, G., E-mail: ginnerik@gmail.com [Govt. Degree College, Puttur, Chittoor-517 583 (India)

    2015-06-24

    Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PL studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.

  7. Photoluminescence Mechanism of DNA-Templated Silver Nanoclusters: Coupling between Surface Plasmon and Emitter and Sensing of Lysozyme.

    Science.gov (United States)

    Liu, Xiaorong; Hu, Ruoxin; Gao, Zhidan; Shao, Na

    2015-06-02

    DNA-templated silver nanoclusters (DNA-AgNCs) have now been thrust into the limelight with their superior optical properties and potential biological applications. However, the origin of photoluminescence from DNA-AgNCs still remains unclear. In this work, DNA-AgNCs were synthesized and the photoluminescence properties as well as the biosensing applications of the designed DNA-AgNCs were investigated. The photoluminescence properties of the DNA-AgNCs were studied under three regions of excitation wavelength based on the UV-visible absorption spectra. It was deemed that the photoluminescence originated from coupling between the surface plasmon and the emitter in AgNCs when they were excited by visible light above 500 nm, and thus the emission wavelength varied with changing the excitation wavelength. The photoluminescence of the red-emitting-only AgNCs was the intrinsic fluorescence when excited from 200 to 400 nm, which was only related to the emitter; but for two components of blue- and red-emitting AgNCs, the emission wavelength varied with the excitation wavelength ranging from 300 to 360 nm, and the photoluminescence was a coupling between the surface plasmon and the emitter. The photoluminescence was only related to the surface plasmon when the AgNCs were excited from 400 to 500 nm. Four DNA probes were designed and each contained two parts: one part was the template used to synthesize AgNCs and it was same to all, and the other part was the lysozyme binding DNA (LBD) used to bind lysozyme and two kinds of LBD were studied. It was deemed that the difference in DNA bases, sequence, and secondary structure caused the synthesized DNA-AgNCs to be different in photoluminescence properties and sensing ability to lysozyme, and the sensing mechanism based on photoluminescence enhancement was also presented. This work explored the origin of photoluminescence and the sensing ability of DNA-AgNCs, and is hoped to make a better understanding of this kind of

  8. Multifunctional porous silicon nanopillar arrays: antireflection, superhydrophobicity, photoluminescence, and surface-enhanced Raman scattering (SERS)

    OpenAIRE

    Kiraly, Brian; Yang, Shikuan; Huang, Tony Jun

    2013-01-01

    We have fabricated porous silicon nanopillar arrays over large areas with a rapid, simple, and low-cost technique. The porous silicon nanopillars show unique longitudinal features along their entire length and have porosity with dimensions on the single-nanometer scale. Both Raman spectroscopy and photoluminescence data were used to determine the nanocrystallite size to be < 3 nm. The porous silicon nanopillar arrays also maintained excellent ensemble properties, reducing reflection nearly fi...

  9. Study on Interaction Between Chitosan and CdS Quantum Dots via Photoluminescence Spectra

    Institute of Scientific and Technical Information of China (English)

    Zhan LI; Yu Min DU; Yan WEN

    2004-01-01

    The interaction between CdS quantum dots and amino polysaccharide chitosan in aqueous solution was studied via photoluminescence(PL)spectra. The surface binding of chitosan with different molecular weight(MW)quenched the luminescence of QDs due to the elimination of radioactive anion vacancy centers.This process fits well with the Perrin model;lower MW chitosan exhibits higher quenching efficiency due to better availability to the surface.

  10. 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...

  11. Photoluminescence enhancement of aligned arrays of single-walled carbon nanotubes by polymer transfer

    Science.gov (United States)

    Schweiger, Manuel; Zakharko, Yuriy; Gannott, Florentina; Grimm, Stefan B.; Zaumseil, Jana

    2015-10-01

    The photoluminescence of as-grown, aligned single-walled carbon nanotubes (SWNTs) on quartz is strongly quenched and barely detectable. Here we show that transferring these SWNTs to another substrate such as clean quartz or glass increases their emission efficiency by up to two orders of magnitude. By statistical analysis of large nanotube arrays we show at what point of the transfer process the emission enhancement occurs and how it depends on the receiving substrate and the employed transfer polymer. We find that hydrophobic polystyrene (PS) as the transfer polymer results in higher photoluminescence enhancement than the more hydrophilic poly(methyl methacrylate) (PMMA). Possible mechanisms for this enhancement such as strain relief, disruption of the strong interaction of SWNTs with the substrate and localized emissive states are discussed.The photoluminescence of as-grown, aligned single-walled carbon nanotubes (SWNTs) on quartz is strongly quenched and barely detectable. Here we show that transferring these SWNTs to another substrate such as clean quartz or glass increases their emission efficiency by up to two orders of magnitude. By statistical analysis of large nanotube arrays we show at what point of the transfer process the emission enhancement occurs and how it depends on the receiving substrate and the employed transfer polymer. We find that hydrophobic polystyrene (PS) as the transfer polymer results in higher photoluminescence enhancement than the more hydrophilic poly(methyl methacrylate) (PMMA). Possible mechanisms for this enhancement such as strain relief, disruption of the strong interaction of SWNTs with the substrate and localized emissive states are discussed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05163k

  12. 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.

  13. Structural and photoluminescence studies of TiO{sub 2} nanoparticles synthesized by solution combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, M., E-mail: chem.muruga@gmail.com; Silambarasan, M. [Centre for Photonics and Nanotechnology, Department of Science, Sona College of Technology, Salem – 636 005, Tamilnadu (India); Saravanan, S. [Centre for Photonics and Nanotechnology, Department of Science, Sona College of Technology, Salem – 636 005, Tamilnadu (India); Department of Frontier Materials, Nagoya Institute of Technology, Nagoya - 466-8555 (Japan); Soga, Tetsuo [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya - 466-8555 (Japan)

    2015-06-24

    In this study titanium dioxide nanoparticle is prepared by simple solution combustion method. The powder X-ray diffraction pattern indicates the prepared titanium dioxide nanoparticles crystalline nature with tetragonal structure. Also it shows the nanoparticle is anatase and rutile mixed phase. The Field Emission Scanning Electron Microscopy image shows the nanostructure of particles in the size range about 50 nm. Room temperature photoluminescence shows intrinsic defects of oxygen vacancies.

  14. Photoluminescence, time-resolved emission and photoresponse of plasma-modified porous silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Benyahia, Be., E-mail: benyahiabedra@hotmail.com [Unité de Développement de la Technologie du Silicium, 2 Boulevard Frantz Fanon, B.P. 140, Alger-7 Merveilles, Algiers 16200 (Algeria); Guerbous, L. [Centre de Recherche Nucléaire d' Alger, 2 Boulevard Frantz Fanon, B.P. 399, Alger-Gare, Algiers 16000 (Algeria); Gabouze, N.; Mahmoudi, Br. [Unité de Développement de la Technologie du Silicium, 2 Boulevard Frantz Fanon, B.P. 140, Alger-7 Merveilles, Algiers 16200 (Algeria)

    2013-07-01

    Photoluminescence and photoelectrical study on plasma-modified porous silicon (PS) thin films is presented. Porous silicon passivated by hydrocarbon groups (CH{sub x}) shows an intense broad and stable photoluminescence (PL) band centered at 623 nm whereas the maximum of the photosensitivity spectrum is placed around 400 nm. Along with its potential utilization for silicon-based light emitters' fabrication, it could also represent an appealing option for the improvement of energy conversion efficiency in silicon-based solar cells whether by using its luminescence properties (photon down-conversion) or the excess photocurrent produced by an improved high-energy photon's absorption. Excitation spectra (PLE) under steady-state conditions are reported. PLE shows that visible PL is excited by light from UV region. The time-resolved photoluminescence of CH{sub x}/PS in the range of some tenth of μs are investigated at room temperature. The PL decay line shape, in CH{sub x}/PS is well described by stretched exponential. The photosensitivity spectroscopy shows a significant increase of absorption at high photon energy excitation. - Highlights: • Coating porous silicon (PS) by hydrocarbon (CH{sub x}) reduces nonradiative transition. • Drop of the photoluminescence (PL) intensity. • The PL of CH{sub x}/PS is due to radiative transitions at 1.8 and 1.87 eV. • Photosensitivity revealed an excess spectral response (SR) at high-energy excitation. • For photovoltaic PL and SR could be used for the evolution of the silicon solar cells.

  15. The photoluminescence of ZnSe bulk single crystals excited by femtosecond pulse

    Institute of Scientific and Technical Information of China (English)

    Li Huan-Yong; Jie Wan-Qi; Zhang Shi-An; Sun Zhen-Rong; Xu Ke-Wei

    2006-01-01

    This paper reports on the photoluminescence spectra of ZnSe single crystal with trace chlorine excited by the femtosecond laser pulse. Three emission bands, including second-harmonic-generation, two-photon-excited peak and a broad band at 500-700nm, were detected. The thermal strain induced by femtosecond pulse strongly influences the photoluminescence of ZnSe crystal. The corresponding strain e in ZnSe crystal is estimated to be about 8.8 × 10-3 at room temperature. The zinc-vacancy, as the main point defect induced by femtosecond pulse, is successfully used to interpret the broad emission at 500-700nm. The research shows that self-activated luminescence possesses the recombination mechanism of donor-vacancy pair, and it is also influenced by a few selenium defects and the temperature.The rapid decrease in photoluminescence intensity of two-photon-excited fluorescence and second-harmonic generation emission at lower temperature is attributed to the fact that more point defects result in the thermal activation of the two-photo-absorption energy converting to the stronger recombination emission of chlorine-zinc vacancy in 500-700nm. The experimental results indicate that the femtosecond exciting photoluminescence shows a completely different emission mechanism to that of He-Cd exciting luminescence in ZnSe single crystal. The femtosecond laser exhibits a higher sensitive to the impurity in crystal materials, which can be recommended as an efficient way to estimate the trace impurity in high quality crystals.

  16. Photoluminescence and electro-optic properties of small (25-35 nm diameter) quantum boxes

    Science.gov (United States)

    Davis, L.; Ko, K. K.; Li, W.-Q.; Sun, H. C.; Lam, Y.; Brock, T.; Pang, S. W.; Bhattacharya, P. K.; Rooks, M. J.

    1993-05-01

    The luminescence and electro-optic properties of buried 25-35 nm quantum boxes have been measured. The quantum boxes were defined by a combination of molecular beam epitaxial growth and regrowth, electron beam lithography, and dry etching. The photoluminescence from 35 nm boxes shows a blue shift of about 15 meV compared to the bulk luminescence and an enhancement, taking into account the fill factor. An enhanced effective linear electrooptic coefficient is observed for the quantum boxes.

  17. Selected applications of photothermal and photoluminescence heterodyne techniques for process control in silicon wafer manufacturing

    Science.gov (United States)

    Ehlert, Andreas; Kerstan, Michael; Lundt, Holger; Huber, Anton; Helmreich, Dieter; Geiler, Hans-Dieter; Karge, Harald; Wagner, Matthias

    1997-02-01

    Two noncontact laser-based heterodyne techniques, photothermal heterodyne (PTH) and photoluminescence heterodyne (PLH), are introduced and applied to processing and quality control in silicon wafer manufacturing. The crystallographic characteristics of process-induced defects in silicon wafers are suitable for the application of PTH and PLH techniques, which are demonstrated on selected examples from different steps of silicon wafer production. Both PLH and PTH techniques meet the demand for nondestructive and on-line-suitable measurement in the semiconductor industry.

  18. Core-Shell Structure and Photoluminescence of CdS Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    邹炳锁; 武振羽; 曹立; 戴建华; 张泽勃; 聂玉昕; 解思深

    2001-01-01

    A double-potential-well model is proposed to describe the core-shell thickness-dependent photoluminescence peaks and energy relaxations in semiconductor quantum dots (QDs). The surface effect plays an important role in the formation of new states-polaronic states around the surface of QDs. The polaronic states formed emit light due to the strong interaction between the core state (confined state) and the surface state with an enhanced participation of the size effect.

  19. Investigation on the pH-independent photoluminescence emission from carbon dots impregnated on polymer matrix.

    Science.gov (United States)

    Saheeda, Pichan; Sabira, Kaviladath; Dhaneesha, Mohandas; Jayaleksmi, Sankaran

    2017-07-17

    Highly luminescent, polymer nanocomposite films based on poly(vinyl alcohol) (PVA), and monodispersed carbon dots (C-dots) derived from multiwalled carbon nanotubes (MWCNTs), as coatings on substrates as well as free standing ones are obtained via solution-based techniques. The synthesized films exhibit pH-independent photoluminescence (PL) emission, which is an advantageous property compared with the pH-dependent photoluminescence intensity variations, generally observed for the C-dots dispersed in aqueous solution. The synthesized C-dots and the nanocomposite films are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), ultraviolet (UV) - visible spectroscopy and photoluminescence spectroscopy (PL) techniques. The TEM image provides clear evidence for the formation of C-dots of almost uniform shape and average size of about 8 nm, homogeneously dispersed in aqueous medium. The strong anchoring of C-dots within the polymer matrix can be confirmed from the XRD results. The FTIR spectral studies conclusively establish the presence of oxygen functional groups on the surfaces of the C-dots. The photoluminescence (PL) emission spectra of the nanocomposite films are broad, covering most part of the visible region. The PL spectra do not show any luminescence intensity variations, when the pH of the medium is changed from 1 to 11. The pH-independent luminescence, shown by these films offers ample scope for using them as coatings for designing diagnostic and imaging tools in bio medical applications. The non-toxic nature of these nanocomposite films has been established on the basis of cytotoxicity studies. Copyright © 2017 John Wiley & Sons, Ltd.

  20. Cathodoluminescence and photoluminescence of swift ion irradiation modified zinc oxide-porous silicon nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Yogesh [CIICAp, UAEM, Av. Univ. 1001, Col. Chamilpa, Cuer., Mor., C.P. 62209 (Mexico); CIMAV, Av. Miguel de Cervantes 120, Compl. Indus. Chih., Chih., C.P. 31109 (Mexico); Herrera, Manuel [CNyN-UNAM, Ensenada Apdo. Postal 14, CP. 22800, Ensenada, B.C. (Mexico); Singh, Fouran [Inter University Accelarator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India); Olive-Mendez, S.F. [CIMAV, Av. Miguel de Cervantes 120, Compl. Indus. Chih., Chih., C.P. 31109 (Mexico); Kanjilal, D.; Kumar, Shiv [Inter University Accelarator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India); Agarwal, V., E-mail: vagarwal@uaem.mx [CIICAp, UAEM, Av. Univ. 1001, Col. Chamilpa, Cuer., Mor., C.P. 62209 (Mexico)

    2012-09-20

    We report the room temperature cathodoluminescence and photoluminescence of swift ion irradiated (130 MeV Nickel ion) porous silicon zinc oxide nanocomposites. The evolution of a broad and flat emission band from 1.5 to 3.5 eV is demonstrated. Annealing effect of irradiation is found to result in a relative increase in the band edge emission. Emission wavelength can be tuned in the complete visible range by changing the substrate characteristics.

  1. Influence of Parameters of a Printing Plate on Photoluminescence of Nanophotonic Printed Elements of Novel Packaging

    OpenAIRE

    Olha Sarapulova; Valentyn Sherstiuk

    2015-01-01

    In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and offset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of their photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out the formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polyprop...

  2. Photoluminescence Study of Low Thermal Budget III–V Nanostructures on Silicon by Droplet Epitaxy

    Directory of Open Access Journals (Sweden)

    Isella G

    2010-01-01

    Full Text Available Abstract We present of a detailed photoluminescence characterization of high efficiency GaAs/AlGaAs quantum nanostructures grown on silicon substrates. The whole process of formation of the GaAs/AlGaAs active layer was realized via droplet epitaxy and migration enhanced epitaxy maintaining the growth temperature ≤350°C, thus resulting in a low thermal budget procedure compatible with back-end integration of the fabricated materials on integrated circuits.

  3. Role of the crystallization substrate on the photoluminescence properties of organo-lead mixed halides perovskites

    OpenAIRE

    2014-01-01

    We have fabricated CH3NH3PbI3−xClx perovskite thin films crystallized in situ on substrates of different natures (e.g., porosity, wettability) and investigated their photoluminescence properties. We observe that the crystallization time and thin film structure are strongly influenced by the chemical nature and porosity of the substrate. Moreover, we find that the mesoporous scaffold can tune the emissive properties of the semiconducting compound both in terms of spectral region and dynamics. ...

  4. Photoluminescence Behaviour of Sm3+ Ions in presence of Ag Nanoparticles in Methanol

    Science.gov (United States)

    Dehingia, N.; Gogoi, P.; Boruah, A.; Kakoti, D.; Rajkonwar, N.; Dutta, P.

    2016-10-01

    In the present work, capped Ag NPs prepared by reduction of Ag (NO3)3 by Dimethyl Formamide is doped with Sm3+ in methanol and its photoluminescence behavior is studied. Significant modifications of the Sm3+ ions’ emission as well as quantum yield, were observed with the concentration of Ag NPs. Local field enhancement induced by neutral Ag NPs were found to be responsible for enhancement in efficiency of the Sm3+ ions.

  5. Effect of ZnS nanoparticles on the photoluminescence of Sm3+ ions in methanol

    Science.gov (United States)

    Kakoti, D.; Rajkonwar, N.; Dehingia, N.; Boruah, A.; Gogoi, P.; Dutta, P.

    2016-10-01

    ZnS nanoparticles co-doped with Sm3+ ions were prepared in methanol medium for fixed Sm3+ and varying ZnS concentrations. Enhancements in absorption as well as photoluminescence efficiency of the co-doped samples were observed. This enhanced efficiency is attributed to the effective increase in oscillator strengths of the Sm3+ transitions because of the addition of ZnS nanoparticles.

  6. Enhancing the Photoluminescence of Peptide-Coated Nanocrystals with Shell Composition and UV Irradiation

    OpenAIRE

    Tsay, James M.; Doose, Sören; Pinaud, Fabien; Weiss, Shimon

    2005-01-01

    The composition and structure of inorganic shells grown over CdSe semiconductor nanocrystal dots and rods were optimized to yield enhanced photoluminescence properties after ligand exchange followed by coating with phytochelatin-related peptides. We show that, in addition to the peptides imparting superior colloidal properties and providing biofunctionality in a single-step reaction, the improved shells and pretreatment with UV irradiation resulted in high quantum yields for the nanocrystals ...

  7. Nanostructured Metal-Enhanced Photoluminescence of Micro-Sr2Si5N8:Eu2+ Phosphors

    Institute of Scientific and Technical Information of China (English)

    LIU Ling; XU Xiao-Liang; LEI Jie-Mei; YIN Nai-Qiang

    2012-01-01

    The enhancement of the photoluminescence of micro-Sr2Si5N8:Eu2+ phosphors on the surface of kg and Au nanoparticles is studied. Ag nanoparticles cause a considerable enhancement in the photoluminescence intensity of microsized Sr2Si5N8:Eu2+ phosphors. We further investigate the enhanced emission of self-assembled worm-like Au nanoparticles from Sr2Si5N8:Eu2+ phosphors. A brightness photoluminescence intensity enhanced by about six times is observed, and is due to the stronger scattering and higher numbers of hot spots in the Au worms. The luminescence efficiency of the microparticles is higher than the nanoparticles, and it is very difficult to enhance light emission. Therefore, the realization of microphosphor photoluminescence enhancement is a great breakthrough.%The enhancement of the photoluminescence of micro-Sr2Si5N8:Eu2+ phosphors on the surface of Ag and Au nanoparticles is studied.Ag nanoparticles cause a considerable enhancement in the photoluminescence intensity of microsized Sr2Si5N8:Eu2+ phosphors.We further investigate the enhanced emission of self-assembled wormlike Au nanoparticles from Sr2Si5Ns:Eu2+ phosphors.A brightness photoluminescence intensity enhanced by about six times is observed,and is due to the stronger scattering and higher numbers of hot spots in the Au worms.The luminescence efficiency of the microparticles is higher than the nanoparticles,and it is very difficult to enhance light emission.Therefore,the realization of microphosphor photoluminescence enhancement is a great breakthrough.

  8. Experimental observation of spatially resolved photo-luminescence intensity distribution in dual mode upconverting nanorod bundles

    Science.gov (United States)

    Kumar, Pawan; Singh, Satbir; Singh, V. N.; Singh, Nidhi; Gupta, R. K.; Gupta, Bipin Kumar

    2017-02-01

    A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively. The TEM/HRTEM results confirm that these bundles are composed of several individual nanorods with diameter of ~100 nm and length in the range of 1–3 μm. Furthermore, two dimensional spatially resolved photoluminescence intensity distribution study has been carried out using confocal photoluminescence microscope throughout the nanorod bundles. This study provides a new direction for the potential use of such emerging dual mode nanorod bundles as photon sources for next generation flat panel optical display devices, bio-medical applications, luminescent security ink and enhanced energy harvesting in photovoltaic applications.

  9. Tuning photoluminescence properties of ZnO nanorods via surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin [National Center for Nanoscience and Technology, Beijing 100190 China (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xia, Yujing [National Center for Nanoscience and Technology, Beijing 100190 China (China); He, Tao, E-mail: het@nanoctr.cn [National Center for Nanoscience and Technology, Beijing 100190 China (China)

    2012-12-14

    Zinc oxide (ZnO) is a versatile material that has been used in photocatalysis, solar cells, chemical sensors, and piezoelectric transducers. All these are directly related to its surface properties. Here ZnO nanorod arrays were successfully synthesized by electrochemical deposition method, the surface of which was modified by dopamine, a robust anchor. Compared with pristine ZnO sample, the surface modification can greatly enhance the ultraviolet and visible-light photoluminescence. This is due to the formation of polydopamine on the nanorod surface, which may act as a dye that can be photoexcited. The resultant photogenerated electrons can inject into the conduction band of ZnO and take part in the luminescent process. These results may provide a foundation for real applications of ZnO nanomaterials in optoelectronic devices and, especially, for the applications in biological field as both the dopamine and ZnO are biocompatible materials. -- Highlights: Black-Right-Pointing-Pointer ZnO nanorod arrays are prepared via a simple electrochemical deposition method. Black-Right-Pointing-Pointer Photoluminescence of ZnO nanorods can be greatly enhanced via dopamine treatment. Black-Right-Pointing-Pointer Dye-like polydopamine can be formed on the nanorod surface upon dopamine treatment. Black-Right-Pointing-Pointer Photogenerated electrons in polydopamine can inject into conduction band of ZnO. Black-Right-Pointing-Pointer Enhanced photoluminescence is because more electrons can contribute to it.

  10. Photoconductivity, photoluminescence and optical Kerr nonlinear effects in zinc oxide films containing chromium nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Torres, C., E-mail: crstorres@yahoo.com.mx [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, Mexico, DF 07738 (Mexico); Garcia-Cruz, M.L. [Centro de Investigacion en Dispositivos Semiconductores, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Castaneda, L., E-mail: luisca@sirio.ifuap.buap.mx [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Rangel Rojo, R. [CICESE/Depto. de Optica, A. P. 360, Ensenada, BC 22860 (Mexico); Tamayo-Rivera, L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, DF 01000 (Mexico); Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN-SEES, A. P. 14740, Mexico DF 07000 (Mexico); Avendano-Alejo, M., E-mail: imax_aa@yahoo.com.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, A. P. 70-186, 04510, DF (Mexico); and others

    2012-04-15

    Chromium doped zinc oxide thin solid films were deposited on soda-lime glass substrates. The photoconductivity of the material and its influence on the optical behavior was evaluated. A non-alkoxide sol-gel synthesis approach was used for the preparation of the samples. An enhancement of the photoluminescence response exhibited by the resulting photoconductive films with embedded chromium nanoclusters is presented. The modification in the photoconduction induced by a 445 nm wavelength was measured and then associated with the participation of the optical absorptive response. In order to investigate the third order optical nonlinearities of the samples, a standard time-resolved Optical Kerr Gate configuration with 80 fs pulses at 830 nm was used and a quasi-instantaneous pure electronic nonlinearity without the contribution of nonlinear optical absorption was observed. We estimate that from the inclusion of Cr nanoclusters into the sample results a strong optical Kerr effect originated by quantum confinement. The large photoluminescence response and the important refractive nonlinearity of the photoconductive samples seem to promise potential applications for the development of multifunctional all-optical nanodevices. - Highlights: Black-Right-Pointing-Pointer Enhancement in photoluminescence for chromium doped zinc oxide films is presented. Black-Right-Pointing-Pointer A strong and ultrafast optical Kerr effect seems to result from quantum confinement. Black-Right-Pointing-Pointer Photoconductive properties for optical and optoelectronic functions were observed.

  11. Highly sensitive detection of ionizing radiations by a photoluminescent uranyl organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Jian; Wang, Yaxing; Liu, Wei; Yin, Xuemiao; Chen, Lanhua; Diwu, Juan; Chai, Zhifang; Wang, Shuao [School for Radiological and interdisciplinary Sciences (RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou (China); Zou, Youming [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui (China); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL (United States); Liu, Guokui [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL (United States)

    2017-06-19

    Precise detection of low-dose X- and γ-radiations remains a challenge and is particularly important for studying biological effects under low-dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X- or γ-radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10{sup -4} Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo-radicals that can be stabilized within the conjugated uranium oxalate-carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single-crystal structure of the γ-ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon-assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Hydrophobic perfluoro-silane functionalization of porous silicon photoluminescent films and particles

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, C.; Laplace, P.; Gallach-Pérez, D.; Pellacani, P.; Martín-Palma, R.J. [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Torres-Costa, V. [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, 28049, Madrid (Spain); Ceccone, G. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020, Ispra (Italy); Manso Silván, M., E-mail: miguel.manso@uam.es [Departamento de Física Aplicada e Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049, Madrid (Spain)

    2016-09-01

    Highlights: • Hydrophobic functionalization of porous silicon structures. • Perfluorooctyl group binding confirmed by XPS. • Improved stability face to extreme oxidation conditions. • Perfluorooctyl functionalization compatible with photoluminescence of porous silicon particles. - Abstract: Luminescent structures based on semiconductor quantum dots (QDs) are increasingly used in biomolecular assays, cell tracking systems, and in-vivo diagnostics devices. In this work we have carried out the functionalization of porous silicon (PSi) luminescent structures by a perfluorosilane (Perfluoro-octyltriethoxysilane, PFOS) self assembly. The PFOS surface binding (traced by X-ray photoelectron spectroscopy) and photoluminescence efficiency were analyzed on flat model PSi. Maximal photoluminescence intensity was obtained from PSi layers anodized at 110 mA/cm{sup 2}. Resistance to hydroxylation was assayed in H{sub 2}O{sub 2}:ethanol solutions and evidenced by water contact angle (WCA) measurements. PFOS-functionalized PSi presented systematically higher WCA than untreated PSi. The PFOS functionalization was found to slightly improve the aging of the PSi particles in water giving rise to particles with longer luminescent life. Confirmation of PFOS binding to PSi particles was derived from FTIR spectra and the preservation of luminescence was observed by fluorescence microscopy. Such functionalization opens the possibility of promoting hydrophobic-hydrophobic interactions between biomolecules and fluorescent QD structures, which may enlarge their biomedical applications catalogue.

  13. Origin of highly efficient photoluminescence in AgIn5S8 nanoparticles.

    Science.gov (United States)

    Han, Noh Soo; Yoon, Hee Chang; Jeong, Seonghyun; Oh, Ji Hye; Park, Seung Min; Do, Young Rag; Song, Jae Kyu

    2017-07-27

    The photoluminescence of AgIn5S8 nanoparticles was examined to clarify the emissive relaxation processes of defect states and to explain the highly efficient photoluminescence of defect states. The large Stokes shift of the defect emission was explained by strong electron-phonon coupling in the nanoparticles. Steady-state and time-resolved photoluminescence spectroscopy indicated two emissive defect states with characteristic emission energies and lifetimes. Change of the surface-to-volume ratio in the nanoparticles affected the relative contribution of the two states, implying that defect emission in higher energy was attributable to surface-related defects. The defect emission in lower energy was attributable to intrinsic defects, which were also present in bulk. The quantum yield of the surface defects was larger than that of the intrinsic defects, which accounted for the unusually high quantum yield of AgIn5S8 nanoparticles, although the origin of emission was the defect states, not the exciton recombination found in typical semiconductor nanoparticles.

  14. Energy transfer and depolarization in the photoluminescence of a plasmonic molecule.

    Science.gov (United States)

    Yin, Tingting; Jiang, Liyong; Dong, Zhaogang; Yang, Joel K W; Shen, Ze Xiang

    2017-02-02

    We report a comprehensive experimental study of the polarization dependence between excitation and photoluminescence (PL) emission from single dolmen-like metallic nanostructures that exhibit both Fano-like and Lorentz-like plasmon resonances. Though the PL spectra of this plasmonic "molecule" also exhibit the Fano and Lorentz signature, the emitted photons do not maintain the same polarization as the excitation. Surprisingly, the degree of depolarization correlates closely to the resonant excitation of the constituent atoms (single nanorod). More specifically, the excitation of a transverse plasmon mode results in a depolarized emission through the longitudinal plasmon modes of the constituent nanorods. In view of the recent evidence of on-resonant plasmon induced excitations in generating hot electrons, our results suggest that depolarized PL emissions could be enhanced through hot-electron decay. Both macroscopic and microscopic mechanisms are proposed to well-understand the excitation wavelength dependent depolarized photoluminescence behaviors in the plasmonic molecule. Our results lay a foundation for applying the depolarized photoluminescence of complex plasmonic nanostructures in polarization engineering.

  15. A novel magnetic/photoluminescence bifunctional nanohybrid for the determination of trypsin.

    Science.gov (United States)

    Xia, Tingting; Ma, Qiang; Hu, Tianyu; Su, Xingguang

    2017-08-01

    In this work, we have designed a novel kind of nanohybrid with magnetic and photoluminescence (PL) property for trypsin detection. The modified magnetic Fe3O4 nanoparticles (MNPs) with polydopamine (PDA) and human serum albumin (HSA) were prepared through a one step self-polymerization under mild condition. The polydopamine (PDA) coating on MNPs can improve the biocompatibility of the MNP-PDA-HAS composite due to its hydrophilicity and multifunctional groups. When MNP-PDA-HSA composite was added into the Anti-HSA modified CdTe QDs (anti-HSA-QDs), HSA on the MNP-PDA-HSA composite was captured by the site of anti-HSA-QDs to form MNP-PDA-HSA/anti-HSA-QDs nanohybrid. Therefore, the photoluminescence of QDs can be quenched by Fe3O4 nanoparticles due to the electron transfer. In the presence of trypsin, the protein (anti-HSA) was digested by trypsin and QDs was separated from the nanohybrid surface. As a result, the photoluminescence intensity of QDs was recovered. The magnetic/luminescent bifunctional nanohybrid displayed excellent analytical performance for the detection of trypsin in the range of 0.5-30μg/mL with a low detection limit of 0.25μg/mL. Copyright © 2017. Published by Elsevier B.V.

  16. Enhancing photoluminescence yields in lead halide perovskites by photon recycling and light out-coupling

    Science.gov (United States)

    Richter, Johannes M.; Abdi-Jalebi, Mojtaba; Sadhanala, Aditya; Tabachnyk, Maxim; Rivett, Jasmine P.H.; Pazos-Outón, Luis M.; Gödel, Karl C.; Price, Michael; Deschler, Felix; Friend, Richard H.

    2016-01-01

    In lead halide perovskite solar cells, there is at least one recycling event of electron–hole pair to photon to electron–hole pair at open circuit under solar illumination. This can lead to a significant reduction in the external photoluminescence yield from the internal yield. Here we show that, for an internal yield of 70%, we measure external yields as low as 15% in planar films, where light out-coupling is inefficient, but observe values as high as 57% in films on textured substrates that enhance out-coupling. We analyse in detail how externally measured rate constants and photoluminescence efficiencies relate to internal recombination processes under photon recycling. For this, we study the photo-excited carrier dynamics and use a rate equation to relate radiative and non-radiative recombination events to measured photoluminescence efficiencies. We conclude that the use of textured active layers has the ability to improve power conversion efficiencies for both LEDs and solar cells. PMID:28008917

  17. Photoluminescence Probing of Complex H2O Adsorption on InGaN/GaN Nanowires.

    Science.gov (United States)

    Maier, Konrad; Helwig, Andreas; Müller, Gerhard; Hille, Pascal; Teubert, Jörg; Eickhoff, Martin

    2017-02-08

    We demonstrate that the complex adsorption behavior of H2O on InGaN/GaN nanowire arrays is directly revealed by their ambient-dependent photoluminescence properties. Under low-humidity, ambient-temperature, and low-excitation-light conditions, H2O adsorbates cause a quenching of the photoluminescence. In contrast, for high humidity levels, elevated temperature, and high excitation intensity, H2O adsorbates act as efficient photoluminescence enhancers. We show that this behavior, which can only be detected due to the low operation temperature of the InGaN/GaN nanowires, can be explained on the basis of single H2O adsorbates forming surface recombination centers and multiple H2O adsorbates forming surface passivation layers. Reversible creation of such passivation layers is induced by the photoelectrochemical splitting of adsorbed water molecules and by the interaction of reactive H3O(+) and OH(-) ions with photoactivated InGaN surfaces. Due to electronic coupling of adsorbing molecules with photoactivated surfaces, InGaN/GaN nanowires act as sensitive nanooptical probes for the analysis of photoelectrochemical surface processes.

  18. Revealing the Origin and History of Lead-White Pigments by Their Photoluminescence Properties.

    Science.gov (United States)

    Gonzalez, Victor; Gourier, Didier; Calligaro, Thomas; Toussaint, Kathleen; Wallez, Gilles; Menu, Michel

    2017-03-07

    The lead white pigment, composed of two main mineral phases cerussite PbCO3 and hydrocerussite 2PbCO3·Pb(OH)2, has been used in paintings since the Antiquity. The study of historical sources revealed that a large variety of lead white qualities were proposed, depending on the degree of sophistication of the pigment synthesis. Investigation of photoluminescence of the two constitutive mineral phases gave insight into the origin of the visible emission of these materials and emphasized the influence of structural defects on their photoluminescence properties. These effects were observed by combining emission and excitation spectra in two-dimensional representations. For each excitation wavelength, between 250 and 400 nm (4.9-3.1 eV), luminescence spectra were collected between 400 and 800 nm (3.1-1.5 eV). Two types of emission-excitation bands were identified: an emission excited in the optical bandgap of the compounds (about 5 eV), which depends on the constitutive phase (2.8 eV in cerussite and 2.1 eV in hydrocerussite), and broad emission bands in the same energy range excited below the optical gap, which are sensitive to the synthesis method and the nature of postsynthesis treatments. It is proposed that this sensitivity of photoluminescence properties of lead-white pigments could be used as fingerprints of their origin and history.

  19. Resonant silicon nanoparticles for enhancement of light absorption and photoluminescence from hybrid perovskite films and metasurfaces.

    Science.gov (United States)

    Tiguntseva, E; Chebykin, A; Ishteev, A; Haroldson, R; Balachandran, B; Ushakova, E; Komissarenko, F; Wang, H; Milichko, V; Tsypkin, A; Zuev, D; Hu, W; Makarov, S; Zakhidov, A

    2017-08-31

    Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites. Here we use low-loss high-refractive-index dielectric (silicon) nanoparticles for improving the optical properties of organo-metallic perovskite (MAPbI3) films and metasurfaces to achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally a 50% enhancement of photoluminescence intensity from a perovskite layer with silicon nanoparticles and 200% enhancement for a nanoimprinted metasurface with silicon nanoparticles on top. Strong increase in light absorption is also demonstrated and described by theoretical calculations. Since both silicon nanoparticle fabrication/deposition and metasurface nanoimprinting techniques are low-cost, we believe that the developed all-dielectric approach paves the way to novel scalable and highly effective designs of perovskite based metadevices.

  20. Synthesis of AgInS2 quantum dots with tunable photoluminescence for sensitized solar cells

    Science.gov (United States)

    Cai, Chunqi; Zhai, Lanlan; Ma, Yahui; Zou, Chao; Zhang, Lijie; Yang, Yun; Huang, Shaoming

    2017-02-01

    Synthesis of quantum dots (QDs) with high photoluminescence is critical for quantum dot sensitized solar cells (QDSCs). A series of high quality AgInS2 QDs were synthesized under air circumstance by the organometallic high temperature method. Feature of tunable photoluminescence of AgInS2 QDs with long lifetime and quantum yields beyond 40% has been achieved, which was mainly attributed to the donor-acceptor pair recombination, contributed above 91% to the whole emission profiles. After ligand exchange with bifunctional linker, water-soluble AgInS2 QDs were adopted as light harvesters to fabricate QDSCs, achieved best PCE of 2.91% (short-circuit current density of 13.78 mA cm-2, open-circuit voltage of 0.47 V, and fill factor of 45%) under one full sun illumination. The improved photovoltaic performance of AgInS2 QDs-based QDSCs is mainly originated from broadened optoelectronic response range up to ∼900 nm, and enhanced photoluminescence with long lifetime and high quantum yield beyond 40%, which provide strong photoresponse ∼40% over the window below 750 nm. The synthetic approach combined with intrinsic defects created by intentionally composition modulation introduces a new approach towards the goal of high performance QDSCs.

  1. Hole transport and photoluminescence in Mg-doped InN

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N.; Ager III, J. W.; Smith III, H. M.; Mayer, M. A.; Yu, K. M.; Haller, E. E.; Walukiewicz, W.; Schaff, W. J.; Gallinat, C.; Koblmuller, G.; Speck, J. S.

    2010-03-24

    Hole conductivity and photoluminescence were studied in Mg-doped InN films grown by molecular beam epitaxy. Because surface electron accumulation interferes with carrier type determination by electrical measurements, the nature of the majority carriers in the bulk of the films was determined using thermopower measurements. Mg concentrations in a"window" from ca. 3 x 1017 to 1 x 1019 cm-3 produce hole-conducting, p-type films as evidenced by a positive Seebeck coecient. This conclusion is supported by electrolyte-based capacitance voltage measurements and by changes in the overall mobility observed by Hall effect, both of which are consistent with a change from surface accumulation on an n-type film to surface inversion on a p-type film. The observed Seebeck coefficients are understood in terms of a parallel conduction model with contributions from surface and bulk regions. In partially compensated films with Mg concentrations below the window region, two peaks are observed in photoluminescence at 672 meV and at 603 meV. They are attributed to band-to-band and band-to-acceptor transitions, respectively, and an acceptor binding energy of ~;;70 meV is deduced. In hole-conducting films with Mg concentrations in the window region, no photoluminescence is observed; this is attributed to electron trapping by deep states which are empty for Fermi levels close to the valence band edge.

  2. The universal photoluminescence behaviour of yellow light emitting (Ga,In)N/GaN heterostructures

    Science.gov (United States)

    Rosales, D.; Ngo, H. T.; Valvin, P.; Lekhal, K.; Damilano, B.; De Mierry, P.; Gil, B.; Bretagnon, T.

    2014-12-01

    We have studied the time-resolved photoluminescence spectra of yellow light emitting (Ga,In)N-based quantum wells grown by metal-organic vapour phase epitaxy on C-plane sapphire substrate for indium compositions ranging up to 23%. The temperature dependent time resolved photoluminescence spectra collected through the 8-300 K range are found to exhibit behaviours very similar to what is reported in literature in samples with different designs (well width, indium composition in the well layer). However, our quantum devices always exhibit a two-mode exponential decay with a long decay time about four to five times longer than the short one, which was not reported so far. The photoluminescence decay times are wavelength-dependent as always found for indium rich quantum well, a behaviour that is interpreted in terms of carrier localisation in local potential minima. The spectral dependence of the decay time, which was fitted using sigmoidal function, gives access to an average decay time, centred at a given energy, with a phenomenological broadening constant. The average splitting between characteristic energies for long and short decay times, and the broadening constants both increase with the indium composition. The average decay time increases exponentially with the product of the well width to indium composition. This quantity is found to be an excellent indicator of the device performance.

  3. Photoluminescence behavior of amber light emitting GaInN-GaN heterostructures

    Science.gov (United States)

    Thi Ngo, Huong; Rosales, Daniel; Gil, Bernard; Valvin, Pierre; Damilano, Benjamin; Lekhal, Kaddour; de Mierry, Philippe

    2015-03-01

    We present an investigation of optical properties of yellow light emitting (Ga,In) N-based devices grown by metalorganic vapor phase epitaxy (MOVPE) on c-plane sapphire with different designs: well width, indium composition up to 23 percent in the well layer. Using time-resolved photoluminescence measurements collected in range of 8-300K, temperature - dependent photoluminescence decays are determined, they exhibit similar behaviors for all samples. These quantum devices always display a two-mode exponential decay with a long decay time and a short one in a ratio about four to five. The photoluminescence intensities measured from low temperature to room temperature give large values of activation temperature that indicate the increasing of the non-radiative recombination rate when the temperature increases. The average decay times are found by a procedure using fitting sigmoidal functions. These decay times increase exponentially with the indium concentration and the well width due to influence of quantum confined Stark effect on these devices. Finally, in order to estimate the performances of our samples, we plotted the decay times obtained versus product of the indium content and the well width together with others published decay times.

  4. Photoluminescence and magnetic circular dichroism of IrQ(ppy){sub 2}-5Cl

    Energy Technology Data Exchange (ETDEWEB)

    Polosan, S., E-mail: Spol68@yahoo.com [National Institute of Materials Physics, Bucharest-Magurele 077125 (Romania); Faculty of Engineering, Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Radu, I.C. [National Institute of Materials Physics, Bucharest-Magurele 077125 (Romania); Tsuboi, T. [Faculty of Engineering, Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)

    2012-04-15

    Photoluminescence and magnetic circular dichroism of the IrQ(ppy){sub 2}-5Cl compound were investigated between 15 and 295 K. These results have been compared with the output files obtained from Density Functional Theory by using the Gaussian 03W software and some additional packages. The experimental results confirm the first triplet state absorption which arises from d to {pi}{sub Q} transition. The temperature dependence photoluminescence have shown a small interaction with the polystyrene, used for dispersion of IrQ(ppy){sub 2}-5Cl compound. The green and red phosphorescence have the same temperature dependence. The MCD spectra, especially at 15 K, reveals the main transitions involved in the Metal-to-Ligand Charge Transfer processes from the Ir towards the two ligands, phenylpyridine and quinoline, respectively. - Highlights: Black-Right-Pointing-Pointer Mixed-ligand of IrQ(ppy){sub 2}-5Cl synthesis with green and red phosphorescence. Black-Right-Pointing-Pointer Photoluminescence and magnetic circular dichroism measurements from 15 to 295 K. Black-Right-Pointing-Pointer Experimental results have been compared with DFT theoretical calculations. Black-Right-Pointing-Pointer Triplet state which arises from d to {pi}{sub Q} transition was experimentally confirmed. Black-Right-Pointing-Pointer Green and red phosphorescence have the same temperature dependence.

  5. Micro-Photoluminescence Confocal Mapping of Single V-Grooved GaAs Quantum Wire

    Institute of Scientific and Technical Information of China (English)

    HUANG Shao-Hua; CHEN Zhang-Hai; BAI Li-Hui; SHEN Xue-Chu; H. H. Tan; L. Fu; M. Fraser; C. Jagadish

    2006-01-01

    We perform the micro-photoluminescence measurement at low temperatures and a scanning optical mapping with high spatial resolution of a single V-grooved GaAs quantum wire modified by the selective ion-implantation and rapid thermally annealing. While the mapping shows the luminescences respectively from the quantum wires and from quantum well areas between quantum wires in general, the micro-photoluminescence at liquid He temperatures reveals a plenty of spectral structures of the PL band for a single quantum wire. The spectral structures are attributed to the inhomogeneity and non-uniformity of both the space structure and compositions of realwires as well as the defects nearby the interface between quantum wire and surrounding quantum well structures.All these make the excitons farther localized in quasi-zero-dimensional quantum potential boxes related to these non-uniformity and/or defects. The results also demonstrate the ability of micro-photoluminescence measurement and mapping for the characterization of both opto-electronic and structural properties of realquantum wires.

  6. Photoluminescence properties of ZnO thin films prepared by DC magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    YANG Bing-chu; LIU Xiao-yan; GAO Fei; MA Xue-long

    2008-01-01

    ZnO thin films were prepared by direct current(DC) reactive magnetron sputtering under different oxygen partial pressures.And then the samples were annealed in vacuum at 450 ℃. The effects of the oxygen partial pressures and the treatment of annealing in vacuum on the photoluminescence and the concentration of six intrinsic defects in ZnO thin films such as oxygen vacancy(Vo),zinc vacancy(VZn), antisite oxygen(OZn), antisite zinc(ZnO), interstitial oxygen(Oi) and interstitial zinc(Zni) were studied. The results show that a green photoluminescence peak at 520 nm can be observed in all the samples, whose intensity increases with increasing oxygen partial pressure; for the sample annealed in vacuum, the intensity of the green peak increases as well. The green photoluminescence peak observed in ZnO may be attributed to zinc vacancy, which probably originates from transitions between electrons in the conduction band and zinc vacancy levels, or from transitions between electrons in zinc vacancy levels and up valence band.

  7. 信息动态%Surface Oxidation and Photoluminescence Properties of Silicon Nanoparticle

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The silicon nanoparticle have been grown by radio-frequency plasmas-enhanced chemical vapor deposition technique and the photoluminescence (PL) of the silicon suspension have been studied by both steady-state and time-resolved photoluminescence spectra. The steady-state PL spectra of the silicon suspension show that a blue PL band around 440 nm is found for the as-prepared silicon suspension emits. An increase of the intensity for the blue band around 440 nm followed by a red photoluminescence centered at 750nm after storing the suspension for two months. The steady-state PL spectra excited by different wavelength and time-resolved PL spectra of the samples demonstrate that the blue PL band with a delaytime of nanosecond order is caused by the band-to-band recombination in Si nanocrystals. The oxidation of the silicon nanoparticle causes the decaytime increasing. The red PL band originates from radiation recombination of carries via defect/surface-related states and the delay-time of which is on the order of microsecond.

  8. Remote sensing of sample temperatures in nuclear magnetic resonance using photoluminescence of semiconductor quantum dots.

    Science.gov (United States)

    Tycko, Robert

    2014-07-01

    Knowledge of sample temperatures during nuclear magnetic resonance (NMR) measurements is important for acquisition of optimal NMR data and proper interpretation of the data. Sample temperatures can be difficult to measure accurately for a variety of reasons, especially because it is generally not possible to make direct contact to the NMR sample during the measurements. Here I show that sample temperatures during magic-angle spinning (MAS) NMR measurements can be determined from temperature-dependent photoluminescence signals of semiconductor quantum dots that are deposited in a thin film on the outer surface of the MAS rotor, using a simple optical fiber-based setup to excite and collect photoluminescence. The accuracy and precision of such temperature measurements can be better than ±5K over a temperature range that extends from approximately 50K (-223°C) to well above 310K (37°C). Importantly, quantum dot photoluminescence can be monitored continuously while NMR measurements are in progress. While this technique is likely to be particularly valuable in low-temperature MAS NMR experiments, including experiments involving dynamic nuclear polarization, it may also be useful in high-temperature MAS NMR and other forms of magnetic resonance. Published by Elsevier Inc.

  9. 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.

  10. 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.

  11. Influence of Parameters of a Printing Plate on Photoluminescence of Nanophotonic Printed Elements of Novel Packaging

    Directory of Open Access Journals (Sweden)

    Olha Sarapulova

    2015-01-01

    Full Text Available In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and offset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of their photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out the formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polypropylene film. The obtained analytical dependencies were used to confirm the explanation of the processes that occur during the fabrication of nanophotonic coverings with offset gravure printing plates. As a result of experimental studies, it was determined that the different character of the dependency of total luminescence intensity of nanophotonic elements from the percentage of a pad is explained by the use of different types of offset gravure printing plates, where the size of raster points remains constant in one case and changes in the other case, while the depth of the printing elements accordingly changes or remains constant. To obtain nanophotonic areas with predetermined photoluminescent properties, the influence of investigated factors on changes of photoluminescent properties of nanophotonic printed surfaces should be taken into consideration.

  12. 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.

  13. The photoluminescent lifetime of polyelectrolytes in thin films formed via layer by layer self-assembly.

    Science.gov (United States)

    Reilly, Roseanne S; Smyth, Ciarán A; Rakovich, Yury P; McCabe, Eithne M

    2009-03-04

    We present results on luminescence lifetime studies of thin multilayer films of polyelectrolyte molecules produced via layer by layer (LbL) electrostatic assembly. We found that, in contrast to common assumptions, LbL films show measurable photoluminescent lifetimes with an average value of 6 ns. Scanning fluorescence lifetime imaging microscopy studies combined with steady-state photoluminescence measurements imply that this lifetime may be due to aggregation of polyelectrolyte molecules during preparation of LbL films. This conclusion has been further confirmed by atomic force microscopy (AFM). AFM images clearly show the presence of 100-200 nm high aggregates on the surface of these films. This aggregation of polyelectrolyte molecules contributes significantly to the experimentally detected luminescence decays of any light-emitting samples attached to LbL film, especially in a single molecule detection regime. To demonstrate this effect we compare photoluminescence lifetime results for CdTe quantum dots deposited on the surface of LbL polyelectrolyte films.

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

    Science.gov (United States)

    Aleksandrzak, Malgorzata; Kukulka, Wojciech; Mijowska, Ewa

    2017-03-01

    The study presents a modification of graphitic carbon nitride (g-C3N4) 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.

  15. Vapor-phase silanization of oxidized porous silicon for stabilizing composition and photoluminescence

    Science.gov (United States)

    Li, Hong-Liang; Zhu, Yingchun; Xu, Dongsheng; Wan, Yong; Xia, Linhua; Zhao, Xiu-song

    2009-06-01

    A vapor-phase deposition approach to the silanization modification of the oxidized porous silicon (PSi) surface using (CH3O)3Si(CH2)3NH2 has been exploited. Standard clean (SC)-1 (NH3H2O/H2O2/H2O, 1:1:5,v/v) and SC-2 [HCl/H2O2/H2O (1:1:6,v/v)] solutions are utilized for the first time to obtain oxidized PSi and have been proved to be a very efficient combination for creating Si-OH species on the PSi surface. After the modification, an amine group terminated surface was successfully created as demonstrated by the contact angle with water, the x-ray photoelectron spectroscopy, and the Fourier transform infrared (FTIR) spectra. The influences of the surface derivatives on the composition stability of the PSi layer and on its photoluminescence properties were investigated by means of FTIR spectra, photoluminescence spectra, and time-resolved photoluminescence measurements.

  16. Enhancement of Photoluminescence Lifetime of ZnO Nanorods Making Use of Thiourea

    Directory of Open Access Journals (Sweden)

    Erdal Sönmez

    2012-01-01

    Full Text Available We have investigated correlation of photoluminescence lifetime between zinc oxide (ZnO nanorods and thiourea-doped ZnO nanorods (tu: CH4N2S. Aqueous solutions of ZnO nanorods were deposited on glass substrate by using pneumatic spray pyrolysis technique. The as-prepared specimens were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and time-resolved photoluminescence spectroscopy (TRPL. The photoluminescence lifetime of ZnO nanorods and ZnO nanorods containing thiourea was determined as =1.56±0.05 ns (2=0.9 and =2.12±0.03 ns (2=1.0, respectively. The calculated lifetime values of ZnO nanorods revealed that the presence of thiourea in ZnO nanorods resulted in increasing the exciton lifetime. In addition to the optical quality of ZnO nanorods, their exciton lifetime is comparable to the longest lifetimes reported for ZnO nanorods. The structural improvement of ZnO nanorods, containing thiourea, was also elucidated by taking their SEM images which show the thinner and longer ZnO nanorods compared to those without thiourea.

  17. Photoluminescence and semiconducting behavior of Fe, Co, Ni and Cu implanted in heavy metal oxide glasses

    Directory of Open Access Journals (Sweden)

    Mohamed A. Marzouk

    2016-07-01

    Full Text Available Transition metal ions (0.5 wt% of Fe2O3, CoO, NiO or CuO doped heavy metal oxide glasses having chemical composition of 60PbO·20Bi2O3·20 MxOy mol% (where MxOy = B2O3 or SiO2 or P2O5 were prepared by conventional melt annealing method. Combined optical and photoluminescence properties have been measured and employed to evaluate the prepared glassy samples. From the absorption edge data, the values of the optical band gap Eopt, Urbach energy (ΔE and refractive index were calculated to estimate semiconducting behavior. Photoluminescence and values of the optical energy gap were found to be dependent on the glass composition. The variations of the photoluminescence intensity, values of optical band gap, Urbach energy and refractive index gave an indication to use the prepared glasses for design of novel functional optical materials with higher optical performance.

  18. Photoluminescence of monocrystalline and stain-etched porous silicon doped with high temperature annealed europium

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Lemus, R; Montesdeoca-Santana, A; Gonzalez-Diaz, B; Diaz-Herrera, B; Hernandez-Rodriguez, C; Jimenez-Rodriguez, E [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida AstrofIsico Francisco Sanchez, 2. 38206 La Laguna, Tenerife (Spain); Velazquez, J J, E-mail: rglemus@ull.es [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez, 2. 38206 La Laguna, Tenerife (Spain)

    2011-08-24

    In this work, for the first time, the photoluminescent emission and excitation spectra of non-textured layers and stain-etched porous silicon layers (PSLs) doped with high temperature annealed europium (Eu) are evaluated. The PSLs are evaluated as a host for rare earth ions and as an antireflection coating. The applied doping process, which consists in a simple impregnation method followed by a high-temperature annealing step, is compatible with the standard processes in the fabrication of solar cells. The results show down-shifting processes with a maximum photoluminescent intensity at 615 nm, related to the transition {sup 5}D{sub 0} {yields} {sup 7}F{sub 2}. Different initial concentrations of Eu(NO{sub 3}){sub 3} are evaluated to study the influence of the rare earth concentration on the photoluminescent intensity. The chemical composition and the morphology of Eu-doped PSLs are examined by means of x-ray dispersion spectroscopy, Fourier-transform infrared spectroscopy and scanning electron microscopy. These Eu-doped layers are considered to be applied as energy converters in silicon-based third generation solar cells.

  19. Photoluminescence from nanoparticles of silicon embedded in an amorphous silicon dioxide matrix

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu-Iwayama, Tsutomu (Aichi Univ. of Education (Japan). Dept. of Materials Science); Nakao, Setsuo; Saitoh, Kazuo (National Industrial Research Inst., Nagoya (Japan)); Itoh, Noriaki (Nagoya Univ. (Japan). Dept. of Physics)

    1994-09-26

    We have investigated visible photoluminescence related to nanometre-sized Si crystals in thermal oxide films grown on a crystalline Si wafer, created by a Si[sup +]-implantation and subsequent annealing in a vacuum at 1100[sup o]C (the temperature at which SiO[sub x] decomposes into Si and SiO[sub 2]). Evidence for the formation of Si nanocrystals by annealing at 1100[sup o]C is presented by transmission electron microscopy. The shape of the emission spectrum of the photoluminescence is found to be independent of both excitation energy and annealing time, while the excitation spectrum of the photoluminescence increases as the photon energy increases and its shape depends on annealing time. The results indicate that the photons are absorbed by nanometre-sized Si crystals, for which the band gap is modified by the quantum confinement, and that the emission of photons is not due to direct electron-hole recombination inside Si nanocrystals but is related to defects probably at the interface between Si nanocrystals and SiO[sub 2]. (Author).

  20. Photoluminescent nanocomposite materials based on SBMA copolymer and CdS

    Science.gov (United States)

    Iovu, M.; Enachescu, M.; Culeac, I.; Verlan, V.; Robu, S.; Bojin, D.; Nistor, Iu.; Cojocaru, I.

    2015-02-01

    We present experimental results on copolymer-based nanocomposite made of styrene with butyl methacrylate (SBMA) (1:1) and inorganic semiconductor CdS. Thin film composite samples have been characterized by UV-Vis absorption and photoluminescent spectroscopy, as well as by transmission electron microscopy. Transmission electron microscope (TEM) examination confirms a relatively narrow distribution of CdS nanoclusters in the SBMA matrix, which covers the range 2-10 nm. On the other side, the average CdS particles size estimated from the position of first excitonic peak in the UV-Vis absorption spectrum was found to be 2.8 nm and 4.4 nm for two samples with different duration of thermal treatment, which is in good agreement with photoluminescence (PL) experimental data. The PL spectrum for CdS nanocrystals is dominated by near-band-edge emission. The relatively narrow line width (40-45 nm) of the main PL band suggests the nanoparticles having narrow size distribution. On the other side, relatively low PL emission from surface trap states at longer wavelengths were observed in the region 500-750 nm indicating on recombination on defects. Key words: nanocomposite, polymer matrix, photoluminescence,

  1. Photoluminescence from silicon nano-particles synthesized by laser-induced decomposition of silane

    Science.gov (United States)

    Botti, S.; Coppola, R.; Gourbilleau, F.; Rizk, R.

    2000-09-01

    This work deals with photoluminescence study of silicon nanoparticles produced by CO2-laser-induced decomposition of SiH4 mixed to helium in a controlled atmosphere reactor. By adjusting the pressure of both reactor and precursor gas and its dilution rate in helium, we were able to control, to a certain extent, the silicon growth rate and hence the particle diameter. This latter was determined by both small angle neutron scattering techniques and high resolution transmission electron microscopy observations. Particles with mean diameter ranging between 3 and 10 nm were submitted to photoluminescence and infrared absorption spectroscopy measurements. The photoluminescence spectra revealed two main peaks at about 1.7 and 2.1 eV. The peak position of the former was insensitive to the change of particle size, while its intensity increased after oxidation. The latter showed, however, a slight size dependence but had undergone a drastic decrease after oxidation. These features enabled us to ascribe the red peak (1.7 eV) to some radiative surface defect, while the yellow peak (2.1 eV) appeared consistent with an emission from an oxygen-related defect such as the nonbridging oxygen hole center.

  2. Photoluminescent properties of SPAN-80 coated intrinsic and extrinsic ZnO nanostructures

    Science.gov (United States)

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

    2016-05-01

    Semiconductor nanostructures catch the attention due to morphology tunable properties. SPAN-80-Capped intrinsic and extrinsic ZnO nanostructures have been synthesized by the simple wet-chemical synthesis route. Structural behavior (morphology and crystallography) and photoluminescence performance of synthesized nanomaterials have been explored as a function of variable SPAN-80 concentration (0.05-0.125%). Crystallographic studies reveal that the prepared products possess wurtzite structure. Electron microscopy infers that the quantum dots are bunched together to form multifaceted morphology for 0.05% SPAN-80 concentration, whereas rectangular shape has been observed for extreme capping concentration. Photoluminescence properties have affected drastically with the introduction of SPAN-80 during the precipitation reaction. Photoluminescent properties of the synthesized nanostructures are strongly dependent on SPAN-80 concentration. Augmentation of capping concentration from 0.05% to 0.075% diminishes the luminescence quantum yield due to increased surface passivation whereas further addition of capping agent beyond the optimum capping concentration (0.075%) enhances the PL intensity due to increased energy transfer from capping shell to the nanostructure core.

  3. Fotoluminescência em materiais com desordem estrutural Photoluminescence in disordered materials

    Directory of Open Access Journals (Sweden)

    P. R. de Lucena

    2004-06-01

    Full Text Available A grande maioria dos estudos fotoluminescentes foram realizados com materiais cristalinos, cuja emissão ocorre em temperaturas criogênicas, limitando a aplicação destes materiais. Por sua vez, determinados sólidos com alta densidade de defeitos (amorfos, como titanatos, tungstatos, zirconatos, entre outros, apresentam fotoluminescência à temperatura ambiente, semelhante à do silício amorfo. Essa descoberta levou à necessidade de se desenvolver novos modelos para explicar o comportamento desses materiais, mais adequados ao estudo desses materiais. Esta revisão tem como objetivo explicar os resultados de fotoluminescência, utilizando uma abordagem teórico-experimental, com base nas recentes pesquisas desta propriedade em óxidos amorfos.The majority of the studies about photoluminescence had been carried out with crystalline materials, whose emission occurs at cryogenic temperatures, limiting the application of these materials. In turn, some amorphous solids, as titanates, tungstates, zirconates, among others, present photoluminescence at room temperature, seemed with silicon. This discovery led to the necessity of developing new models to explain the behavior of these materials. This revision intends to elucidate the results on photoluminescence, using a theoretical-experimental treatment, on the basis of the recent researches of this property in amorphous oxides.

  4. Functionalization of graphene oxide nanostructures improves photoluminescence and facilitates their use as optical probes in preclinical imaging.

    Science.gov (United States)

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Şen Karaman, Didem; Burikov, Sergey A; Dolenko, Tatiana A; Deguchi, Takahiro; Mamaeva, Veronika; Hänninen, Pekka E; Vlasov, Igor I; Shenderova, Olga A; Rosenholm, Jessica M

    2015-06-21

    Recently reported photoluminescent nanographene oxides (nGOs), i.e. nanographene oxidised with a sulfuric/nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (NDs), graphene quantum dots (GQDs), all of which demonstrate a variety of properties that are attractive for biomedical imaging such as low toxicity and stable photoluminescence. In this study, the nGOs were organically surface-modified with poly(ethylene glycol)-poly(ethylene imine) (PEG-PEI) copolymers tagged with folic acid as the affinity ligand for cancer cells expressing folate receptors. The functionalization enhanced both the cellular uptake and quantum efficiency of the photoluminescence as compared to non-modified nGOs. The nGOs exhibited an excitation dependent photoluminescence that facilitated their detection with a wide range of microscope configurations. The functionalized nGOs were non-toxic, they were retained in the stained cell population over a period of 8 days and they were distributed equally between daughter cells. We have evaluated their applicability in in vitro and in vivo (chicken embryo CAM) models to visualize and track migratory cancer cells. The good biocompatibility and easy detection of the functionalized nGOs suggest that they could address the limitations faced with quantum dots and organic fluorophores in long-term in vivo biomedical imaging.

  5. Micro-Photoluminescence (micro-PL) Study of Core Shell GaAs/GaAsSb Nanowires Grown by Self-Assisted Molecular Beam Epitaxy

    Science.gov (United States)

    2015-06-18

    transistor (FET) and light emitting diode (LED) applications. In this thesis, room temperature and low temperature (4K) micro- photoluminescence (micro...public release; distribution is unlimited. Micro- Photoluminescence (micro-PL) Study of Core-Shell GaAs/GaAsSb Nanowires grown by Self-Assisted Molecular...U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 GaAsSb, Core Shell Nanowires, Micro Photoluminescence

  6. Synthesis, structure and photoluminescence of (PLAGH){sub 2}[ZnCl{sub 4}] and comparative analysis of photoluminescence properties with tris(2,2′-bipyridine)ruthenium(II)

    Energy Technology Data Exchange (ETDEWEB)

    Radanović, Mirjana M. [University of Novi Sad, Faculty of Sciences, Novi Sad (Serbia); Jelić, Miodrag G., E-mail: jelicmgm@uns.ac.rs [University of Novi Sad, Faculty of Technical Sciences, Novi Sad (Serbia); Romčević, Nebojša Ž. [University of Belgrade, Institute of Physics, Belgrade (Serbia); Boukos, Nikos [National Centre for Scientific Research “Demokritos”, Institute of Materials Science, Athens (Greece); Vojinović-Ješić, Ljiljana S.; Leovac, Vukadin M. [University of Novi Sad, Faculty of Sciences, Novi Sad (Serbia); Hadžić, Branka B. [University of Belgrade, Institute of Physics, Belgrade (Serbia); Bajac, Branimir M. [University of Novi Sad, Faculty of Technology, Novi Sad (Serbia); Nađ, Laslo F. [University of Novi Sad, Faculty of Technical Sciences, Novi Sad (Serbia); Chandrinou, Chrysoula [National Centre for Scientific Research “Demokritos”, Institute of Materials Science, Athens (Greece); Baloš, Sebastian S. [University of Novi Sad, Faculty of Technical Sciences, Novi Sad (Serbia)

    2015-10-15

    Highlights: • New zinc(II) complex with pyridoxalaminoguanidine was synthesized. • The enhancement of the photoluminescence due to the compound formation was achieved. • Very high photoluminescence of Zn(II) compound was noticed. • Comparative analysis of photoluminescence with tris(2,2′-bipyridine) ruthenium(II) was provided. - Abstract: The first compound of zinc(II) containing pyridoxalaminoguanidine has been synthesized and characterized by elemental analysis, infrared spectra, conductometric measurements and X-ray crystallography. Single crystals of the compound were obtained in the reaction of methanolic solution of zinc(II) chloride and pyridoxalaminoguanidine hydrochloride. In this compound the coordination of chelate ligand is absent and tetrachlorido complex of zinc(II) with pyridoxalaminuguanidinium cation as contraion is obtained. Photoluminescence spectra were measured. Lorentzian multipeak technique was used to determine peak wavelengths and their intensities. Photoluminescence spectroscopy upon 325, 488 and 514 nm laser excitation light was used to obtain results. This novel compound of zinc(II) was compared to the well-known organic light emitting diode material—ruthenium(II) complex with bypiridine i.e., tris(2,2′-bipyridine)ruthenium(II), under the same circumstances and the identical experimental setup. A scheme of energy levels and transitions is proposed to explain the obtained experimental results.

  7. Application of ZnO nanoparticles to enhance photoluminescence in porous silicon and its possible utilization for improving the short wavelength quantum efficiency of silicon solar cell

    Science.gov (United States)

    Verma, Daisy; Kharkwal, Aneeta; Singh, S. N.; Singh, P. K.; Sharma, S. N.; Mehdi, S. S.; Husain, M.

    2014-11-01

    We have formed photoluminescent porous silicon (PS) layers and over which a ZnO layer (hereafter called ZnOPS layers) is deposited. We studied the photoluminescent properties of individual layers as well as the composite layer under excitation with 405 nm wavelength. Using the data of PL a theoretical analysis of a solar cell having such a composite layer of a given photoluminescent conversion efficiency ηPL on the front surface has been done. The condition of a photoluminescent composite layer (ZnOPS) useful for enhancing the spectral response of n+-p-p+ structured silicon solar cell has been identified.

  8. A new stepped tetranuclear copper(II) complex: synthesis, crystal structure and photoluminescence properties.

    Science.gov (United States)

    Gungor, Elif

    2017-05-01

    Binuclear and tetranuclear copper(II) complexes are of interest because of their structural, magnetic and photoluminescence properties. Of the several important configurations of tetranuclear copper(II) complexes, there are limited reports on the crystal structures and solid-state photoluminescence properties of `stepped' tetranuclear copper(II) complexes. A new Cu(II) complex, namely bis{μ3-3-[(4-methoxy-2-oxidobenzylidene)amino]propanolato}bis{μ2-3-[(4-methoxy-2-oxidobenzylidene)amino]propanolato}tetracopper(II), [Cu4(C11H13NO3)4], has been synthesized and characterized using elemental analysis, FT-IR, solid-state UV-Vis spectroscopy and single-crystal X-ray diffraction. The crystal structure determination shows that the complex is a stepped tetranuclear structure consisting of two dinuclear [Cu2(L)2] units {L is 3-[(4-methoxy-2-oxidobenzylidene)amino]propanolate}. The two terminal Cu(II) atoms are four-coordinated in square-planar environments, while the two central Cu(II) atoms are five-coordinated in square-pyramidal environments. The solid-state photoluminescence properties of both the complex and 3-[(2-hydroxy-4-methoxybenzylidene)amino]propanol (H2L) have been investigated at room temperature in the visible region. When the complex and H2L are excited under UV light at 349 nm, the complex displays a strong blue emission at 469 nm and H2L displays a green emission at 515 nm.

  9. Photoluminescent carbon quantum dots as a directly film-forming phosphor towards white LEDs

    Science.gov (United States)

    Zhang, Feng; Feng, Xiaoting; Zhang, Yi; Yan, Lingpeng; Yang, Yongzhen; Liu, Xuguang

    2016-04-01

    Photoluminescent organosilane-functionalized carbon quantum dots (CQDs), 3.0-3.5 nm in diameter, were synthesized via a facile hydrothermal method using citric acid monohydrate as a precursor and N-(3-(trimethoxysilyl) propyl) ethylenediamine as a coordinating and passivation agent. The optical properties of the as-obtained CQDs were investigated in detail. The CQD aqueous solution emits bright blue-white light under ultraviolet (UV) illumination with a quantum yield of 57.3% and high red-green-blue (RGB) spectral composition of 60.1%, and in particular the CQDs exhibit excitation-independent photoluminescence. The CQDs have a narrow size distribution around 3.1 nm and good film-forming ability through simple heat-treatment. By virtue of these excellent optical characteristics and good film-forming ability, a white light-emitting device (LED) was fabricated by combining a UV-LED chip with a single CQD phosphor film, which exhibited cool white light with a CIE coordinate of (0.31, 0.36), a color rendering index of 84 and a correlated color temperature of 6282 K. In addition, the white LED exhibits good optical stability under various working currents and for different working time intervals. Moreover, the interaction between the carbogenic core and surface groups was discussed using the DMol3 program based on density functional theory. This research suggests the great potential of CQDs for solid-state lighting systems and reveals the effect of the surface state on the photoluminescent mechanism of CQDs.

  10. Photoluminescent carbon quantum dots as a directly film-forming phosphor towards white LEDs.

    Science.gov (United States)

    Zhang, Feng; Feng, Xiaoting; Zhang, Yi; Yan, Lingpeng; Yang, Yongzhen; Liu, Xuguang

    2016-04-28

    Photoluminescent organosilane-functionalized carbon quantum dots (CQDs), 3.0-3.5 nm in diameter, were synthesized via a facile hydrothermal method using citric acid monohydrate as a precursor and N-(3-(trimethoxysilyl) propyl) ethylenediamine as a coordinating and passivation agent. The optical properties of the as-obtained CQDs were investigated in detail. The CQD aqueous solution emits bright blue-white light under ultraviolet (UV) illumination with a quantum yield of 57.3% and high red-green-blue (RGB) spectral composition of 60.1%, and in particular the CQDs exhibit excitation-independent photoluminescence. The CQDs have a narrow size distribution around 3.1 nm and good film-forming ability through simple heat-treatment. By virtue of these excellent optical characteristics and good film-forming ability, a white light-emitting device (LED) was fabricated by combining a UV-LED chip with a single CQD phosphor film, which exhibited cool white light with a CIE coordinate of (0.31, 0.36), a color rendering index of 84 and a correlated color temperature of 6282 K. In addition, the white LED exhibits good optical stability under various working currents and for different working time intervals. Moreover, the interaction between the carbogenic core and surface groups was discussed using the DMol(3) program based on density functional theory. This research suggests the great potential of CQDs for solid-state lighting systems and reveals the effect of the surface state on the photoluminescent mechanism of CQDs.

  11. Room-Temperature Large and Reversible Modulation of Photoluminescence by in Situ Electric Field in Ergodic Relaxor Ferroelectrics.

    Science.gov (United States)

    Sun, Hailing; Wu, Xiao; Peng, Deng Feng; Kwok, K W

    2017-10-04

    Ferroelectric oxides with luminescent ions hold great promise in future optoelectronic devices because of their unique photoluminescence and inherent ferroelectric properties. Intriguingly, the photoluminescence performance of ferroelectric ceramics could be modulated by an external electric field. However, researchers face a current challenge of the diminutive extent and degree of reversibility of the field-driven modification that hinder their use in room-temperature practical applications. Within the scope of current contribution in rare-earth-doped bismuth sodium titanate relaxors, the most important information to be noted is the shifting of the depolarization temperature toward room temperature and the resulting considerable enhancement in ergodicity, as evidenced by the dielectric properties, polarization, and strain hysteresis, as well as the in situ Raman/X-ray diffraction studies. After the introduction of 1 mol % Eu, the induced composition and charge disorders disrupt the original long-range ferroelectric macrodomains into randomly dynamic and weakly correlated polar nanoregions, which facilitates a reversible transformation between polar nanoregions and unstable ferroelectric state under an electric field, engendering a large strain. By virtue of this, both the extent and degree of reversibility of photoluminescence modulation are enhanced (∼60%) considerably, and room-temperature in situ tunable photoluminescence response is then achieved under electric field. These should be helpful for the realization of regulating the physical couplings (photoluminescent-ferroelectrics) in multifunctional inorganic ferroelectrics with a high ergodic state by reversibly tuning the structural symmetry.

  12. 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....

  13. C60-Fullerenes: detection of intracellular photoluminescence and lack of cytotoxic effects

    Directory of Open Access Journals (Sweden)

    Carroll David L

    2006-12-01

    Full Text Available Abstract We have developed a new method of application of C60 to cultured cells that does not require water-solubilization techniques. Normal and malignant cells take-up C60 and the inherent photoluminescence of C60 is detected within multiple cell lines. Treatment of cells with up to 200 μg/ml (200 ppm of C60 does not alter morphology, cytoskeletal organization, cell cycle dynamics nor does it inhibit cell proliferation. Our work shows that pristine C60 is non-toxic to the cells, and suggests that fullerene-based nanocarriers may be used for biomedical applications.

  14. Novel photoluminescence-enhancing substrates for image formation of biological objects

    CERN Document Server

    Dovbeshko, G I; Boyko, V V; Gorchev, V F; Karakhin, S O; Gridina, N Ya; Gorelik, V S; Moiseenko, V N

    2012-01-01

    The use of photonic crystals, which were fabricated on the basis of synthetic opals, as substrates for the luminescence microscopy of biological objects has been shown. The spatial distributions of the photoluminescence by DNA clusters excited by 365-nm ultraviolet irradiation on opal surfaces and rough gold substrates have been studied. With the use of blood cells as an example, a possibility for the visualization of biological objects in the case where the nanostructure elements of synthetic opals are applied as labels and image amplifiers has been demonstrated.

  15. Photoluminescence efficiency in wide-band-gap iii-nitride semiconductors and their heterostructures

    OpenAIRE

    Jurkevičius, Jonas

    2016-01-01

    This doctoral thesis presents a study of photoluminescence efficiency in wide-band-gap III-nitride semiconductors. The work is aimed at investigation of efficiency-limiting processes and causes of efficiency droop in AlGaN epilayers and multiple quantum wells. Also, light emission in BGaN epilayers, which are prospective in view of lattice matching in AlGaN-based heterostructures, is investigated. Three mechanisms are revealed to be important for the droop in AlGaN and the dependence of their...

  16. Silk-mediated synthesis and modification of photoluminescent ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Han Jie; Su Huilan, E-mail: hlsu@sjtu.edu.cn; Xu Jia; Song Weiqiang; Gu Yu; Chen Ying [Shanghai Jiao Tong University, State Key Lab of Metal Matrix Composites (China); Moon, Won-Jin [Gwangju Center, Korea Basic Science Institute (Korea, Republic of); Zhang Di, E-mail: zhangdi@sjtu.edu.cn [Shanghai Jiao Tong University, State Key Lab of Metal Matrix Composites (China)

    2012-02-15

    In this article, a bio-inspired silk-mediated method was established to produce natural material-modified photoluminescent zinc oxide nanoparticles (nano-ZnO). Silk fibroin fibers were employed as the reactive substrates to synthesize nano-ZnO, and silk fibroins (SF) were taken as the biocompatible stabilizers to modify dispersed nano-ZnO. As-prepared nano-ZnO were mainly hexagonal phase particles with diameter around 13 nm. The resulting nano-ZnO/SF hybrids displayed orange emission and good biocompatibility in aqueous system.

  17. High Q-factor resonant photoluminescence from Ge-on-insulator micro-disks

    Science.gov (United States)

    Xu, Xuejun; Hashimoto, Hideaki; Yoshida, Keisuke; Sawano, Kentarou; Maruizumi, Takuya

    2016-05-01

    Micro-disk resonators with high Q-factor have been experimentally demonstrated on germanium-on-insulator (GOI). GOI substrates fabricated by direct wafer bonding show better crystal quality that germanium films directly grown on Si. Sharp resonant peaks with Q-factor around 1000-4000 have been observed from micro-disks fabricated on GOI substrate by low-temperature photoluminescence measurements. The light emission properties against pump laser power and device temperature are also investigated. Our results indicating that GOI micro-disks are promising resonators for low threshold, ultra-compact Ge lasers on Si.

  18. Defect States in Copper Indium Gallium Selenide Solar Cells from Two-Wavelength Excitation Photoluminescence Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Soren A.; Dippo, Patricia; Mansfield, Lorelle M.; Glynn, Stephen; Kuciauskas, Darius

    2016-11-21

    We use two-wavelength excitation photoluminescence spectroscopy to probe defect states in CIGS thin films. Above-Eg excitation is combined with a tunable IR bias light that modulates the population of the defect states. We find that IR illumination in the range of 1400-2000 nm (0.62-0.89 eV) causes a reduction of the PL intensity, the magnitude of which scales linearly with IR power. Further, KF post deposition treatment has only a modest influence on the effect of the IR excitation. Initial data suggest that we have developed an optical characterization tool for band-gap defect states.

  19. Anisotropic carrier and exciton confinement in T-shaped quantum wires revealed by magneto-photoluminescence

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Gislason, Hannes; Hvam, Jørn Märcher

    1998-01-01

    The realization of one-dimensional (1D) semiconductor nanostructures with large confinement energies is of importance for device applications. Different techniques such as growth on tilted substrates (Serpentine superlattices) or prepatterned substrates (V-groove quantum wires) and the cleaved-ed...... was revealed by magneto-photoluminescence. We determine here the extension of the T-shaped quantum wire (T-QWR) state in both confining directions [110] and [001] to verify its 1D character, as shown for crescent-shaped wires...

  20. The origin of blue photoluminescence from nc-Si/SiO2 multilayers

    Institute of Scientific and Technical Information of China (English)

    Ma Zhong-Yuan; Xu Ling; Huang Xin-Fan; Chen Kun-Ji; Feng Duan; Guo Si-Hua; Chen De-Yuan; Wei De-Yuan; Yao Yao; Zhou Jiang; Huang Rui; Li Wei; Xu Jun

    2008-01-01

    Intensive blue photoluminescence (PL) was observed at room temperature from the nanocrystalline-Si/SiO2 (ncSi/SiO2) multilayers (MLs) obtained by thermal annealing of SiO/SiO2 MLs for the first time.By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm,the PL peak blueshifts from 457 to 411 nm.Combining the analysis of TEM,Raman and absorption measurement,this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.

  1. 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.

  2. Photoluminescent properties of di(8-hydroxyquinolato) zinc impregnated in nanoporous glass

    Institute of Scientific and Technical Information of China (English)

    Dayuan Xiong(熊大元); Yuyan Liu(刘煜炎); Suihua Yuan(袁绥华)

    2004-01-01

    Photoluminescent properties of a metal-organic complex, di(8-hydroxyquinolato) zinc, impregnated in nanoporous glass were investigated. In comparison with those in the normal organic fluorescent material,the emission band of the impregnated organic phosphor became wider. Blueshift (14 nm) was observed due to π* → n emission transition. The excitation band of the embedded organic phosphor had a larger blueshift and was divided into several sub-bands. The intensity in the short wavelength end of the embedded organic fluorescent material became much stronger.

  3. Characterization and Photoluminescence Properties of Alumina Nanowires Elaborated by Arc-Plasma

    Institute of Scientific and Technical Information of China (English)

    C. Arnoult; X. Devaux; H. Rinnert; M. Vergnat

    2006-01-01

    Ultrafine powders containing alumina nanowires are synthesized by DC arc plasma from pure aluminium metal.Nanowires grow only when reactive gases are composed of nitrogen and less than ten percent of oxygen.Nanowires have the diameters ranging from 20 to 80 nm and lengths ranging from hundreds nanometers to tens of micrometers. A first assumption of the mechanism process is proposed, in which nanowires grow starting directly from the aluminium. Photoluminescence measurements show that the powders have three emission peaks around 435,530 and 750 nm resulting from different kinds of defects such as oxygen vacancies,aluminium interstitial ions and surface defects.

  4. Synthesis, crystal structures and photoluminescence of anthracen- and pyrene-based coumarin derivatives.

    Science.gov (United States)

    Zhang, Hui; Tong, Hao; Zhao, Yuling; Yu, Tianzhi; Zhang, Peng; Li, Jianfeng; Fan, Duowang

    2015-11-01

    Two new anthracen- and pyrene-based coumarin derivatives, 3-(4-(anthracen-10-yl)phenyl)coumarin (4) and 3-(4-(pyrene-1-yl)phenyl)coumarin (5), were synthesized and characterized by FT-IR, (1)H NMR, element analysis and single crystal X-ray crystallography. The UV-vis absorption and photoluminescence spectra of these coumarin derivatives were investigated. The results show that compound 4 and 5 exhibit blue and blue-green emissions, respectively, under ultraviolet light excitation. Compared with the compound 4, the emission peak of compound 5 was bathochromically shifted by about 80 nm due to the more planar structure and larger π-conjugation.

  5. Photoluminescence and energy transfer processes in rare earth ion doped oxide thin films with substrate heating

    Science.gov (United States)

    Xiao, Zhisong; Zhou, Bo; Yan, Lu; Zhu, Fang; Zhang, Feng; Huang, Anping

    2010-02-01

    Tm-Er codoped amorphous aluminum oxide thin films were prepared by pulsed laser deposition. Broadband photoluminescence in the wavelength region of 1400-1700 nm comprised of two emissions at around 1532 and 1620 nm was observed. PL performance was investigated as a function of the substrate-heating temperature. Possible energy transfer processes involved in the heat treatment were discussed and nonradiative decay rates were evaluated, by comparing the inverse of measured lifetimes with the calculated radiative decay rates. Our results suggest that Tm-Er codoped Al 2O 3 thin film might be potential candidate as broadband light sources and amplifiers.

  6. Reversible modulation of gold nanoclusters photoluminescence based on electrochromic poly(methylene blue).

    Science.gov (United States)

    Zhang, Hui; Zhai, Yanling; Dong, Shaojun

    2014-11-01

    Reversible photoluminescence (PL) switches based on a complex of gold nanoclusters and electrochromic poly(methylene blue) (PMB) were realized. The gold nanoclusters PL of hybrid device can be modulated reversibly under electrochemical stimulation. Such an electrochromic device presents several advantages, such as large fluorescence contrast under reduction and oxidation potentials, good reversibility and excellent long-time stability. This simple protocol is anticipated to offer important hints for other nanoclusters and electrochromic materials in the field of photoelectric devices. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Time-resolved photoluminescence of polycrystalline CdTe grown by close-spaced sublimation

    Science.gov (United States)

    Keyes, B.; Dhere, R.; Ramanathan, K.

    1994-06-01

    Polycrystalline CdTe has shown great promise as a low-cost material for thin-film, terrestrial photovoltaic applications, with efficiencies approaching 16% achieved with close-spaced sublimation (CSS)-grown CdTe. Due to the inherent complexities of polycrystalline material, much of the progress in this area has occurred through a slow trial-and-error process. This report uses time-resolved photoluminescence (TRPL) to characterize the CdTe material quality as a function of one basic growth parameter—substrate temperature. This characterization is done for two different glass substrate materials, soda-lime silicate and borosilicate.

  8. Functionalization of hydride-terminated photoluminescent silicon nanocrystals with organolithium reagents.

    Science.gov (United States)

    Höhlein, Ignaz M D; Angı, Arzu; Sinelnikov, Regina; Veinot, Jonathan G C; Rieger, Bernhard

    2015-02-09

    Hydride-terminated photoluminescent silicon nanocrystals (SiNCs) were functionalized with organolithium compounds. The reaction is proposed to proceed through cleavage of Si - Si bonds and formation of a Si - Li surface species. The method yields colloidally stabilized SiNCs at room temperature with short reaction times. SiNCs with mixed surface functionalities can be prepared in an easy two-step reaction by this method by quenching of the Si - Li group with electrophiles or by addressing free Si - H groups on the surface with a hydrosilylation reaction.

  9. 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.

  10. Tuning Photoluminescence Energy and Fine Structure Splitting in Single Quantum Dots by Uniaxial Stress

    Institute of Scientific and Technical Information of China (English)

    DOU Xiu-Ming; SUN Bao-Quan; WANG Bao-Rui; MA Shan-Shan; ZHOU Rong; HUANG She-Song; NI Hai-Qiao; NIU Zhi-Chuan

    2008-01-01

    @@ We report a photoluminescence (PL) energy red-shift of single quantum dots(QDs)by applying an in-plane compressive uniaxial stress along the[110]direction at a liquid nitrogen temperature.Uniaxial stress has an effect not only on the confinement potential in the growth direction which results in the PL shift,but also on the cylindrical symmetry of QDs which can be reflected by the change of the full width at half maximum of PL peak.This implies that uniaxial stress has an important role in tuning PL energy and fine structure splitting of QDs.

  11. Non-Uniformities in Thin-Film Cadmium Telluride Solar Cells Using Electroluminescence and Photoluminescence: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zaunbrecher, K.; Johnston, S.; Yan, F.; Sites, J.

    2011-07-01

    It is the purpose of this research to develop specific imaging techniques that have the potential to be fast, in-line tools for quality control in thin-film CdTe solar cells. Electroluminescence (EL) and photoluminescence (PL) are two techniques that are currently under investigation on CdTe small area devices made at Colorado State University. It is our hope to significantly advance the understanding of EL and PL measurements as applied to CdTe. Qualitative analysis of defects and non-uniformities is underway on CdTe using EL, PL, and other imaging techniques.

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

    Science.gov (United States)

    Nourmohammadi, Abolghasem; Asadabadi, Saeid Jalali; Yousefi, Mohammad Hasan; Ghasemzadeh, Majid

    2012-12-01

    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.

  13. Temperature dependence of continuum and time resolved photoluminescence of germanium nanostructures

    Directory of Open Access Journals (Sweden)

    M Ardyanian

    2011-12-01

    Full Text Available   Germanium nanostructures were generated in the post annealed germanium oxide thin films. Visible and near infrared photoluminescence bands were observed in the samples annealed at 350°C and 400°C, respectively. These different luminescence ranges are attributed to the presence of the defects in oxide matrix and quantum confinement effect in the germanium nanostructures, respectively. Decay time and temperature dependence of the luminescence for different bands were investigated, which confirmed our idea about the origin of the luminescence.

  14. Photoluminescence Intermittency from Single Quantum Dots to Organic Molecules: Emerging Themes

    Science.gov (United States)

    Riley, Erin A.; Hess, Chelsea M.; Reid, Philip J.

    2012-01-01

    Recent experimental and theoretical studies of photoluminescence intermittency (PI) or “blinking” exhibited by single core/shell quantum dots and single organic luminophores are reviewed. For quantum dots, a discussion of early models describing the origin of PI in these materials and recent challenges to these models are presented. For organic luminophores the role of electron transfer, proton transfer and other photophysical processes in PI are discussed. Finally, new experimental and data analysis methods are outlined that promise to be instrumental in future discoveries regarding the origin(s) of PI exhibited by single emitters. PMID:23202909

  15. Structural and Photoluminescence Properties of β-Ga2O3 Nanofibres Fabricated by Electrospinning Method

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian-Guo; ZHANG Zhen-Xing; MA Zi-Wei; DUAN Hui-Gao; GUO Xiao-Song; XIE Er-Qing

    2008-01-01

    We have prepared the β-Ga2Oa nanofibres by electrospinning method followed by calcining in air at 900℃. The morphology and structure of the nanofibres are characterized by field emission scanning electron microscopy(FE-SEM), x-ray diffraction (XRD) and Raman technique. These nanofibres have diameters ranging from 60 to 13Onm and lengths up to several millimetres. Photoluminescence (PL) spectrum under excitation at 325nm shows that these β-Ga2Oa nanofibres have a blue emission peaking at 466nm, which may be attributed to defects such as the oxygen vacancies, gallium vacancies and gallium-oxygen vacancy pairs.

  16. TiO2 controlling photoluminescence of AWO4 (A =Ca,Sr,Ba) nanofilms

    Science.gov (United States)

    Jia, Runping; Zhang, Guoxin; Wu, Qingsheng; Ding, Yaping

    2006-07-01

    AWO4 (A =Ca,Sr,Ba) nanofilms are prepared by a self-inventive technique using collodion to disperse nanoparticles and form film, and their photoluminescence (PL) properties are controlled by a nano-TiO2 doping method. This cannot only reach the results of uniform film and PL enhancement, but also realize a PL increase/decrease shift effect. The PL behaviors of AWO4 nanofilms doped by TiO2 are in good agreement with Gaussion function relation. In addition, there is a positive correlation between the critical concentrations of TiO2 in AWO4-TiO2 nanofilm series and A's ionic potential.

  17. Strong Room-Temperature Photoluminescence from the Novel Adduct of C60 with Aliphatic Amines

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Strong room-temperature photoluminescence from the adducts of C60 reacting with five different aliphatic amines, namely propylethylamine (PPA), n-butyl amine (BTA), n-heptylamine (HPA) and dodecylamine (DDA) and diethylamine (DEA), was firstly found from their toluene solution at relatively shorter wavelength around 519 nm.The fluorescence intensity has a good correlation with the length of n-alkyl group chain, the steric position and concentration of different amines and setting of solution as well as the UV-radiation. Their fluorescence quenching by concentration and by aromatic electron-donor N,N-dimethylaniline (DMA) were first investigated and determined.

  18. Positron annihilation lifetime and photoluminescence studies on single crystalline ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, A [Department of Physics, Bangabasi Morning College, 19 Rajkumar Chakraborty Sarani, Kolkata 700 009 (India); Chakrabarti, Mahuya [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Ray, S K [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur (India); Bhowmick, D; Sanyal, D, E-mail: dirtha@vecc.gov.in [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700064 (India)

    2011-04-20

    The room temperature positron annihilation lifetime for single crystalline ZnO has been measured as 164 {+-} 1 ps. The single component lifetime value is very close to but higher than the theoretically predicted value of {approx} 154 ps. Photoluminescence study (at 10 K) indicates the presence of hydrogen and other defects, mainly acceptor related, in the crystal. Defects related to a lower open volume than zinc vacancies, presumably a complex with two hydrogen atoms, are the major trapping sites in the sample. The bulk positron lifetime in ZnO is expected to be a little less than 164 ps.

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

    Science.gov (United States)

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

    2017-08-01

    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.

  20. Homogeneous linewidth of single InGaAs quantum dot photoluminescence

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Langbein, Wolfgang; Jensen, Jacob Riis

    2000-01-01

    We have used m-photoluminescence spectroscopy with a spectral resolution of 20 meV to measure homogeneous linewidths of single emission lines within an inhomogeneously broadened ensemble of In0.5Ga0.5As/GaAs self-assembled quantum dots. At 10K, a distribution of linewidths peaking around 50 me......V is found, which corresponds to a dephasing time of 26 ps. The shape of the linewidth distribution is similar for dots lying at the high and low-energy tail of the dot ensemble....