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Sample records for excited colour-centre luminescence

  1. On the relationship between luminescence excitation spectra and feldspar mineralogy

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Johnsen, O.

    1996-01-01

    Feldspar minerals can be used as naturally occurring radiation dosemeters, with dose assessment commonly using luminescence techniques. Since many feldspars contain radioactive K-40, knowledge of the mineralogy of the luminescent samples being measured is of high importance. Most feldspars contain...... more than trace amounts of highly luminescent Fe3+ impurities, and this article examines the relationship between features of the luminescence excitation spectrum of this ion with sample mineralogy. It is demonstrated that there is a near linear correspondence between the plagioclase feldspar...

  2. Electric dipole centres and colour centres in natural sodalite

    NARCIS (Netherlands)

    Brom, W.E. van den; Kerssen, J.; Volger, J.

    1974-01-01

    Experiments on an electric dipole centre, exhibiting multiple relaxation, in the natural mineral sodalite, are described. The concentration of the dipole centres is reduced upon X irradiation, whereas simultaneously colour centres and paramagnetic centres arise. Thermal bleaching restores the

  3. Native NIR-emitting single colour centres in CVD diamond

    OpenAIRE

    Gatto Monticone, D; Traina, P.; Moreva, E.; Forneris, J.; Olivero, P.; Degiovanni, I.P.; Taccetti, F.; Giuntini, L.; Brida, G.; Amato, G.; Genovese, M.

    2014-01-01

    Single-photon sources are a fundamental element for developing quantum technologies, and sources based on colour centres in diamonds are among the most promising candidates. The well-known NV centres are characterized by several limitations, thus few other defects have recently been considered. In the present work, we characterize in detail native efficient single colour centres emitting in the near infra-red in both standard IIa single-crystal and electronic-grade polycrystalline commercial ...

  4. Spodumene and garnet luminescence excited by subnanosecond electron beams

    Science.gov (United States)

    Baksht, E. Kh.; Burachenko, A. G.; Solomonov, V. I.; Tarasenko, V. F.

    2011-11-01

    Pulsed cathodoluminescence of spodumene and yttrium-aluminum garnet crystals activated by Mn2+ and Nd3+ ions, respectively, is investigated. The luminescence was excited upon crystal irradiation by electron beams with current densities of 35 and 100 A/cm2 and average electron energy of ˜ 50 keV for 0.1, 0.25, and 0.65 ns. It is demonstrated that the electron beam duration decreased to several tenth of a nanosecond does not lead to essential changes of the mechanisms of pulsed cathodoluminescence excitation and character of its spectrum, but in this case, the intensity of luminescence of the hole centers increases compared with the intracenter luminescence.

  5. Luminescent rise times of inorganic phosphors excited by high intensity ultraviolet light.

    Science.gov (United States)

    Anderson, R J; Ricchio, S G

    1973-11-01

    The relative delay between excitation and luminescence was measured for a number of common inorganic phosphors using short, high intensity excitation pulses. The delays were found to be much shorter than anticipated; on the basis of low intensity pulsed luminescence measurements and were found to be extremely intensity-dependent. Both the luminescence rise and decay times were found to be intensitydependent as well, with the luminescence pulse waveform tending to approach the exciting pulse at the higher excitation intensities.

  6. Influence of excitation power density on temperature dependencies of NaYF4: Yb, Er nanoparticles luminescence spectra

    Science.gov (United States)

    Ustalkov, Sergey O.; Kozlova, Ekaterina A.; Savenko, Olga A.; Mohammed, Ammar H. M.; Kochubey, Vyacheslav I.; Skaptsov, Alexander A.

    2017-03-01

    Upconversion nanoparticles are good candidates for nanothermometry. The wavelength of the excitation and luminescence lie in optical window. The influence of the excitation power density on the luminescence temperature dependences is studded. Ratio of luminescence intensities linearly depends on temperature.

  7. Luminescence and excitation spectra of YAG:Nd{sup 3+} excited by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ning Lixin [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Tanner, Peter A. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)], E-mail: bhtan@cityu.edu.hk; Harutunyan, Vachagan V.; Aleksanyan, Eduard [Yerevan Physics Institute, 2 Alikhanian Brothers Str., 375036 Yerevan (Armenia); Makhov, Vladimir N. [Lebedev Physical Institute, Leninskii Prospect 53, 119991 Moscow (Russian Federation); Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Kirm, Marco [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia)

    2007-12-15

    The low-temperature 4f{sup 2}5d{yields}4f{sup 3} fast emission of Nd{sup 3+} from YAG:Nd{sup 3+} has been studied under excitation by synchrotron radiation. Additionally, 4f{sup 3}{yields}4f{sup 3} luminescence of Nd{sup 3+} has been observed and assigned to transitions from the {sup 2}F(2){sub 5/2} and {sup 4}F{sub 3/2} multiplet terms. The observed experimental spectra of Nd{sup 3+} d-f emission and f-d excitation are well simulated by crystal-field calculations.

  8. Laser-induced incandescence of suspended particles as a source of excitation of dye luminescence

    CERN Document Server

    Zelensky, S

    2003-01-01

    The interaction of pulsed YAG-Nd sup 3 sup + laser radiation with submicron light-absorbing particles suspended in an aqueous solution of Rhodamine 6G is investigated experimentally. The experiments demonstrate that the laser-induced incandescence of suspended particles excites the luminescence of the dissolved dye molecules. The mechanism of the luminescence excitation consists in the reabsorption of the thermal radiation within the volume of the sample cell. On the ground of this mechanism of excitation, a method of measurement of the luminescence quantum yield is proposed and realized. The method requires the knowledge of the geometrical parameters of the cell and does not require the use of reference samples.

  9. LANTHANIDE ENHANCE LUMINESCENCE (LEL) WITH ONE AND TWO PHOTON EXCITATION OF QUANTUM DYES LANTHANIDE (III) - MACROCYCLES

    Science.gov (United States)

    Title: Lanthanide Enhance Luminescence (LEL) with one and two photon excitation of Quantum Dyes? Lanthanide(III)-Macrocycles Principal Author:Robert C. Leif, Newport InstrumentsSecondary Authors:Margie C. Becker, Phoenix Flow Systems Al Bromm, Virginia Commonw...

  10. The luminescence of BaF{sub 2} nanoparticles upon high-energy excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vistovskyy, V. V., E-mail: visvv@gmail.com; Zhyshkovych, A. V.; Halyatkin, O. O.; Voloshinovskii, A. S. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Mitina, N. E.; Zaichenko, A. S. [Lviv Polytechnic National University, 12 S. Bandera St., 79013 Lviv (Ukraine); Rodnyi, P. A. [Saint-Petersburg State Polytechnical University, 29, Polytekhnicheskaya, 195251 Saint-Petersburg (Russian Federation); Vasil' ev, A. N. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Gektin, A. V. [Institute for Scintillation Materials, NAS of Ukraine, 60 Lenina Ave, 61001 Kharkiv (Ukraine)

    2014-08-07

    The dependence of X-ray excited luminescence intensity on BaF{sub 2} nanoparticle size was studied. A sharp decrease of self-trapped exciton luminescence intensity was observed when the nanoparticle size is less than 80 nm. The main mechanism of the luminescence quenching is caused by the escape of electrons from the nanoparticles. Escape of electrons from nanoparticles is confirmed by the considerable increase of luminescence intensity of the polystyrene scintillator with embedded BaF{sub 2} nanoparticles comparing with pure polystyrene scintillator.

  11. Effect of optical excitation energy on the red luminescence of Eu3+ in GaN

    Science.gov (United States)

    Peng, H. Y.; Lee, C. W.; Everitt, H. O.; Lee, D. S.; Steckl, A. J.; Zavada, J. M.

    2005-01-01

    Photoluminescence (PL) excitation spectroscopy mapped the photoexcitation wavelength dependence of the red luminescence (D05→F27) from GaN:Eu. Time-resolved PL measurements revealed that for excitation at the GaN bound exciton energy, the decay transients are almost temperature insensitive between 86 K and 300 K, indicating an efficient energy transfer process. However, for excitation energies above or below the GaN bound exciton energy, the decaying luminescence indicates excitation wavelength- and temperature-dependent energy transfer influenced by intrinsic and Eu3+-related defects.

  12. Luminescence of spodumene and garnet crystals excited by subnanosecond and nanosecond electron beams

    Science.gov (United States)

    Tarasenko, V. F.; Solomonov, V. I.; Polisadova, E. F.; Burachenko, A. G.; Baksht, E. Kh.

    2012-05-01

    The pulsed cathode luminescence of spodumene and yttrium-aluminum garnet crystals activated by Mn2+ and Nd3+ ions, respectively, is studied. Luminescence is excited by the irradiation of the crystals by electron beams with a duration of 0.1, 0.25, 0.65, and 10 ns and a current density of ˜40 and 100 A/cm2 at an electron energy of ˜200 keV. A decrease in the electron beam duration to several tenths of a nanosecond is shown not to cause substantial changes in the excitation mechanisms of pulsed cathode luminescence and its spectrum.

  13. The recombination channels of luminescence excitation in YAG:Yb single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zakharko, Ya.M. [Faculty of Electronics, Ivan Franko National University of Lviv, 107 Tarnavskogo str., Lviv 79017 (Ukraine)], E-mail: zakharko@electronics.wups.lviv.ua; Luchechko, A.P. [Faculty of Electronics, Ivan Franko National University of Lviv, 107 Tarnavskogo str., Lviv 79017 (Ukraine); Ubizskii, S.B. [Lviv Polytechnic National University, 12, Bandera srt., Lviv 79013 (Ukraine); Syvorotka, I.I. [Scientific Research Company ' Carat' , 202, Stryjska str., Lviv 79031 (Ukraine); Martynyuk, N.V. [Lviv Polytechnic National University, 12, Bandera srt., Lviv 79013 (Ukraine); Syvorotka, I.M. [Scientific Research Company ' Carat' , 202, Stryjska str., Lviv 79031 (Ukraine)

    2007-04-15

    Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of Yb{sup 3+} ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the f-f transition at Yb{sup 3+} ion excitation, as well as the mechanism of lifetime shortening for the excited Yb{sup 3+} luminescence have been discussed.

  14. X-ray excited luminescence of polystyrene composites loaded with SrF{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Demkiv, T.M.; Halyatkin, O.O.; Vistovskyy, V.V. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Hevyk, V.B. [Ivano-Frankivsk National Technical University of Oil and Gas, 15 Karpatska St., 76019 Ivano-Frankivsk (Ukraine); Yakibchuk, P.M. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Gektin, A.V. [Institute for Scintillation Materials, NAS of Ukraine, 60 Lenina Ave, 61001 Kharkiv (Ukraine); Voloshinovskii, A.S. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine)

    2017-03-01

    The polystyrene film nanocomposites of 0.3 mm thickness with embedded SrF{sub 2} nanoparticles up to 40 wt% have been synthesized. The luminescent and kinetic properties of the polystyrene composites with embedded SrF{sub 2} nanoparticles upon the pulse X-ray excitation have been investigated. The luminescence intensity of the pure polystyrene scintillator film significantly increases when it is loaded with the inorganic SrF{sub 2} nanoparticles. The film nanocomposites show fast (∼2.8 ns) and slow (∼700 ns) luminescence decay components typical for a luminescence of polystyrene activators (p-Terphenyl and POPOP) and SrF{sub 2} nanoparticles, respectively. It is revealed that the fast decay luminescence component of the polystyrene composites is caused by the excitation of polystyrene by the photoelectrons escaped from the nanoparticles due to photoeffect, and the slow component is caused by reabsorption of the self-trapped exciton luminescence of SrF{sub 2} nanoparticles by polystyrene.

  15. Before there was light : Excited state dynamics in luminescent (nano)materials

    NARCIS (Netherlands)

    Rabouw, F.T.|info:eu-repo/dai/nl/413318036

    2015-01-01

    In this thesis we examine two types of luminescent materials: colloidal semiconductor nanocrystals (also known as quantum dots), and crystals doped with lanthanide ions. These materials convert one color of light to another. By investigating the dynamics of the excited state, we gain new insights

  16. Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra

    Science.gov (United States)

    Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...

  17. X-ray excited optical luminescence studies on the system BaXY (X ...

    Indian Academy of Sciences (India)

    The present paper reports the experimental observations on the x-ray excited optical luminescence (XEOL) along with the afterglow and colour center features found for the barium salts, represented by the formula, Ba, where and are the halides. The system thus consists of four dihalides (BaF2, . . . ,BaI2) and six ...

  18. X-ray excited optical luminescence studies on the system BaXY (X,Y ...

    Indian Academy of Sciences (India)

    For the fluorobromide, the undoped salt gave a broad luminescence peak located at 440 nm, while the ... The undoped BaFBr acquired a bluish pink colour, and the doped salt displayed a pink colour after the .... lived excited state, before decay, allows momentum conservation by the interaction with the lattice, so that the ...

  19. Visible-light-excited and europium-emissive nanoparticles for highly-luminescent bioimaging in vivo.

    Science.gov (United States)

    Wu, Yongquan; Shi, Mei; Zhao, Lingzhi; Feng, Wei; Li, Fuyou; Huang, Chunhui

    2014-07-01

    Europium(III)-based material showing special milliseconds photoluminescence lifetime has been considered as an ideal time-gated luminescence probe for bioimaging, but is still limited in application in luminescent small-animal bioimaging in vivo. Here, a water-soluble, stable, highly-luminescent nanosystem, Ir-Eu-MSN (MSN = mesoporous silica nanoparticles, Ir-Eu = [Ir(dfppy)2(pic-OH)]3Eu·2H2O, dfppy = 2-(2,4-difluorophenyl)pyridine, pic-OH = 3-hydroxy-2-carboxypyridine), was developed by an in situ coordination reaction to form an insoluble dinuclear iridium(III) complex-sensitized-europium(III) emissive complex within mesoporous silica nanoparticles (MSNs) which had high loading efficiency. Compared with the usual approach of physical adsorption, this in-situ reaction strategy provided 20-fold the loading efficiency (43.2%) of the insoluble Ir-Eu complex in MSNs. These nanoparticles in solid state showed bright red luminescence with high quantum yield of 55.2%, and the excitation window extended up to 470 nm. These Ir-Eu-MSN nanoparticles were used for luminescence imaging in living cells under excitation at 458 nm with confocal microscopy, which was confirmed by flow cytometry. Furthermore, the Ir-Eu-MSN nanoparticles were successfully applied into high-contrast luminescent lymphatic imaging in vivo under low power density excitation of 5 mW cm(-2). This synthetic method provides a universal strategy of combining hydrophobic complexes with hydrophilic MSNs for in vivo bioimaging. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Blue luminescence of SrTiO3 under intense optical excitation

    Science.gov (United States)

    Rubano, A.; Paparo, D.; Granozio, F. Miletto; Scotti di Uccio, U.; Marrucci, L.

    2009-11-01

    The blue-green photoluminescence emitted by pure and electron-doped strontium titanate under intense pulsed near-ultraviolet excitation is studied experimentally as a function of excitation intensity and temperature. Both emission spectra and time-resolved decays of the emission are measured and analyzed in the framework of simple phenomenological models. We find an interesting blue-to-green transition occurring for increasing temperatures in pure samples, which is absent in doped materials. The luminescence yield and decay rate measured as a function of temperature can be modeled well as standard activated behaviors. The leading electron-hole recombination process taking place in the initial decay is established to be second order, or bimolecular, in contrast to recent reports favoring a third-order interpretation as an Auger process. The temporal decay of the luminescence can be described well by a model based on two interacting populations of excitations, respectively identified with interacting defect-trapped (possibly forming excitons) and mobile charges. Finally, from the measured doping and sample dependence of the luminescence yield, we conclude that the radiative centers responsible for the luminescence are probably intrinsic structural defects other than bulk oxygen vacancies.

  1. Infrared (IR) stimulated luminescence from feldspars with linearly increasing excitation light intensity

    CERN Document Server

    Bulur, E

    1999-01-01

    IR stimulated luminescence signal from potassium and sodium feldspars were studied by linearly increasing the excitation power from zero to a maximum value during the readout. The peak shaped signals observed in both feldspars could be approximated using a linear combination of three first-order components as deduced by curve fitting. The thermal and radiation dose dependent behavior of the IR-stimulated OSL curves were also studied.

  2. Mechanism of quantum dot luminescence excitation within implanted SiO2:Si:C films.

    Science.gov (United States)

    Zatsepin, A F; Buntov, E A; Kortov, V S; Tetelbaum, D I; Mikhaylov, A N; Belov, A I

    2012-02-01

    Results of the investigation of photoluminescence (PL) mechanisms for silicon dioxide films implanted with ions of silicon (100 keV; 7 × 10(16) cm(-2)) and carbon (50 keV; 7 × 10(15)-1.5 × 10(17) cm(-2)) are presented. The spectral, kinetic and thermal activation properties of the quantum dots (Si, C and SiC) formed by a subsequent annealing were studied by means of time-resolved luminescence spectroscopy under selective synchrotron radiation excitation. Independent quantum dot PL excitation channels involving energy transfer from the SiO(2) matrix point defects and excitons were discovered. A resonant mechanism of the energy transfer from the matrix point defects (E' and ODC) is shown to provide the fastest PL decay of nanosecond order. The critical distances (6-9 nm) of energy transport between the bulk defects and nanoclusters were determined in terms of the Inokuti-Hirayama model. An exchange interaction mechanism is realized between the surface defects (E(s)'-centres) and the luminescent nanoparticles. The peculiarities of an anomalous PL temperature dependence are explained in terms of a nonradiative energy transfer from the matrix excitons. It is established that resonant transfer to the luminescence centre triplet state is realized in the case of self-trapped excitons. In contrast, the PL excitation via free excitons includes the stages of energy transfer to the singlet state, thermally activated singlet-triplet conversion and radiative recombination.

  3. Selective emission and luminescence of Er2O3 under intense laser excitation

    Science.gov (United States)

    Marchenko, V. M.; Iskhakova, L. D.; Studenikin, M. I.

    2013-09-01

    The microstructure of Er2O3 polycrystals synthesised by laser heating is studied. The synthesis of erbium silicate (Er2SiO5) layers was observed upon interaction of Er2O3 and SiO2 melts. The dependences of the selective emission (SE) and luminescence spectra of Er2O3 polycrystals in the range 200 - 1700 nm on the intensity of laser-thermal (at the wavelength λ = 10.6 μm) and resonant laser (λ ≈ 975 nm) excitation are investigated. The emission of heated Er2O3 polycrystals arises as a result of multiphonon relaxation of absorbed energy and is a superposition of the SE at the electronic-vibrational transitions of Er3+ ions and the thermal radiation of the crystal lattice. The shape of the SE spectra of Er2O3 polycrystals in the range 400 - 1700 nm almost does not change upon laser-thermal heating from 300 to 1500 K and subsequent cooling and corresponds to the absorption spectra of Er3+ ions. With increasing temperature, the thermal radiation intensity increases faster than the SE intensity, and the shape of the Er2O3 spectrum becomes closer to the calculated spectrum of a blackbody. The anti-Stokes luminescence spectra of Er3+ ions formed under intense laser excitation of the 4I11/2 level are explained by additional SE caused by heating of the crystal matrix due to the Stokes losses. A difference between the SE and luminescence spectra is observed at low intensities of resonant laser excitation and low temperatures, when only the Stokes luminescence occurs. The temperature dependences of the SE and luminescence spectra of Er2O3 upon laser excitation testify to the fundamental role played by the interaction of the electronic f-shell of Er3+ ions with crystal lattice vibrations in the processes of multiphonon radiative and nonradiative relaxation. The laser-thermal synthesis is promising for inprocess variation of the chemical composition of rare-earth samples.

  4. Luminescence in Conjugated Molecular Materials under Sub-bandgap Excitation

    Energy Technology Data Exchange (ETDEWEB)

    So, Franky [University of Florida

    2014-05-08

    Light emission in semiconductors occurs when they are under optical and electrical excitation with energy larger than the bandgap energy. In some low-dimensional semiconductor heterostructure systems, this thermodynamic limit can be violated due to radiative Auger recombination (AR), a process in which the sub-bandgap energy released from a recombined electron-hole pair is transferred to a third particle leading to radiative band-to-band recombination.1 Thus far, photoluminescence up-conversion phenomenon has been observed in some low dimensional semiconductor systems, and the effect is very weak and it can only be observed at low temperatures. Recently, we discovered that efficient electroluminescence in poly[2-methoxy-5-(2’-ethylhexyloxy)-1, phenylenevinylene] (MEH-PPV) polymer light-emitting devices (PLEDs) at drive voltages below its bandgap voltage could be observed when a ZnO nanoparticles (NPs) electron injection layer was inserted between the polymer and the aluminum electrode. Specifically, emitted photons with energy of 2.13 eV can be detected at operating voltages as low as 1.2 V at room temperature. Based on these data, we propose that the sub-bandgap turn-on in the MEH-PPV device is due to an Auger-assisted energy up-conversion process. The significance of this discovery is three-fold. First, radiative recombination occurs at operating voltages below the thermodynamic bandgap voltage. This process can significantly reduce the device operating voltage. For example, the current density of the device with the ZnO NC layer is almost two orders of magnitude higher than that of the device without the NC layer. Second, a reactive metal is no longer needed for the cathode. Third, this electroluminescence up-conversion process can be applied to inorganic semiconductors systems as well and their operation voltages of inorganic LEDs can be reduced to about half of the bandgap energy. Based on our initial data, we propose that the sub-bandgap turn-on in MEH

  5. Lithium fluoride thin film detectors for low-energy proton beam diagnostics by photoluminescence of colour centres

    Science.gov (United States)

    Montereali, R. M.; Ampollini, A.; Picardi, L.; Ronsivalle, C.; Bonfigli, F.; Libera, S.; Nichelatti, E.; Piccinini, M.; Vincenti, M. A.

    2017-02-01

    Optically transparent LiF thin films thermally evaporated on glass and Si(100) substrates were used for advanced diagnostics of proton beams of energies from 1.4 to 7 MeV produced by a linear accelerator for protontheraphy under development at ENEA C.R. Frascati. The proton irradiation induces the formation of stable colour centres, among them the aggregate F2 and F3 + optically active defects. After exposure of LiF films grown on glass perpendicularly to the proton beams, their accumulated transversal spatial distributions were carefully measured by reading the latent two-dimensional (2-D) fluorescence images stored in the LiF thin layers by local formation of these broad-band visible light-emitting defects with an optical microscope under blue lamp excitation. Taking advantage from the low thickness of LiF thin films and from the linear behaviour of the integrated F2 and F3 + photoluminescence intensities up to the irradiation fluence of ∼5x1015 p/cm2, placing a cleaved LiF film grown on Si substrate with the cutted edge perpendicular to the proton beam, the 2-D fluorescence image of the film surface could allow to obtain the depth profile of the energy released by protons, which mainly lose their energy at the end of the path.

  6. Thermally stimulated luminescence studies in combustion ...

    Indian Academy of Sciences (India)

    Wintec

    Photoluminescence; thermoluminescence; gamma irradiation; colour centres. 1. Introduction. Thermally stimulated luminescence (TSL), also called thermoluminescence (TL), is extensively used as a techni- que in dosimetry. The energy absorbed by a phosphor on being exposed to some ionizing radiation is released as.

  7. Soft X-ray excited optical luminescence from functional organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Sham, T.K., E-mail: tsham@uwo.ca

    2015-10-01

    Highlights: • Many functional organic materials convert X-ray energy into visible light. • The X-ray induced luminescence (XEOL) across an absorption edge can be site and excitation channel specific. • XEOL is composition, morphology, size and crystallinity dependent. • XEOL using the time structure of a synchrotron can reveal the decay and energy transfer dynamics of the sample. • The combined use of XEOL and XAS in the analysis of functional organic materials is illustrated. - Abstract: This brief report reviews some of the recent findings in the study of synchrotron based X-ray excited optical luminescence (XEOL) from representative organic light emitting device (OLED) and related functional organic materials. The systems of interest include Alq{sub 3}, aluminium tris(8-hydroxylquinoline); Ru(bipy){sub 3}{sup 2+}, tris-(2,2-bipyridine) ruthenium(II); Ir(bpy){sub 3}, tris(2-phenyl-bipyridine)iridium; PVK (poly(N-vinylcarbazole)) and [Au{sub 2}(dppe)(bipy)]{sup 2+}, a Au(I) polymer containing 1,2-bis(diphenylphosphino)ethane and the 4,40-bipyridyl ligands, as well as TBPe (2,5,8,11-tetra-tert-butylperylene) polyhedral crystals and fluorescein isothiocyanate (FITC) and FITC-labelled proteins. It is shown that tunable and pulsed X-rays from synchrotron light sources enable the detailed tracking of the optical properties of organic functional materials by monitoring the luminescence in both the energy and time domain as the excitation energy is scanned across an element-specific absorption edge. The use of XEOL and X-ray absorption spectroscopy (XAS) in materials analysis is illustrated.

  8. On the influence of dispersion on the spatial distribution of the intensity of luminescence excited by opposing laser pulses

    Science.gov (United States)

    Martynovich, E. F.; Rudenko, G. V.; Polityko, S. I.

    2009-01-01

    The spatial dynamics of variations in the intensity of the luminescence of quantum systems in crystals of the medium and highest categories of symmetry upon excitation with opposing optical pulses of an arbitrary shape is investigated by numerical simulation methods. It is established that the material dispersion, which is responsible for the dispersion spreading of pulses, has no effect on the shape and width of the envelope of the spatial distribution of the luminescence intensity, as well as on the depth of the luminescence intensity modulation associated with the interference of opposing pulses.

  9. Selectively excited blue luminescence in heavily Mg doped p-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Colton, John S.; Yu, Peter Y.

    2000-12-31

    The emission at {approx}2.8 eV from heavily doped p-GaN, known as the blue luminescence (BL), has been studied by selective excitation using a dye laser tunable between 2.7-3.0 eV. The peak position and intensity of the BL are found to exhibit an unusual dependence on the excitation photon energy. We have explained our results with a shallow-donor and deep-acceptors pair recombination model which includes potential fluctuations induced by heavy doping. We found a ''critical energy'' of {approx}2.8 eV for the BL. Electron-hole pairs with energies above this energy are able to achieve quasi-thermal equilibrium while those with energies below 2.8 eV are strongly ''localized''.

  10. Luminescence of Er3+ doped double lead halide crystals under X-ray, UV, VIS and IR excitation

    Science.gov (United States)

    Serazetdinov, A. R.; Smirnov, A. A.; Pustovarov, V. A.; Isaenko, L. I.

    2017-09-01

    Er3+ doped double lead halide crystals incorporate a number of properties making them interesting for practical use in light conducting materials. X-ray excited luminescence (XRL) spectra, photoluminescence (PL) spectra in region of 1.5-3.5 eV, photoluminescence excitation (PLE) spectra (2.75-5 eV) and anti-stokes luminescence (ASL) spectra were measured at room temperature in KPb2Cl5 (KPC) and RbPb2Br5 (RPB) matrices doped with Er3+ (1%) ions and in KPC doped with Er3++ Yb3+ ions(1:3 ratio concentration). Intraconfigurational f→f transitions are observed in Er3+ ions in most of the cases. The concrete spectrum form is strongly dependent on the excitation energy. Under 980 nm excitation upper Er3+ levels are excited, showing upconversional processes. In case of 313 nm (UV) and 365 nm (VIS) excitation self trapped exciton luminescence was detected in RPB crystal. Additional Yb3+ doping ions strongly increase quantum yield under 980 nm excitation and this doping cause insignificant influence on quantum yield under VIS or UV excitation.

  11. Selective excitation of the yellow and blue luminescence in n- and p-doped Gallium Nitride

    CERN Document Server

    Colton, J S

    2000-01-01

    doping-related potential fluctuations and disorder. Characteristics of the our model for the BL include (a) an Urbach tail, having width E sub 0 = 33 meV, (b) a strong electron-LO phonon coupling occurring with a Frank-Condon shift of approx 180 meV between excitation and emission, (c) a mobility gap at 2.8 eV, separating highly mobile states and highly localized states, and (d) PL-like behavior for excitation energies larger than 2.8 eV, having a blue-shift with increasing excitation energy caused by the increased number of free carriers in the material. GaN is an interesting material: technologically very useful, but still having many unexplained features. Two such features are the broad defect-related luminescence bands: the YL of n-type GaN and the BL of Mg-doped p-type GaN. We have employed selective excitation to investigate these bands. In the case of the YL, most of the previous evidence has supported a recombination model between distant donors and acceptors, most likely a transition involving a shal...

  12. The effect of intensity of excitation on CdSe/ZnS quantum dots: Opportunities in luminescence sensing

    Science.gov (United States)

    Sutter, Jens U.; Birch, David J. S.; Rolinski, Olaf J.

    2011-01-01

    We report changes in the photophysical properties of core-shell type CdSe/ZnS quantum dots (QDs) under optical irradiation. QDs either in aqueous solution or immobilized in a silica sol gel matrix have been excited at different wavelengths and fluxes. Illumination of the sample with 140 fs 700 nm Ti:sapphire laser pulses of the peak power of the order of 4 GW/cm2 caused gradual increase in the luminescence lifetime from an initial value of 3.5 increasing to 4.5 ns and an increase in luminescence intensity by ˜8%. Using about 16 GW/cm2 peak power resulted in a shortening of the luminescence lifetime to 3 ns and a decrease in intensity by ˜75%. Both photobrightening and photodarkening were fully reversible. We discuss the kinetics of photobrightening and photodarkening and investigate the suitability of QDs as luminescence lifetime sensors with tunable parameters.

  13. Three-photon-excited luminescence from unsymmetrical cyanostilbene aggregates: morphology tuning and targeted bioimaging.

    Science.gov (United States)

    Mandal, Amal Kumar; Sreejith, Sivaramapanicker; He, Tingchao; Maji, Swarup Kumar; Wang, Xiao-Jun; Ong, Shi Li; Joseph, James; Sun, Handong; Zhao, Yanli

    2015-05-26

    We report an experimental observation of aggregation-induced enhanced luminescence upon three-photon excitation in aggregates formed from a class of unsymmetrical cyanostilbene derivatives. Changing side chains (-CH3, -C6H13, -C7H15O3, and folic acid) attached to the cyanostilbene core leads to instantaneous formation of aggregates with sizes ranging from micrometer to nanometer scale in aqueous conditions. The crystal structure of a derivative with a methyl side chain reveals the planarization in the unsymmetrical cyanostilbene core, causing luminescence from corresponding aggregates upon three-photon excitation. Furthermore, folic acid attached cyanostilbene forms well-dispersed spherical nanoaggregates that show a high three-photon cross-section of 6.0 × 10(-80) cm(6) s(2) photon(-2) and high luminescence quantum yield in water. In order to demonstrate the targeted bioimaging capability of the nanoaggregates, three cell lines (HEK293 healthy cell line, MCF7 cancerous cell line, and HeLa cancerous cell line) were employed for the investigations on the basis of their different folate receptor expression level. Two kinds of nanoaggregates with and without the folic acid targeting ligand were chosen for three-photon bioimaging studies. The cell viability of three types of cells incubated with high concentration of nanoaggregates still remained above 70% after 24 h. It was observed that the nanoaggregates without the folic acid unit could not undergo the endocytosis by both healthy and cancerous cell lines. No obvious endocytosis of folic acid attached nanoaggregates was observed from the HEK293 and MCF7 cell lines having a low expression of the folate receptor. Interestingly, a significant amount of endocytosis and internalization of folic acid attached nanoaggregates was observed from HeLa cells with a high expression of the folate receptor under three-photon excitation, indicating targeted bioimaging of folic acid attached nanoaggregates to the cancer cell line

  14. Colour centre production in yttria-stabilized zirconia by swift charged particle irradiations

    Science.gov (United States)

    Costantini, Jean-Marc; Beuneu, François; Gourier, Didier; Trautmann, Christina; Calas, Georges; Toulemonde, Marcel

    2004-06-01

    We have studied the colour centre production by swift electron and heavy ion irradiations of yttria-stabilized zirconia (YSZ), i.e. ZrO2:Y with 9.5 mol% Y2O3. For this purpose, we performed irradiations of \\langle 100\\rangle - or \\langle 110\\rangle -oriented YSZ single crystals with 2.5 MeV electrons, 145 MeV 13C, 180 MeV 32S, 200 MeV 58Ni, 230 MeV 79Br, 120 MeV 127I, 200 MeV 127I, 200 MeV 197Au, and 2.6 GeV 238U ions. X-band electron paramagnetic resonance (EPR) and UV-visible optical absorption measurements were used to monitor the point defect formation. The EPR line saturations were measured between 6 and 150 K, in order to obtain the spin-lattice relaxation time (T1). Electron and ion beams produce the same two colour centres: (i) the first one is identified as an F+-type centre (singly ionized oxygen vacancy) with an axial \\langle 100\\rangle symmetry, a small g-factor anisotropy (g_{\\bot }=1.972 and g_{\\parallel }=1.996 ) and long T1 values, (ii) the second one is similar to the well known T-centre (Zr3+ in a trigonal oxygen environment) with an axial \\langle 111\\rangle symmetry and a large g-factor anisotropy (g_{\\bot }=1.855 and g_{\\parallel }=1.986 ), which is also produced by photon irradiations. A broad optical absorption band centred at a wavelength near 500 nm is observed with an absorption coefficient proportional to the volume density of the F+-type centre deduced from the room temperature EPR spectra. Since no change of this band occurs between 10 and 300 K, it indicates that the electron-phonon coupling of this colour centre must be strong, in agreement with an F+-type centre. Owing to the axial \\langle 100\\rangle symmetry and lack of hyperfine structure of the EPR lines of this defect, it is suggested that the first coordination shell must contain one native oxygen vacancy. The plots of the volume density of this centre versus fluence are on the whole rescaled as functions of the number of displacements per atom induced by elastic

  15. X-ray excited luminescence of Ga- and In-doped ZnO microrods by annealing treatment

    Science.gov (United States)

    Li, Qianli; Liu, Xiaolin; Gu, Mu; Huang, Shiming; Zhang, Juannan; Ni, Chen; Liu, Bo; Hu, Yahua; Wu, Qiang; Zhao, Shuning

    2016-10-01

    Ga- and In-doped ZnO microrods were prepared by low temperature hydrothermal process, and the effect of annealing temperature on morphology, crystallization, photoluminescence and X-ray excited luminescence were deeply researched. The results showed that both Ga- and In-doped ZnO microrods were possessed of a good crystalline quality and exhibited an intense visible emission band with a blue-shift under X-ray excitation. This blue-shift of the visible luminescence could be ascribed to the different contributions of the defect emissions, i.e. the increase in the oxygen vacancy (VO) emission and the decrease of the oxygen interstitial (Oi) emission. Moreover, a strong ultraviolet luminescence was also obtained by further hydrogen annealing. It is expected that Ga- and In-doped microrods are promising candidates for development of fast and high-spatial-resolution X-ray imaging detectors.

  16. Colour centres induced in LiF by low-energy electrons

    CERN Document Server

    Baldacchini, G; Montereali, R M; Scacco, A

    1998-01-01

    A detailed study has been carried out on the optical properties of intrinsic colour centres, created in LiF crystals under irradiation with low-penetration 3 keV electrons. The kinetics of the production of F and M centres, determined from optical absorption measurements, exhibits a typical three-stage structure and an evident saturation at high doses. The quantitative evaluation of the kinetic parameters is in excellent agreement with the predictions of the most comprehensive theoretical model. A comparison of the effects of irradiation at different temperatures, determined from absorption and photoluminescence spectra, allows one to deduce the conditions for preferential formation of F sub 2 or F sub 3 sup + defects in LiF crystals. (author)

  17. Selective excitation of the yellow and blue luminescence in n- and p-doped Gallium Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Colton, John Synder [Univ. of California, Berkeley, CA (United States)

    2000-12-01

    GaN is an interesting material: technologically very useful, but still having many unexplained features. Two such features are the broad defect-related luminescence bands: the YL of n-type GaN and the BL of Mg-doped p-type GaN. We have employed selective excitation to investigate these bands. In the case of the YL, most of the previous evidence has supported a recombination model between distant donors and acceptors, most likely a transition involving a shallow donor to a deep acceptor. Our selective excitation experiments have resolved finer structures within the YL. Our results indicate that the YL in bulk samples is related to the YL in film samples. We suggest that selectively excited YL involves recombination at DAP complexes, rather than between spatially distant DAPs (however other recombination channels, including that of distant DAPs may become significant under other excitation conditions). Characteristics of the DAP complexes within our YL model include (a) an electron localization energy of around 60-70 meV, (b) a localized phonon energy of around 40 meV, and (c) excited states of the complex at 200 and 370 meV above the ground state. In the case of the BL, the deep defect responsible for the BL is unknown, and there may not even be a deep defect involved. Also in dispute is the role of potential fluctuations in the properties of the BL. Our results have been explain in a model whereby emission is from DAPs, and significant effects are produced by doping-related potential fluctuations and disorder. Characteristics of the our model for the BL include (a) an Urbach tail, having width E{sub 0} = 33 meV, (b) a strong electron-LO phonon coupling occurring with a Frank-Condon shift of {approx} 180 meV between excitation and emission, (c) a mobility gap at 2.8 eV, separating highly mobile states and highly localized states, and (d) PL-like behavior for excitation energies larger than 2.8 eV, having a blue-shift with increasing excitation energy caused by the

  18. In vivo X-Ray excited optical luminescence from phosphor-doped aerogel and Sylgard 184 composites

    Science.gov (United States)

    Allison, Stephen W.; Baker, Ethan S.; Lynch, Kyle J.; Sabri, Firouzeh

    2017-06-01

    X-Ray excited optical luminescence (XEOL) is a new and noninvasive diagnostic technique suitable for in situ biochemical imaging and disease detection. The X-Ray excited optical luminescence of phosphor doping in crosslinked silica aerogel and Sylgard 184 hosts was investigated in this study. Composite silica aerogels and Sylgard 184 samples of 5%, 15%, and 50% concentrations by weight of La2O2S:Eu phosphor were prepared and inserted subcutaneously in a Sprague-Dawley rat and excited by X-Ray emission at 70 and 100 kV. A fiber optic bundle positioned within 5 mm of the sample collected the luminescence signal and conveyed it to a photomultiplier detector. The signal intensity scaled with dopant concentration. The time dependence of the predominantly red luminescence consisted of 60 cycle bursts of approximately 8 ms duration. The amplitude was modulated at about 10 Hz with a 60% depth. This indicates the time dependence of the X-Ray source. A simulation showed how to observe phosphor decay between individual burst pulses. The emission from the two types of composite samples was easily detected from the outside of the skin layer. Both Sylgard 184 and crosslinked silica aerogels are biocompatible and bio stable materials that could serve a variety of potential XEOL applications. These very strong signals imply potential for creating new In-vivo sensing applications and diagnostic tools.

  19. [Luminescence properties of thenardite activated with Dy3+ under vacuum ultraviolet excitation].

    Science.gov (United States)

    Taximaiti, Yusufu; Ajimu, Abulai; Su, Zong-Cai; Aierken, Sidike

    2011-08-01

    Na2SO4: Dy3+ phosphors were prepared by heating pure natural thenardite (Na2SO4) with DyF3 at 900 degrees C for 25 min in air studied the Luminescence properties of Na2SO4: Dy3+ were studied by synchrotron radiation. Their photoluminescence (PL) spectra were also investigated under vacuum ultraviolet-ultraviolet (VUV-UV) at room temperature. According to the emission spectra, the yellow-blue ratio (Y/B) is different under different concentrations of Dy3+ and the position of excitation. And the excitation spectrum is consisted of strong bands assigned to the 4f9-->4f8 5d transition at 172 nm, the O(2-)- Tm3+ charge transfer band at 165 nm and weak bands assigned to host absorption (138, 245 nm) and the 6 H15/2-->4D7/2, 6H15/2-->6P3/2, and 6H15/2-->6P7/2 transition at 299, 325 and 351 nm respectively.

  20. Large enhancement of X-ray excited luminescence in Ga-doped ZnO nanorod arrays by hydrogen annealing

    Science.gov (United States)

    Li, Qianli; Liu, Xiaoliln; Gu, Mu; Li, Fengrui; Zhang, Juannan; Wu, Qiang; Huang, Shiming; Liu, Si

    2018-03-01

    Highly c-axis oriented and densely packed ZnO:Ga nanorod arrays were fabricated on ZnO-seeded substrates by hydrothermal method, and the effect of hydrogen annealing on their morphology, structure and luminescence properties was investigated in detail. Under ultraviolet or X-ray excitation, an intense ultraviolet luminescence appeared in the hydrogen-annealed samples owing to the formation of a shallow hydrogen donor state, which can sharply activate the reconbination radiation. The luminescence intensity increased with the annealing temperature, and then decreased at a higher temperature due to the dissociation of the hydrogen ion. The optimum concentration and time of hydrogen annealing were acquired simultaneously. It is expected that the ZnO:Ga nanorod array is a promising candidate for application in ultrafast and high-spatial-resolution X-ray imaging detector.

  1. Visible-near-infrared luminescent lanthanide ternary complexes based on beta-diketonate using visible-light excitation.

    Science.gov (United States)

    Sun, Lining; Qiu, Yannan; Liu, Tao; Feng, Jing; Deng, Wei; Shi, Liyi

    2015-11-01

    We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible-light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3 phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401-460 nm), the complexes show characteristic visible (Sm(3+)) as well as near-infrared (Sm(3+), Nd(3+), Yb(3+), Er(3+), Tm(3+), Pr(3+)) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near-infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications. Copyright © 2015 John Wiley & Sons, Ltd.

  2. X-ray excited optical luminescence, photoluminescence, photostimulated luminescence and x-ray photoemission spectroscopy studies on BaFBr:Eu

    CERN Document Server

    Subramanian, N; Govinda-Rajan, K; Mohammad-Yousuf; Santanu-Bera; Narasimhan, S V

    1997-01-01

    The results of x-ray excited optical luminescence (XEOL), photoluminescence (PL), photostimulated luminescence (PSL) and x-ray photoemission spectroscopy (XPS) studies on the x-ray storage phosphor BaFBr:Eu are presented in this paper. Analyses of XEOL, PL and PSL spectra reveal features corresponding to the transitions from 4f sup 6 td sup 1 to 4f sup 7 configurations in different site symmetries of Eu sup 2 sup +. Increasing x-ray dose is seen to lead to a red shift in the maximum of the PL excitation spectrum for the 391 nm emission. The XEOL and XPS spectra do not show any signature of Eu sup 3 sup + in the samples studied by us, directly raising doubts about the model of Takahashi et al in which Eu sup 2 sup + is expected to ionize to Eu sup 3 sup + upon x-ray irradiation and remain stable until photostimulation. XEOL and PSL experiments with simultaneous x-ray irradiation and He - Ne laser excitation as well as those with sequential x-ray irradiation and laser stimulation bring out the competition betwe...

  3. Luminescence of Ce3+ at two different sites in ?-Sr2P2O7 under vacuum ultraviolet-UV and x-ray excitation

    NARCIS (Netherlands)

    Hou, D.; Han, B.; Chen, W.; Liang, H.; Su, Q.; Dorenbos, P.; Huang, Y.; Gao, Z.; Tao, Y.

    2010-01-01

    A series of Ce3+ doped ?-Sr2?2xCexNaxP2O7 phosphor compounds has been prepared using a high-temperature solid-state reaction technique. The luminescence properties under vacuum ultraviolet-UV and x-ray excitation were studied. Luminescence spectra reveal three UV-emitting peaks at about 310, 330,

  4. The position and topography of the human colour centre as revealed by functional magnetic resonance imaging.

    Science.gov (United States)

    McKeefry, D J; Zeki, S

    1997-12-01

    We used a colour Mondrian--an abstract scene with no recognizable objects--and its achromatic version to image the change in blood oxygenation in the brains of 12 human subjects, with the aim of learning more about the position and variability of the colour centre in the human brain. The results showed a consistent association of colour stimulation with activation of an area that is distinct from the primary visual areas, and lies in the ventral occipitotemporal cortex; we refer to it as human V4. The position of human V4, as defined on functional grounds, varies between individuals in absolute terms but is invariably found on the lateral aspect of the collateral sulcus on the fusiform gyrus. There was no indication of lingual gyral activation. In further studies designed to reveal the topographic map within V4, we stimulated the superior and inferior visual fields separately, using the same stimuli. We found that human V4 contains a representation of both the superior and inferior visual fields. In addition, there appears to be retinotopic organization of V4 with the superior visual field being represented more medially on the fusiform gyrus and the inferior field more laterally, the two areas abutting on one another. We find no evidence that suggests the existence of a separate representation of the inferior hemifield for colour in more dorsolateral regions of the occipital lobe.

  5. [X-ray excited luminescence property of ZnS : Au, Cu fine particles synthesized by hydrothermal method].

    Science.gov (United States)

    Xin, Mei; Cao, Wang-He

    2009-08-01

    Highly luminescent ZnS : Au, Cu X-ray phosphor fine particles synthesized by hydrothermal method is reported for the first time and its photoluminescence (PL) and X-ray excited luminescence (XEL) properties were studied in detail. With direct hydrothermal treatment at 200 degrees C for 12 h, the average gain size of samples is about 15 nm; the synthesized sphere-like nanocrystals with well dispersity and narrow gain size distribution show cubic structure. After baking in argon at 1 000 degrees C for 1h the sample agglomerate size is about 1-2 microm and the roughly spherical fine particles show pure hexagonal structure. The PL and XEL spectra of all the samples show a broad emission band and an intense emission band in the range of 400-600 nm. The maximum XEL intensity of sample directly synthesized by hydrothermal treatment was observed when Cu/Zn and Cu/Al were 3 x 10(-5) and 2, respectively. In this condition, the strongest PL emission was observed for the direct synthesized sample being further baked in argon at 900 degrees C for 1 h and the PL peak was centered at about 529 nm. The strongest XEL emission was observed for the direct synthesized sample being further baked in argon at 1 000 degrees C for 1h and the XEL peak was centered at about 445 and 513 nm, respectively. In the meantime, the XEL intensity increased about ten times compared with that directly synthesized without baking. The difference between PL and XEL spectra is due to its different excitation mechanism. The luminescence mechanism and different excitation mechanism of PL and XEL were discussed. The red shift of XEL spectrum with directly synthesized sample was observed with increasing the Cu/Zn. The reason can also be explained by the luminescence mechanism and excitation mechanism of XEL.

  6. Green luminescence and excited state thermalization in Er-doped gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Seo, J. T.; Hoemmerich, U. H. [Hampton University, Hampton, VA (United States); Steckl, A. J.; Birkhahn, B. R. [University of Cincinnati, Cincinnatii, OH (United States); Zavada, J. M. [US Army European Research Office, London (United Kingdom)

    2006-09-15

    The optical properties in the {sup 2}H{sub 11/2} and {sup 4}S{sub 3/2} to {sup 4}I{sub 15/2} channels of Er-doped GaN have been investigated. The GaN:Er was grown on Si substrates by solid-source molecular beam epitaxy. The resulting Er concentration was {approx}2 x 10{sup 20} cm{sup -3}, and the unintentional oxygen impurity was observed to be {approx}10{sup 20} cm{sup -3}. Optical spectroscopy revealed that the lifetime decay at the {sup 4}S{sub 3/2} state was mainly due to a strong thermalization between the {sup 2}H{sub 11/2} and the {sup 4}S{sub 3/2} states. The green luminescence ({sup 4}S{sub 3/2} and {sup 2}H{sub 11/2} {yields} {sup 4}I{sub 15/2}) efficiency at 300 K was much higher than 56 %. Photoluminescence and lifetime measurements with different excitation channels suggest the existence of multiple Er-sites in GaN.

  7. Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+),Yb(3+)-doped rare-earth microparticles.

    Science.gov (United States)

    Ma, Xiaowei; Kang, Fei; Xu, Feng; Feng, Ailing; Zhao, Ying; Lu, Tianjian; Yang, Weidong; Wang, Zhe; Lin, Min; Wang, Jing

    2013-01-01

    Cerenkov luminescence imaging (CLI) has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs), which can be dually excited by Cerenkov luminescence (CL) resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration. Yb(3+)- and Er(3+)- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models. the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results. this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.

  8. Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+,Yb(3+-doped rare-earth microparticles.

    Directory of Open Access Journals (Sweden)

    Xiaowei Ma

    Full Text Available Cerenkov luminescence imaging (CLI has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs, which can be dually excited by Cerenkov luminescence (CL resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration.Yb(3+- and Er(3+- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD, scanning electron microscopy (SEM, and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models.the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results.this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.

  9. Fabrication of bright and thin Zn₂SiO₄ luminescent film for electron beam excitation-assisted optical microscope.

    Science.gov (United States)

    Furukawa, Taichi; Kanamori, Satoshi; Fukuta, Masahiro; Nawa, Yasunori; Kominami, Hiroko; Nakanishi, Yoichiro; Sugita, Atsushi; Inami, Wataru; Kawata, Yoshimasa

    2015-07-13

    We fabricated a bright and thin Zn₂SiO₄ luminescent film to serve as a nanometric light source for high-spatial-resolution optical microscopy based on electron beam excitation. The Zn₂SiO₄ luminescent thin film was fabricated by annealing a ZnO film on a Si₃N₄ substrate at 1000 °C in N₂. The annealed film emitted bright cathodoluminescence compared with the as-deposited film. The film is promising for nano-imaging with electron beam excitation-assisted optical microscopy. We evaluated the spatial resolution of a microscope developed using this Zn₂SiO₄ luminescent thin film. This is the first report of the investigation and application of ZnO/Si₃N₄ annealed at a high temperature (1000 °C). The fabricated Zn₂SiO₄ film is expected to enable high-frame-rate dynamic observation with ultra-high resolution using our electron beam excitation-assisted optical microscopy.

  10. Time dependence of the luminescence intensity in CdBr2: AgCl,PbBr2 crystals under N2-laser excitation at room temperature

    Science.gov (United States)

    Bolesta, I. M.; Kalivoshka, B. M.; Karbovnyk, I. D.; Lesivtsiv, V. M.; Novosad, I. S.; Novosad, S. S.; Rovetskyy, I. M.; Velgosh, S. R.

    2014-12-01

    Results of optical-luminescence studies of polydoped photochromic CdBr2: AgCl,PbBr2 crystals are presented. It is shown that the luminescence decrease vs. time under N2-laser excitation in the range of A-band of Pb2+ absorption is due to photochemical reactions. The empirical model describing the decrease of the luminescence related to silver impurities due to photochemical processes is suggested. Model parameters (trapping cross-section — σ — and the amount of centres destroyed by irradiation — β) were determined using the comparative analysis of experimental and calculated luminescence decay curves.

  11. Role of the electronically excited-state hydrogen bonding and water clusters in the luminescent metal-organic framework.

    Science.gov (United States)

    Sui, Xiao; Ji, Min; Lan, Xin; Mi, Weihong; Hao, Ce; Qiu, Jieshan

    2013-05-20

    The electronically excited state and luminescence property of metal-organic framework Zn(3-tzba)(2,2'-bipy)(H2O)·nH2O have been investigated using the density functional theory (DFT) and time-dependent DFT (TDDFT). The calculated geometry and infrared spectra in the ground state are consistent with the experimental results. The frontier molecular orbitals and electronic configuration indicated that the origin of luminescence is attributed to a ligand-to-ligand charge transfer (LLCT). We theoretically demonstrated that the hydrogen bond H47···O5═C is weakened in the excited state S1; the weakening of the excited-state hydrogen bonding should be beneficial to the luminescence. To explore the effect of the water clusters on the luminescence, we studied four complexes Zn(3-tzba)(2,2'-bipy)(H2O)·3H2O, Zn(3-tzba)(2,2'-bipy)(H2O)·2H2O, Zn(3-tzba)(2,2'-bipy)(H2O)·H2O, and Zn(3-tzba)(2,2'-bipy)(H2O). The results reveal that the presence of water should play an important role in the emission characteristics of the MOF. Also, the UV-vis absorption and emission spectra of Zn(3-tzba)(2,2'-bipy)(H2O)·3H2O are in good agreement with the experimental results.

  12. Luminescence and excited state dynamics of Bi{sup 3+} centers in Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St. Petersburg (Russian Federation); Lipińska, L. [Institute of Electronic Materials Technology, Wólczyńska 133, 01919 Warsaw (Poland); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Schulman, L.S. [Physics Department, Clarkson University, Potsdam, NY 13699-5820 (United States); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Physics, University of Bydgoszcz, Weyssenhoffa 11, 85072 Bydgoszcz (Poland); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Zhydachevskii, Ya. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Lviv Polytechnic National University, Bandera 12, 79646 Lviv (Ukraine)

    2015-11-15

    Photoluminescence of Y{sub 2}O{sub 3}:Bi nanopowder synthesized by the modified sol–gel method is studied using time-resolved luminescence spectroscopy in the 4.2–300 K temperature range. Bi{sup 3+} ions are substituted for Y{sup 3+} ions in two different crystal lattice sites, one having S{sub 6} symmetry (Bi(S{sub 6})) and the other C{sub 2} symmetry (Bi(C{sub 2})). The luminescence characteristics of these two centers are found to have strongly different electron–phonon interactions. The luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers peak at 3.04 eV and 2.41 eV, respectively, and arise from the radiative decay of the triplet relaxed excited state (RES) of Bi{sup 3+} ions. The model and structure of the RES, responsible for the luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers in Y{sub 2}O{sub 3}:Bi, as well as radiative and nonradiative processes, taking place in the excited states of these centers, are investigated. The parameters of the triplet RES (the separation between the metastable and radiative levels and probabilities of radiative and nonradiative transitions from these levels) are determined. Low-temperature quenching of the triplet luminescence of these centers is explained by nonradiative quantum tunneling transitions from the metastable minima of their triplet RES to closely located defect- or exciton-related levels. - Highlights: • Photoluminescence of Bi{sup 3+} centers of two types in Y{sub 2}O{sub 3}:Bi is investigated. • Bi(S{sub 6}) and Bi(C{sub 2}) centers reveal strongly different electron–phonon interaction. • Radiative and nonradiative processes in their triplet excited states are clarified. • Low-temperature luminescence quenching in Bi(S{sub 6}) and Bi(C{sub 2}) centers is studied. • New fast weak ≈2.9 eV emission is suggested to arise from Bi(C{sub 2}) centers.

  13. SrAl2O4:Eu2+ (1%) luminescence under UV, VUV and electron beam excitation

    Science.gov (United States)

    Nazarov, M.; Mammadova, S.; Spassky, D.; Vielhauer, S.; Abdullayeva, S.; Huseynov, A.; Jabbarov, R.

    2018-01-01

    This paper reports the luminescence properties of nanosized SrAl2O4:Eu2+ (1%) phosphors. The samples were prepared by combustion method at 600 °C, followed by annealing of the resultant combustion ash at 1000 °C in a reductive (Ar + H2) atmosphere. X-ray diffraction (XRD), photo luminescence (PL) and cathodoluminescence (CL) analysis and thermal stimulated luminescence (TSL) method were applied to characterize the phosphor. For the first time a peak at 375 nm was observed in CL spectra of SrAl2O4:Eu2+ (1%) nanophosphors. Luminescence excitation spectra analysis have shown that this peak is related to crystal defects. Also in TSL curve one strong peak was observed in the region above room temperature (T = 325 K), which is attributed to lattice defects, namely oxygen vacancies. A green LED was fabricated by the combination of the SrAl2O4:Eu2+ (1%) nanosized phosphor and a 365 nm UV InGaN chip.

  14. Optimising the separation of quartz and feldspar optically stimulated luminescence using pulsed excitation

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Thomsen, Kristina Jørkov

    2010-01-01

    In luminescence dating, the two most commonly used natural minerals, quartz and feldspar, are exposed to different dose rates in the natural environment, and so record different doses. The luminescence signals also have different stabilities. For accurate dosimetry, the signals from these two...... minerals must be separated, either by physical separation of the mineral grains, or by instrumental separation of the luminescence signals. The luminescence signals from quartz and feldspar have different luminescence lifetimes under pulsed optical stimulation. This difference in lifetime can be used...... OSL intensity ratio is at a maximum. By using these parameters with an additional infrared (IR) stimulation at 175 °C before measurement (to further reduce the feldspar signal intensity), we obtain a factor of 25 enhancement in signal separation compared to that from a conventional prior-IR CW...

  15. Using radiation intensity dependence on excitation level for the analysis of surface plasmon resonance effect on ZnO luminescence

    Science.gov (United States)

    Rumyantsev, S. I.; Tarasov, A. P.; Briskina, C. M.; Ryzhkov, M. V.; Markushev, V. M.; Lotin, A. A.

    2015-10-01

    For the analysis of ZnO luminescence the system of rate equations (SRE) was proposed. It contains a set of parameters that characterizes processes participating in luminescence: zone-zone excitation, excitons formation and recombination, formation and disappearance of photons and surface plasmons (SP). It is shown that experimental ZnO microstructure radiation intensity dependence on photoexcitation level can be approximated by using SRE. Thus, the values of these parameters can be estimated and used for luminescence analysis. This approach was applied for the analysis of ZnO microfilms radiation with different thickness of Ag island film covering. It was revealed that the increase of cover thickness leads to the increase of losses and decrease of probability of photons to SP conversion. In order to take into account visible emission, rate equations for levels populations in band-gap and for corresponding photons and SP were added to SRE. By using such SRE it is demonstrated that the form of visible luminescence intensity dependence on excitation level (P) like P1/3, as obtained elsewhere [1], is possible only in case of donor-acceptor pairs existence. The proposed approach was applied for consideration of experimental results obtained in [5-8] taking into account their interpretation of these results based on assumption about transfer of electrons from defect level in ZnO band-gap to metal and then to conduction band in ZnO. Results of performed calculations using modified SRE revealed that effects observed in these papers can exist under only low pumping level. This result will be experimentally checked later.

  16. Spectral characteristics of intense red luminescence in Pr:Y2O3 nanophosphor on UV excitation

    Science.gov (United States)

    Mishra, Kavita; Dwivedi, Y.; Rai, A.; Rai, S. B.

    2012-12-01

    Detailed structural and spectroscopic characterizations of Pr:Y2O3 nanophosphor have been carried out. On ultraviolet light (at 266 nm) excitation, intense red emission along with weak emissions in blue, green and infrared regions have been observed. The phenomena for the observed emission have been thoroughly explained in the present work and it was finally concluded that the direct excitation through low-lying 4f15d band of Pr3+ ions and through the conduction band of Y2O3 nanophosphor are the main channels for the observed emissions. The calculated quantum efficiency (QE) for the red emission is found to be ~80 % while the CIE coordinates are (0.65, 0.34) quite close to the standard values. These studies clearly indicate that Pr:Y2O3 nanophosphors are promising and futuristic red luminescent material for the development of various display devices and UV detectors. Time resolved spectroscopy has been further used to investigate luminescence dynamics.

  17. Monte Carlo simulation on teaching of luminescence and excited states decay kinetics; Simulacao Monte Carlo no ensino de luminescencia e cinetica de decaimento de estado excitado

    Energy Technology Data Exchange (ETDEWEB)

    Winnischofer, Herbert; Araujo, Marcio Peres de; Dias Junior, Lauro Camargo; Novo, Joao Batista Marques [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

    2010-07-01

    A software based in the Monte Carlo method have been developed aiming the teaching of important cases of mechanisms found in luminescence and in excited states decay kinetics, including: multiple decays, consecutive decays and coupled systems decays. The Monte Carlo Method allows the student to easily simulate and visualize the luminescence mechanisms, focusing on the probabilities of the related steps. The software CINESTEX was written for FreeBASIC compiler; it assumes first-order kinetics and any number of excited states, where the pathways are allowed with probabilities assigned by the user. (author)

  18. Luminescence Color Tuning by Regulating Electrostatic Interaction in Light-Emitting Devices and Two-Photon Excited Information Decryption.

    Science.gov (United States)

    Ma, Yun; Liu, Shujuan; Yang, Huiran; Zeng, Yi; She, Pengfei; Zhu, Nianyong; Ho, Cheuk-Lam; Zhao, Qiang; Huang, Wei; Wong, Wai-Yeung

    2017-03-06

    It is well-known that the variation of noncovalent interactions of luminophores, such as π-π interaction, metal-to-metal interaction, and hydrogen-bonding interaction, can regulate their emission colors. Electrostatic interaction is also an important noncovalent interaction. However, very few examples of luminescence color tuning induced by electrostatic interaction were reported. Herein, a series of Zn(II)-bis(terpyridine) complexes (Zn-AcO, Zn-BF4, Zn-ClO4, and Zn-PF6) containing different anionic counterions were reported, which exhibit counterion-dependent emission colors from green-yellow to orange-red (549 to 622 nm) in CH2Cl2 solution. More importantly, it was found that the excited states of these Zn(II) complexes can be regulated by changing the electrostatic interaction between Zn2+ and counterions. On the basis of this controllable excited state, white light emission has been achieved by a single molecule, and a white light-emitting device has been fabricated. Moreover, a novel type of data decryption system with Zn-PF6 as the optical recording medium has been developed by the two-photon excitation technique. Our results suggest that rationally controlled excited states of these Zn(II) complexes by regulating electrostatic interaction have promising applications in various optoelectronic fields, such as light-emitting devices, information recording, security protection, and so on.

  19. Terbium luminescence in alumina xerogel fabricated in porous anodic alumina matrix under various excitation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gaponenko, N. V., E-mail: nik@nano.bsuir.edu.by [Belarusian State University of Informatics and Radioelectronics (Belarus); Kortov, V. S. [Yeltsin Ural Federal University (Russian Federation); Orekhovskaya, T. I.; Nikolaenko, I. A. [Belarusian State University of Informatics and Radioelectronics (Belarus); Pustovarov, V. A.; Zvonarev, S. V.; Slesarev, A. I. [Yeltsin Ural Federal University (Russian Federation); Prislopski, S. Ya. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)

    2011-07-15

    Terbium-doped alumina xerogel layers are synthesized by the sol-gel method in pores of a porous anodic alumina film 1 {mu}m thick with a pore diameter of 150-180 nm; the film is grown on a silicon substrate. The fabricated structures exhibit terbium photoluminescence with bands typical of trivalent terbium terms. Terbium X-ray luminescence with the most intense band at 542 nm is observed for the first time for such a structure. Morphological analysis of the structure by scanning electron microscopy shows the presence of xerogel clusters in pore channels, while the main pore volume remains unfilled and pore mouths remain open. The data obtained confirm the promising applications of fabricated structures for developing matrix converters of X-rays and other ionizing radiations into visible light. The possibilities of increasing luminescence intensity in the matrix converter are discussed.

  20. X-ray-excited optical luminescence of protein crystals: a new tool for studying radiation damage during diffraction data collection.

    Science.gov (United States)

    Owen, Robin L; Yorke, Briony A; Pearson, Arwen R

    2012-05-01

    During X-ray irradiation protein crystals radiate energy in the form of small amounts of visible light. This is known as X-ray-excited optical luminescence (XEOL). The XEOL of several proteins and their constituent amino acids has been characterized using the microspectrophotometers at the Swiss Light Source and Diamond Light Source. XEOL arises primarily from aromatic amino acids, but the effects of local environment and quenching within a crystal mean that the XEOL spectrum of a crystal is not the simple sum of the spectra of its constituent parts. Upon repeated exposure to X-rays XEOL spectra decay non-uniformly, suggesting that XEOL is sensitive to site-specific radiation damage. However, rates of XEOL decay were found not to correlate to decays in diffracting power, making XEOL of limited use as a metric for radiation damage to protein crystals. © 2012 International Union of Crystallography

  1. Enhancement of the intensity ratio of ultraviolet to visible luminescence with increased excitation in ZnO nanoparticles deposited on porous anodic alumina

    Science.gov (United States)

    Bousslama, Wiem; Sieber, Brigitte; Elhouichet, Habib; Gelloz, Bernard; Addad, Ahmed; Férid, Mokhtar

    2013-12-01

    Porous anodic alumina (PAA), with large pore diameters (up to 100 nm), was used as a substrate for the growth of ZnO nanostructures. Almost unstrained ZnO nanoparticles of less than 8 nm in size were prepared by the spin-on method and annealed at 500 °C. Excitonic recombination is found to dominate the ultraviolet band. The ZnO nanoparticles have a high deep level emission at low excitation which becomes negligible at high excitation, as deduced from photoluminescence measurements. This large increase of the ultraviolet to visible luminescence ratio with excitation is ascribed to the variation of the ultraviolet and of the visible luminescence with excitation intensity. Non-radiative Auger recombination becomes dominant at high excitation. It is also shown that the PAA substrate improves the internal quantum efficiency of the ZnO nanoparticles achieved by the sol-gel method. At low excitation, the luminescence intensity drops by a factor of 3 between 13 and 300 K, leading to an estimate of the internal quantum efficiency as high as 30%.

  2. A visible-light-excited europium(III) complex-based luminescent probe for visualizing copper ions and hydrogen sulfide in living cells

    Science.gov (United States)

    Wang, Yiren; Wang, Huan; Yang, Mei; Yuan, Jingli; Wu, Jing

    2018-01-01

    Development of visible-light-excited lanthanide (III) complex-based luminescent probes is highly appealing due to their superiority of less damage to the living biosystems over the conventional UV-light-excited ones. In this work, a visible-light-excited europium (III) complex-based luminescent probe, BPED-BHHCT-Eu3+-BPT, has been designed and synthesized by conjugating the Cu2+-binding N,N-bis(2-pyridylmethyl)ethanediamine (BPED) to a tetradentate β-diketone ligand 4,4‧-bis(1″,1″,1″,2″,2″,3″,3″-heptafluoro-4″,6″-hexanedione-6″-yl)chlorosulfo-o-terphenyl (BHHCT) and coordinating with a coligand 2-(N,N-diethylanilin-4-yl)-4,6-bis(pyrazol-1-yl)-1,3,5-triazine) (BPT) for the time-gated luminescence detection of Cu2+ ions and hydrogen sulfide (H2S) in living cells. BPED-BHHCT-Eu3+-BPT exhibited a sharp excitation peak at 407 nm and a wide excitation window extending to beyond 460 nm. Upon its reaction with Cu2+ ions, the luminescence of BPED-BHHCT-Eu3+-BPT was efficiently quenched, which could be reversibly restored by the addition of H2S due to the strong affinity between Cu2+ ions and H2S. The "on-off-on" type luminescence behavior of BPED-BHHCT-Eu3+-BPT towards Cu2+ ions and H2S enabled the sensing of the two species with high sensitivity and selectivity. The performances of BPED-BHHCT-Eu3+-BPT for visualizing intracellular Cu2+ ions and H2S were investigated, and the results have demonstrated the practical applicability of the probe for molecular imaging of cells.

  3. Extremely slow relaxation process of a yellow-luminescence-related state in GaN revealed by two-wavelength excited photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Zanardi Ocampo, J.M.; Kamata, N.; Okamoto, W.; Yamada, K. [Saitama Univ. (Japan). Dept. of Functional Materials Science; Hoshino, K.; Someya, T.; Arakawa, Y. [Tokyo Univ. (Japan). Research Center for Advanced Science and Technology

    2001-11-08

    In addition to detection of nonradiative recombination centers by a below-gap excitation (BGE) technique at steady state, we have studied the time-response of both donor-acceptor pair luminescence and yellow luminescence (YL) in GaN after switching off the BGE light. An extremely slow recovery of YL with a time constant of up to 28 s was observed, which is interpreted as a relaxation process of electrons from the state chosen by a BGE energy of 1.17 eV. The dependence of recovery time on the BGE energy and on the above-gap and below-gap excitation power densities became clear for the first time; it reflects the carrier recombination dynamics including YL among below-gap states. (orig.)

  4. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    Science.gov (United States)

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-08-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760-1120 nm wavelength range.

  5. Tunable luminescence mediated by energy transfer in Tm3+/Dy3+ co-doped phosphate glasses under UV excitation

    Science.gov (United States)

    Chen, Yong; Chen, Guohua; Liu, Xiangyu; Yuan, Changlai; Zhou, Changrong

    2017-11-01

    Tm3+/Dy3+ co-doped phosphate glasses for white light-emitting diodes were synthesized by a conventional melting-quenching method. A spectroscopic research based on optical, photoluminescence spectrum and decay time curves in Tm3+/Dy3+ co-doped phosphate glasses was carried out. The color of luminescence could be tuned by altering the concentrations of Tm3+ ions. Under UV light excitation, the CIE chromaticity coordinates (0.3471, 0.3374) and color correlate temperature (CCT = 4866.21 K) close to the standard white-light illumination (0.333, 0.333 and CCT = 5454.12 K) could be achieved in 0.4 Tm3+/0.6 Dy3+ (mol %) co-doped glass sample. The decrease of the Dy3+ emission decay time in existence of Tm3+ ascertained that non-radiative energy transfer from Dy3+ to Tm3+ occurred. Moreover, the research of energy transfers between Dy3+ and Tm3+ based on the Inokuti-Hirayama model revealed that an electric quadrupole-quadrupole interaction might be the predominant mechanism participated in the energy transfer. This finding suggests that the as-prepared Tm3+/Dy3+ co-doped phosphate glasses may be promising candidate for white LEDs and other display devices.

  6. [Luminescence properties of thenardite activated with Tm3+ under vacuum ultraviolet excitation].

    Science.gov (United States)

    Yusufu, Taximaiti; Abulai, Ajimu; Niyazi, Keyoumu; Su, Zong-Cai; Sidike, Aierken

    2011-02-01

    The Na2 SO4 : Tm3+ phosphor was synthesized by the high temperature solid state reaction method in air. The crystalline structure was examined by X-ray diffraction (XRD). Narrow bands observed in emission spectra were well identified with the electronic transitions within the 4f12 configurations of Tm3+, and the excitation spectrum is consisted of strong bands assigned to the 4f12 --> 4f11 5d transition at 183 nm, the O(2-)-Tm3+ charge transfer band at 170 nm and weak bands assigned to host absorption (130, 223 and 258 nm). In addition, the authors also found that the content of Tm3+ in the 8-16 mg concentration range caused quenching.

  7. The Upconversion Luminescence of Er3+/Yb3+/Nd3+ Triply-Doped β-NaYF4 Nanocrystals under 808-nm Excitation

    Directory of Open Access Journals (Sweden)

    Lijiao Tian

    2014-11-01

    Full Text Available In this paper, Nd3+–Yb3+–Er3+-doped β-NaYF4 nanocrystals with different Nd3+ concentrations are synthesized, and the luminescence properties of the upconversion nanoparticles (UCNPs have been studied under 808-nm excitation for sensitive biological applications. The upconversion luminescence spectra of NaYF4 nanoparticles with different dopants under 808-nm excitation proves that the Nd3+ ion can absorb the photons effectively, and the Yb3+ ion can play the role of an energy-transfer bridging ion between the Nd3+ ion and Er3+ ion. To investigate the effect of the Nd3+ ion, the decay curves of the 4S3/2 → 4I15/2 transition at 540 nm are measured and analyzed. The NaYF4: 20% Yb3+, 2% Er3+, 0.5% Nd3+ nanocrystals have the highest emission intensity among all samples under 808-nm excitation. The UC (upconversion mechanism under 808-nm excitation is discussed in terms of the experimental results.

  8. Use of radiation intensity dependence on excitation level for the analysis of surface plasmon resonance effect on ZnO luminescence

    Science.gov (United States)

    Rumyantsev, Stepan; Tarasov, Andrey; Briskina, Charus; Ryzhkov, Mikhail; Markushev, Valery; Lotin, Andrey

    2016-01-01

    For the analysis of ZnO luminescence, a set of rate equations (SRE) is proposed. It contains a set of parameters that characterize processes participating in luminescence: zone-zone excitation, excitons formation and recombination, formation and disappearance of photons, surface plasmons (SP), and phonons. It is shown that experimental ZnO microstructure radiation intensity dependence on photoexcitation levels can be approximated by using SRE. This approach was applied for the analysis of ZnO microfilm radiation with different thicknesses of Ag island film covering. It was revealed that the increase of cover thickness leads to an increase of losses and a decrease of the probability of photon-to-SP conversion. In order to take into account visible emission, rate equations for level populations in the bandgap and for corresponding photons and SPs were added to the SRE. By using such an SRE, it is demonstrated that the form of visible luminescence intensity dependence on excitation level (P) like P, as obtained elsewhere, is possible only if donor-acceptor pairs exist. The proposed approach was also applied for consideration of experimental results obtained in several papers taking into account the interpretation of these results based on assumptions about the transfer of electrons from the defect level in the ZnO bandgap to metal and then to the conduction band.

  9. Luminescence excitation characteristics of Ca-, Na- and K-aluminosilicates (feldspars), in the stimulation range 20-500 eV: optical detection of XAS

    CERN Document Server

    Poolton, N R J; Quinn, F M; Pantos, E; Andersen, C E; Bøtter-Jensen, L; Johnsen, O; Murray, A S

    2003-01-01

    We demonstrate that the visible/UV luminescence from common feldspar crystals (NaAlSi sub 3 O sub 8 , KAlSi sub 3 O sub 8 and CaAl sub 2 Si sub 2 O sub 8) can be used to detect detailed L-edge and associated near-edge absorption structure of the main constituent atoms (Ca, K, Na, Al, Si), when exciting in the energy range 20-500 eV. Comparisons of the spectral features are drawn with similar measurements made on the associated materials SiO sub 2 , Al sub 2 O sub 3 and CaCO sub 3. The potential for using optically detected x-ray absorption spectroscopy as a method for identifying the luminescent components of mixed mineral samples is considered.

  10. Excitation of luminescence of the nanoporous bioactive nanocrystalline carbonate-substituted hydroxyapatite for early tooth disease detection

    Science.gov (United States)

    Goloshchapov, D. L.; Minakov, D. A.; Domashevskaya, E. P.; Seredin, P. V.

    This paper deals with the luminescence characteristics of an analogue of the mineral component of dental enamel of the nanocrystalline B-type carbonate-substituted hydroxyapatite (CHAP) with 3D defects (i.e. nanopores of ∼2-5 nm) on the nanocrystalline surface. The laser-induced luminescence (LIL) of the synthesized CHAP samples was in the range of ∼515 nm (∼2.4 eV) and is due to CO3 groups replacing the PO4 group. It was found that the intensity of the luminescence of the CHAP is caused by structurally incorporated CO3 groups in the HAP structure. Furthermore, the intensity of the luminescence also decreases as the number of the above intracentre defects (CO3) in the apatite structure declines. These results are potentially promising for developing the foundations for precise methods for the early detection of caries in human solid dental tissue.

  11. Application of multi-step excitation schemes for detection of actinides and lanthanides in solutions by luminescence/chemiluminescence laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Izosimov, I. [Joint Institute for Nuclear Research, Joliot Curie 6, Dubna 141980 (Russian Federation)

    2016-07-01

    The use of laser radiation with tunable wavelength allows the selective excitation of actinide/lanthanide species with subsequent registration of luminescence/chemiluminescence for their detection. This work is devoted to applications of the time-resolved laser-induced luminescence spectroscopy and time-resolved laser-induced chemiluminescence spectroscopy for the detection of lanthanides and actinides. Results of the experiments on U, Eu, and Sm detection by TRLIF (Time Resolved Laser Induced Fluorescence) method in blood plasma and urine are presented. Data on luminol chemiluminescence in solutions containing Sm(III), U(IV), and Pu(IV) are analyzed. It is shown that appropriate selectivity of lanthanide/actinide detection can be reached when chemiluminescence is initiated by transitions within 4f- or 5f-electron shell of lanthanide/actinide ions corresponding to the visible spectral range. In this case chemiluminescence of chemiluminogen (luminol) arises when the ion of f element is excited by multi-quantum absorption of visible light. The multi-photon scheme of chemiluminescence excitation makes chemiluminescence not only a highly sensitive but also a highly selective tool for the detection of lanthanide/actinide species in solutions. (author)

  12. Luminescence of YbP{sub 3}O{sub 9} upon excitation in the UV-VUV range

    Energy Technology Data Exchange (ETDEWEB)

    Stryganyuk, G [HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Trots, D [HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Berezovskaya, I [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya doroga, 65080 Odessa (Ukraine); Shalapska, T [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Street, 79005 Lviv (Ukraine); Voloshinovskii, A [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Street, 79005 Lviv (Ukraine); Dotsenko, V [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya doroga, 65080 Odessa (Ukraine); Zimmerer, G [Institute of Experimental Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2007-08-29

    X-ray powder diffraction and luminescence spectral-kinetic studies have been performed for ytterbium metaphosphate (YbP{sub 3}O{sub 9}) in the 12-290 K temperature range. The diffraction investigation has shown YbP{sub 3}O{sub 9} to be of monoclinic P 2{sub 1}/c structure at T = 12-290 K. Charge transfer luminescence originating from Yb{sup 3+} ion has been revealed. The carrier confinement within the Yb{sup 3+} charge transfer state is pronounced at T = 12 K. A tendency has been revealed for charge carriers in YbP{sub 3}O{sub 9} to be localized in a trapped exciton state at room temperature. The quenching mechanisms for Yb{sup 3+} charge transfer luminescence and processes competing with the formation of the Yb{sup 3+} charge transfer state are discussed.

  13. Plasmons excited in a large dense silver nanoparticle layer enhance the luminescence intensity of organic light emitting diodes

    Science.gov (United States)

    Fukuura, Tomohiro

    2015-08-01

    We observe that a layer of large (∼300 nm in diameter) closely packed (∼15 nm interparticle separation) silver nanoparticles separated by a spacer layer at least 50-nm thick from a 30-nm-thick Alq3 layer results in the enhancement of bulk luminescence efficiency in the Alq3 layer. To study the potential for practical application of this long-range luminescence enhancement, an organic light-emitting diode (OLED) was fabricated with the silver nanoparticle layer serving as the enhancement element. This device exhibits a luminescence efficiency 4.5 times stronger than that of a similar device with no silver nanoparticle layer. If such an enhancement is applied to deep-blue emissive materials, the efficiency should reach the levels required for practical use. This combination could lead to the broad use of OLEDs in displays and lighting.

  14. Excitation of luminescence of the nanoporous bioactive nanocrystalline carbonate-substituted hydroxyapatite for early tooth disease detection

    Directory of Open Access Journals (Sweden)

    D.L. Goloshchapov

    Full Text Available This paper deals with the luminescence characteristics of an analogue of the mineral component of dental enamel of the nanocrystalline B-type carbonate-substituted hydroxyapatite (CHAP with 3D defects (i.e. nanopores of ∼2–5 nm on the nanocrystalline surface. The laser-induced luminescence (LIL of the synthesized CHAP samples was in the range of ∼515 nm (∼2.4 eV and is due to CO3 groups replacing the PO4 group. It was found that the intensity of the luminescence of the CHAP is caused by structurally incorporated CO3 groups in the HAP structure. Furthermore, the intensity of the luminescence also decreases as the number of the above intracentre defects (CO3 in the apatite structure declines. These results are potentially promising for developing the foundations for precise methods for the early detection of caries in human solid dental tissue.

  15. The effect of pea chloroplast alignment and variation of excitation wavelenght on the circulary polarized chlorophyll luminescence

    NARCIS (Netherlands)

    Barzda, V.; Ionov, M.; Amerongen, van H.; Gussakovsky, E.E.; Shahak, Y.

    2004-01-01

    Circularly polarized luminescence (CPL) is a powerful technique to study the macroorganization of photosynthetic light-harvesting apparatus in vivoand in vitro. It is particularly useful for monitoring environmental stress induced molecular re-organization of thylakoid membranes in green leaves. The

  16. Luminescent properties of Yb-doped LaSc{sub 3}(BO{sub 3}){sub 4} under VUV excitation

    Energy Technology Data Exchange (ETDEWEB)

    Guerassimova, N.; Kamenskikh, I. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Krasikov, D. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation)], E-mail: kdn@nm.ru; Mikhailin, V. [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, 119992 Moscow (Russian Federation); Zagumennyi, A.; Koutovoi, S.; Zavartsev, Yu. [Laser Crystals Department, General Physics Institute of RAS, Vavilova str. 38, 119991 Moscow (Russian Federation); Pedrini, C. [Laboratoire de Physico-Chimie des Materiaux Luminescents, Universite Claude Bernard Lyon-1, UMR 5620 CNRS, 69622 Villeurbanne (France)

    2007-04-15

    Ytterbium doped borate crystals are promising laser media, e.g. in LaSc{sub 3}(BO{sub 3}){sub 4} (LSB) matrices large distance between ytterbium ions results in reduced concentration quenching of the ytterbium f-f luminescence [Petermann, K., Fagundes-Peters, D., Johansen, O., Mond, M., Peters, V., Romero, J.J., Kutovoi, S., Speiser, J., Giesen, A., 2005. Highly Yb-doped oxides for thin-disc lasers. J. Crystal Growth 275, 135-140]. Yb{sup 3+} ions in complex oxides in addition to the 4f {yields} 4f transitions often manifest fast charge transfer luminescence (CTL) in the UV-visible range. In some borates it was not observed at all, like in orthoborates of Sc, Y and La [Van Pieterson, L., Heeroma, M., de Heer, E., Meijerink, A., 2000. Charge transfer luminescence of Yb{sup 3+}. J. Lumin. 91, 177-193]; in haloborates Sr{sub 2}B{sub 5}O{sub 9}X, where X = Cl, Br, the UV/visible luminescence was attributed to ytterbium CTL though it looked substantially different from other matrices [Dotsenko, V.P., Berezovskaya, I.V., Pyrogenko, P.V., Efryushina, N.P., Rodniy, P.A., Eijk van, C.W.E., Sidorenko, A.V., 2002. Valence states and luminescence properties of ytterbium ions in strontium haloborates. J. Solid State Chem. 166, 271-276]; while in oxyborate Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} 'classical' CTL was observed [Jubera, V., Garcia, A., Chaminade, J.P., Guillen, F., Sablayrolles, Jean, Fouassier, C., 2007. Yb{sup 3+} and Yb{sup 3+}-Eu{sup 3+} luminescent properties of the Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} phase. J. Lumin. 124(1), 10-14]. In this work the luminescence properties of another borate, namely LSB doped by Yb are presented.

  17. Controllable synthesis of Zn/Cd(ii) coordination polymers: dual-emissive luminescent properties, and tailoring emission tendency under varying excitation energies.

    Science.gov (United States)

    Xing, Kai; Fan, Ruiqing; Gao, Song; Wang, Xinming; Du, Xi; Wang, Ping; Fang, Ru; Yang, Yulin

    2016-03-21

    Based on a new asymmetric semi-rigid V-shaped tricarboxylate ligand 3-(2',3'-dicarboxylphenoxy)benzoic acid (H3dpob), a series of zinc/cadmium(ii) coordination polymers, {[Cd(Hdpob)(H2O)3]·H2O}n (1), [Cd(Hdpob)(bib)]n (2), [Zn(Hdpob)(bib)0.5]n (3), {[Cd1.5(dpob)(2,2'-bipy)]·0.5H2O}2n (4) and {[Cd3(dpob)2(4,4'-bipy)2]·3H2O}n (5) [bib = 1,4-bis(1-imidazolyl)benzene; 2,2'-bipy = 2,2'-bipyridine; 4,4'-bipy = 4,4'-bipyridine], have been successfully synthesized via hydro(solvo)thermal reactions. 1 forms a three dimensional (3D) supramolecular structure linked by two types of intermolecular hydrogen bonds based on zig-zag 1D chains, whereas 2 and 3 are obtained with a similar 2D layer structure by the same ligands and further connected into a 3D structure through hydrogen bonds. 4 displays a homochiral 2D structure though two achiral ligands 2,2'-bipy and H3dpob, which contains right-handed helical infinite chains. 5 is a 3D structure containing 2D metal-pyridine layer motifs, which are further pillared by beaded dpob(3-) ligands to complete the structure and form a 6-connected pcu (primitive cubic) net. In DMSO solvent, 1-5 illustrate dual-emission properties but have different low-energy emission (LE) intensities relatively. Extraordinarily, the difference resulting from central metals between 2 and 3 makes the intensity of LE dramatically enhanced and quenched. In this regard, the luminescence of 2 and 3 can be tuned between blue and green regions by varying the excitation light, and the tuning tendency can be tailored with inverse directions. Comparing their tunable-sensitivity to energy quantitatively, the theoretical calculation displays that 3 (4.29%) is little higher than 2 (3.59%) in a relative lower excitation wavelength zone. Meanwhile, five coordination polymers show distinct luminescence thermochromism in the solid state. When the temperature decreases from 298 K to 77 K, the red-shift from blue/green to the pure yellow light region is highlighted. The

  18. Formation of luminescent emitters by intense laser radiation in transparent media

    Science.gov (United States)

    Martynovich, E. F.; Kuznetsov, A. V.; Kirpichnikov, A. V.; Pestryakov, Efim V.; Bagayev, Sergei N.

    2013-05-01

    The formation of luminescent colour centres in the LiF crystal under the action of femtosecond pulses of the first harmonic of a Ti : sapphire laser is experimentally studied. The experiments were carried out at low- and high-aperture focusing of radiation. The effect of both single pulses and multi-pulse trains on the crystals was studied. Channelling of laser radiation in the waveguides, induced by the filaments of the first pulses, is found. The multiphoton mechanism of interband absorption is confirmed. The optimal conditions of laser impact for designing luminescent emitters in the LiF crystal are determined.

  19. Applications of a table-top time-resolved luminescence spectrometer with nanosecond soft X-ray pulse excitation

    Czech Academy of Sciences Publication Activity Database

    Brůža, P.; Pánek, D.; Fidler, V.; Benedikt, P.; Čuba, V.; Gbur, T.; Boháček, Pavel; Nikl, Martin

    2014-01-01

    Roč. 61, č. 1 (2014), s. 448-451 ISSN 0018-9499 R&D Projects: GA ČR GA13-09876S Institutional support: RVO:68378271 Keywords : LiCaAlF 6 * luminescence * scintillators * soft x-ray * SrHfO 3 * time-resolved spectroscopy * ZnO :Ga Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2014

  20. Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation.

    Science.gov (United States)

    Küçük, N; Ayvacikli, M; Akça, S; Yüksel, M; Guinea, J Garcia; Karabulut, Y; Canimoglu, A; Topaksu, M; Can, N

    2017-09-01

    Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB2O4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce(3+) were obtained from RL results. Changing the Ce and La concentration of 0.01-0.1wt% leads to an increase in RL and CL intensities of Ce(3+) and La(3+) ions and also CL emission spectra of ZnB2O4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB2O4 has the highest intense whereas La doped ZnB2O4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M. W. [DESY (Deutsches Elektronen-Synchrotron), FS-PEX, Notkestrasse 85, 22607 Hamburg (Germany); Yiu, Y. M., E-mail: yyiu@uwo.ca; Sham, T. K. [Department of Chemistry, University of Western Ontario, London, ON N6A5B7 (Canada); Ward, M. J. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Liu, L. [Institute of Functional Nano and Soft Materials (FUNSOM) and Soochow University-Western University Center for Synchrotron Radiation Research, Soochow University, Suzhou, Jiangsu, 215123 (China); Hu, Y. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N2V3 (Canada); Zapien, J. A. [Center Of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Liu, Yingkai [Institute of Physics and Electronic Information, Yunnan Normal University, Kunming, Yunnan, 650500 (China)

    2014-11-21

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  2. Investigation of the mechanisms of upconversion luminescence in Ho{sup 3+} doped CaF{sub 2} crystals and ceramics upon excitation of {sup 5}I{sub 7} level

    Energy Technology Data Exchange (ETDEWEB)

    Lyapin, A.A., E-mail: andrei_lyapin@mail.ru [Ogarev Mordovia State University, Bol’shevitskaya street, 68, Saransk (Russian Federation); Kazan Federal University, Kremlevskaja street, 18, Kazan (Russian Federation); Ryabochkina, P.A.; Chabushkin, A.N. [Ogarev Mordovia State University, Bol’shevitskaya street, 68, Saransk (Russian Federation); Ushakov, S.N.; Fedorov, P.P. [General Physics Institute of Russian Academy of Sciences, Vavilova street, 38, Moscow (Russian Federation)

    2015-11-15

    The mechanisms of upconversion luminescence of CaF{sub 2}:Ho crystals and ceramics from {sup 5}F{sub 3}, {sup 5}S{sub 2}({sup 5}F{sub 4}), {sup 5}F{sub 5} and {sup 5}I{sub 6} levels upon excitation of {sup 5}I{sub 7} level of Ho{sup 3+} ions were investigated. Different mechanisms are responsible for the populating and depletion of the energy levels of Ho{sup 3+} ion in CaF{sub 2}:Ho crystals and ceramics upon excitation of {sup 5}I{sub 7} level. The upconversion luminescence from {sup 5}F{sub 3}, {sup 5}F{sub 5}, and {sup 5}I{sub 6} levels in CaF{sub 2}:Ho crystals and ceramics is explained by energy transfer upconversion processes. Our results also confirmed that both excited-state absorption and energy transfer upconversion are responsible for the populating of {sup 5}S{sub 2}({sup 5}F{sub 4}) level. - Highlights: • Crystals and ceramics CaF{sub 2}:Ho were obtained. • Upconversion luminescence of CaF{sub 2}:Ho crystals and ceramics were observed. • Mechanisms of upconversion luminescence in these materials were investigated.

  3. Shift-excitation Raman difference spectroscopy-difference deconvolution method for the luminescence background rejection from Raman spectra of solid samples.

    Science.gov (United States)

    Osticioli, Iacopo; Zoppi, Angela; Castellucci, Emilio Mario

    2007-08-01

    The feasibility of the shift-excitation Raman difference spectroscopy-difference deconvolution (SERDS-DDM) method for fluorescence suppression from Raman spectra of solid samples is discussed. For SERDS measurements a tunable diode laser source with an emission band centered at 684 nm is coupled to a conventional micro-Raman apparatus and a monochromator device is used for checking the excitation frequency stability. The shifted Raman spectra are then mathematically treated and a deconvolution procedure is used to reconstruct the Raman spectrum devoid of fluorescence. Two different cases are presented. In the first one, fluorescence is intrinsic to the sample and the Raman spectrum of cinnabar pigment is finally reconstructed. In the second, the presence of an external luminescence background in the spectrum of a pure sulfur crystal is considered. The SERDS-DDM reconstructed spectra are compared with spectra obtained via multi-point baseline subtraction and a significant improvement in the detection of weak bands is demonstrated. Practical insights for the application of this method are presented as well.

  4. Enhancing the upconversion luminescence and photothermal conversion properties of ∼800nm excitable core/shell nanoparticles by dye molecule sensitization.

    Science.gov (United States)

    Shao, Qiyue; Li, Xiaosong; Hua, Peiyi; Zhang, Gongtuo; Dong, Yan; Jiang, Jianqing

    2017-01-15

    Upconversion nanoparticles capable of strongly absorbing photons in a wide spectral range are highly desired for practical applications. In this work, IR-806 dye was used to increase the light absorptivity of Nd3+/Yb3+/Er3+ tri-doped core/shell nanoparticles and then to enhance their upconversion luminescence under ∼800nm excitation. The IR-806 dye exhibited more efficient energy transfer to Nd3+ ions than to Yb3+ ions for subsequent upconversion emission due to the increased spectral overlap between the dye emission and Nd3+ absorption. The influence of the Nd3+ concentration in the shell and the dye/nanoparticle ratio on the dye-sensitization effect was also investigated. A maximum 28-fold overall enhancement in the emission intensity was achieved for NaYF4:Yb3+/Er3+@NaYF4:Yb3+/Nd3+ core/shell nanoparticles using dye sensitization. The dye-sensitized NaYF4:Yb3+/Er3+@NaYF4:Yb3+/Nd3+ core/shell nanoparticles also exhibited increased photothermal conversion capabilities and excellent temperature sensing properties, enabling their potential application in photothermal nanoheaters with real-time temperature monitoring under 808nm single beam excitation. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Exploring excited-state tunability in luminescent tris-cyclometalated platinum(IV) complexes: synthesis of heteroleptic derivatives and computational calculations.

    Science.gov (United States)

    Juliá, Fabio; Aullón, Gabriel; Bautista, Delia; González-Herrero, Pablo

    2014-12-22

    The synthesis, structure, electrochemistry, and photophysical properties of a series of heteroleptic tris- cyclometalated Pt(IV) complexes are reported. The complexes mer-[Pt(C^N)2 (C'^N')]OTf, with C^N=C-deprotonated 2-(2,4-difluorophenyl)pyridine (dfppy) or 2-phenylpyridine (ppy), and C'^N'=C-deprotonated 2-(2-thienyl)pyridine (thpy) or 1-phenylisoquinoline (piq), were obtained by reacting bis- cyclometalated precursors [Pt(C^N)2 Cl2] with AgOTf (2 equiv) and an excess of the N'^C'H pro-ligand. The complex mer-[Pt(dfppy)2 (ppy)]OTf was obtained analogously and photoisomerized to its fac counterpart. The new complexes display long-lived luminescence at room temperature in the blue to orange color range. The emitting states involve electronic transitions almost exclusively localized on the ligand with the lowest π-π* energy gap and have very little metal character. DFT and time-dependent DFT (TD-DFT) calculations on mer-[Pt(ppy)2 (C'^N')](+) (C'^N'=thpy, piq) and mer/fac-[Pt(ppy)3](+) support this assignment and provide a basis for the understanding of the luminescence of tris-cyclometalated Pt(IV) complexes. Excited states of LMCT character may become thermally accessible from the emitting state in the mer isomers containing dfppy or ppy as chromophoric ligands, leading to strong nonradiative deactivation. This effect does not operate in the fac isomers or the mer complexes containing thpy or piq, for which nonradiative deactivation originates mainly from vibrational coupling to the ground state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Lanthanide Enhanced Luminescence (LEL) with One and Two Photon Excitation of Quantum Dyes(copyright) Lanthanide(III)-Macrocycles

    National Research Council Canada - National Science Library

    Leif, Robert C; Becker, Margie C; Bromm Jr., Al; Chen, Nanguang; Cowan, Ann E; Vallarino, Lidia M; Yang, Sean; Zucker, Robert M

    2004-01-01

    .... Preliminary studies indicate that cells stained with the europium Quantum Dye can be observed both by conventional UV laser excitation and by infrared two-photon confocal microscopy. An enhancer has been found that enables the observation of simultaneous emissions from both the europium and terbium Quantum Dyes.

  7. Comparison of luminescence spectra of natural spodumene under KrCl laser and e-beam excitation

    Energy Technology Data Exchange (ETDEWEB)

    Lipatov, E.I. [High Current Electronics Institute SB RAS, 2/3, Akademichesky Avenue, Tomsk 634055 (Russian Federation)]. E-mail: lipatov@loi.hcei.tsc.ru; Orlovskii, V.M. [High Current Electronics Institute SB RAS, 2/3, Akademichesky Avenue, Tomsk 634055 (Russian Federation); Tarasenko, V.F. [High Current Electronics Institute SB RAS, 2/3, Akademichesky Avenue, Tomsk 634055 (Russian Federation); Solomonov, V.I. [Institute of Electrophysics UB RAS, 106, Amundsen Street, Ekaterinburg (Russian Federation)

    2007-10-15

    Spectral characteristics of pulsed photoluminescence (PL) and pulsed cathodoluminescence (PCL) of a natural spodumene were investigated. PL was excited by laser radiation at 222 nm with pulse duration of 10 ns at FWHM. PCL was excited by electron beams with pulse duration from 0.1 up to 4 ns and with current densities of 40-200 A/cm{sup 2}. There was a dominant broad band at 600 nm due to the manganese impurity in PCL spectra. But in PL spectra, the orange band had the intensity comparable with intensities of intrinsic defect bands. At sample cooling by liquid nitrogen, the intensity of orange band in the PCL spectrum increased by two times and the short-wave shoulder of the band reduced.

  8. Luminescence property and lowest excited singlet state level of various carotenes; Shuju no karochinrui no hako tokusei to saitei reiki -juko jotai jun'i

    Energy Technology Data Exchange (ETDEWEB)

    Ito, T. [Miyagi Midical Univ., Miyagi (Japan)

    2000-01-01

    Specification of the lowest excited singlet state (S{sub l}) of the butadiene which is the simplest {pi} electron conjugated system molecule has not sufficiently clarified at present. Recently, Andersson et al. found the weak light emission which was considered to be the S{sub 1} fluorescence in a near infrared region in a room temperature solution of {beta}- carotene (n=11), and specified the S{sub 1} level in 14,200{+-}500cm {sup -1}. And, Fujii et al. reported the S{sub 1} fluorescence of spheroidine (n=10). In very recent, Christensen et al. measured the comparatively clear fluorescence spectrum of carotenes n=5 to 11 separated by HPLC in EPA glass at 77K, and systematically examined the unique luminescence property observed in polyene. Christensen et al. issued the warning for the rough conventional method that the S{sub 1} level was estimated from the S{sub 1} fluorescence lifetime of the polyene molecule using the comprehensive energy gap law, because the ratio of quantum yield of the S{sub 1} and S{sub 2} fluorescence is different by the substituent type of the polyene end even if n is same. (NEDO)

  9. Colour centres formation in CaF{sub 2} single crystals by {gamma}-rays and reactor neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Izerrouken, M., E-mail: izerrouken@yahoo.co [Centre de Recherche Nucleaire de Draria (CRND), BP.43, Sebbala, Draria, Algiers (Algeria); Guerbous, L. [Centre de Recherche Nucleaire d' Alger (CRNA), 2 Bd Frantz Fanon, BP 399, Alger gare (Algeria); Meftah, A. [LRPCSI, Universite 20 Aout 55, Skikda, route d' El-Hadaik, BP. 26, 21000 Skikda (Algeria)

    2010-09-21

    The induced colour in single crystals of calcium fluoride irradiated with {gamma}-rays and reactor neutrons have been investigated by optical measurements (absorption and photoluminescence). The optical absorption spectrum increases slightly by increasing {gamma}-rays dose up to 10{sup 6} Gy and absorption bands centred at about 225, 260, 340, 396 and 580 nm are observed. At higher doses, in the case of reactor neutrons irradiation, the absorption spectrum shows a large absorption band centred at about 415 nm and shoulders at 340 nm and 550 nm. This indicates that the absorption bands at 225, 260 and 580 nm are probably saturated at higher doses. Whereas, the band at 396 nm presents both saturation and linearly increasing behaviour. On heating a sample after irradiation, the absorption bands at 225, 260 and 580 nm disappear at 140 {sup o}C, and the 396 nm absorption band disappears above 250 {sup o}C. Photoluminescence excited with 325 nm photon shows an emission band centred at about 420 nm in the non-irradiated sample. The intensity of such band deceases after irradiation.

  10. Optical Biomedical Diagnostics: Sensors with Optical Response Based on Two-Photon Excited Luminescent Dyes for Biomolecules Detection

    Directory of Open Access Journals (Sweden)

    V. M. Yashchuk

    2008-01-01

    Full Text Available The spectral properties of novel styryl dyes developed for the biomacromolecules (such as DNA detection and imaging were investigated. The energy structures of dye molecules were examined. The spectral data prove that dyes aggregate and interact with DNA. The essential increase of the fluorescence intensity of dyes in the presence of DNA was observed. The photostability and phototoxic influence on the DNA of several styryl dyes were studied by analyzing absorption, fluorescence, and phosphorescence spectra of these dyes and dye-DNA systems. Changes of the optical density value of dye-DNA solutions caused by the irradiation were fixed in the DNA and dye absorption wavelength regions. Fluorescence emission of dye-DNA complexes upon two-photon excitation at wavelength 1064 nm with the 20-nanosecond pulsed YAG:Nd3+ laser and at 840 nm with the 90 famtosecond pulsed Ti:sapphire laser was registered. The values of two-photon absorption cross-sections of dye-DNA complexes were evaluated.

  11. Excited states

    CERN Document Server

    Lim, Edward C

    1974-01-01

    Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

  12. Luminescence of Ce.sup.3+./sup.- and Eu.sup.2+./sup.- doped silica glassesunder UV and X-ray excitation

    Czech Academy of Sciences Publication Activity Database

    Chewpraditkul, W.; Shen, Y.; Chen, D.; Nikl, Martin; Beitlerová, Alena

    2013-01-01

    Roč. 15, 1-2 (2013), s. 94-98 ISSN 1454-4164 R&D Projects: GA MŠk LH12185 Institutional support: RVO:68378271 Keywords : Ce 3+ * Eu 2+ * luminescence * photoluminescence decay * porous materials * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.563, year: 2013

  13. Upconversion luminescence of β-NaYF4: Yb3+, Er3+@β-NaYF4 core/shell nanoparticles: Excitation power density and surface dependence

    NARCIS (Netherlands)

    Wang, Y.; Tu, L.; Zhao, J.; Sun, Y.; Kong, X.; Zhang, H.

    2009-01-01

    Coating a homogeneous layer outside the core nanoparticles has become a common method to improve the optical properties of nanoparticles. For rare earth ion-doped nanoparticles, although the homogeneous coating is found to enhance the upconversion luminescence, a large deviation in the reported

  14. Luminescence Instrumentation

    DEFF Research Database (Denmark)

    Jain, Mayank; Bøtter-Jensen, Lars

    2014-01-01

    This chapter gives an introduction to instrumentation for stimulated luminescence studies, with special focus on luminescence dating using the natural dosimeters, quartz and feldspars. The chapter covers basic concepts in luminescence detection, and thermal and optical stimulation, and reference...... irradiation. It then briefly describes development of spectrometers in dating applications, and finally gives an overview of recent development in the field directly linked to novel instrumentation. Contents of Paper...

  15. luminescence properties

    Indian Academy of Sciences (India)

    )-based phosphors which were synthesized by the conventional solid-state reaction method, their crystal structures and luminescence properties were investigated. X-ray diffraction patterns (XRD) showed that phosphors sintered at 1000 ◦C for ...

  16. Luminescence decay of S Zn::Ag and O Zn:Ga scintillation detectors excited by a pulsed laser; Evolucion temporal de la luminiscencia producida por un laser pulsado de los detectores de centello SZn:Ag y OZn:Ga

    Energy Technology Data Exchange (ETDEWEB)

    Romero, L.; Campos, J.

    1981-07-01

    In the present work a high sensitivity experimental set up for luminescence decay measurements in the 1 0 {sup -}1 sec range has been developed. As an application, luminescence light decay In S Zn:Ag and 0Zn:Ga after excitation by a pulsed N{sub 2} laser has been measured. In SZnrAg, measurements of total light decay was compared with donor acceptor pairs theory. In both substances, spectral evolution in the first 15 sec was investigated. (Author) 4 refs.

  17. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  18. Elimination of photon quenching by a transition layer to fabricate a quenching-shield sandwich structure for 800 nm excited upconversion luminescence of Nd3+-sensitized nanoparticles.

    Science.gov (United States)

    Zhong, Yeteng; Tian, Gan; Gu, Zhanjun; Yang, Yijun; Gu, Lin; Zhao, Yuliang; Ma, Ying; Yao, Jiannian

    2014-05-01

    Nd3+-sensitized quenching-shield sandwich-structured upconversion nanoparticles are reported, which exhibit highly efficient upconversion photoluminescence under excitation by an 800 nm continuous-wave laser. The transition-layer structure is essential to bridge energy transfer from the sensitizer to the activator and simultaneously block energy back-transfer from the activator to the sensitizer. These 800 nm-excited upconversion nanoparticles are a key step toward the development of upconversion nanophosphors for biological applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Data processing correction of the irising effect of a fast-gating intensified charge-coupled device on laser-pulse-excited luminescence spectra.

    Science.gov (United States)

    Ondic, L; Dohnalová, K; Pelant, I; Zídek, K; de Boer, W D A M

    2010-06-01

    Intensified charge-coupled devices (ICCDs) comprise the advantages of both fast gating detectors and spectrally broad CCDs into one device that enables temporally and spectrally resolved measurements with a few nanosecond resolution. Gating of the measured signal occurs in the image intensifier tube, where a high voltage is applied between the detector photocathode and a microchannel plate electron multiplier. An issue arises in time-resolved luminescence spectroscopy when signal onset characterization is required. In this case, the transient gate closing process that causes the detected signal always arises in the middle of the ICCD chip regardless of the spectral detection window--the so-called irising effect. We demonstrate that in case when the detection gate width is comparable to the opening/closing time and the gate is pretriggered with respect to the signal onset, the irising effect causes the obtained data to be strongly distorted. At the same time, we propose a software procedure that leads to the spectral correction of the irising effect and demonstrate its validity on the distorted data.

  20. Electronic structure of InAs/GaAs self-assembled quantum dots studied by high-excitation luminescence in magnetic fields up to 73 T

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, D.; Raymond, S.; Studenikin, S.; Babinski, A.; Leotin, J.; Frings, P.; Potemski, M.; Sachrajda, A

    2004-04-30

    We report on high-excitation photoluminescence (PL) measurements of an ensemble of InAs/GaAs self-assembled quantum dots with large inter-shell spacing (75 meV) in magnetic fields up to 73 T. The PL spectra show a complex picture of levels splitting and crossings. A simple two-band single-particle model provides a good approximation to explain the observed magneto-PL spectra.

  1. Organic scintillators with long luminescent lifetimes for radiotherapy dosimetry

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Lindvold, Lars René; Andersen, Claus Erik

    2011-01-01

    of experiments performed using two organic scintillators, one commercially available and one custom made. The luminescent lifetimes of the scintillators have been measured using i) optical excitation by pulsed UV light, and ii) irradiative excitation using high-energy X-rays from a linac. A luminescent lifetime......Organic scintillators with long luminescent lifetimes can theoretically be used to temporally filter out radiation-induced luminescence and Cerenkov light (the so-called stem signal) when used as fibre-coupled radiotherapy dosimeters. Since the medical linear accelerators (linacs1) used...

  2. Computational studies on the excited states of luminescent platinum(II) alkynyl systems of tridentate pincer ligands in radiative and nonradiative processes.

    Science.gov (United States)

    Lam, Wai Han; Lam, Elizabeth Suk-Hang; Yam, Vivian Wing-Wah

    2013-10-09

    Platinum(II) alkynyl complexes of various tridentate pincer ligands, [Pt(trpy)(C≡CR)](+) (trpy = 2,2':6',2″-terpyridine), [Pt(R'-bzimpy)(C≡CR)](+) (R'-bzimpy = 2,6-bis(N-alkylbenzimidazol-2'-yl)pyridine and R' = alkyl), [Pt(R'-bzimb)(C≡CR)] (R'-bzimb = 1,3-bis(N-alkylbenzimidazol-2'-yl)benzene and R' = C4H9), have been found to possess rich photophysical properties. The emission in dilute solutions of [Pt(trpy)(C≡CR)](+) originated from a triplet alkynyl-to-tridentate pincer ligand-to-ligand charge transfer (LLCT) excited state, with mixing of a platinum-to-tridentate pincer ligand metal-to-ligand charge transfer (MLCT) excited state, while that of [Pt(R'-bzimb)(C≡CR)] originated from a triplet excited state of intraligand (IL) character of the tridentate ligand mixed with a platinum-to-tridentate ligand MLCT character. Interestingly, both emissions were observed in [Pt(R'-bzimpy)(C≡CR)](+) in some cases. In addition, [Pt(R'-bzimb)(C≡CR)] displayed a photoluminescence quantum yield higher than that of [Pt(R'-bzimpy)(C≡CR)](+). Computational studies have been performed on the representative complexes [Pt(trpy)(C≡CPh)](+) (1), [Pt(R'-bzimpy)(C≡CPh)](+) (2), and [Pt(R'-bzimb)(C≡CPh)] (3), where R' = CH3 and Ph = C6H5, to provide an in-depth understanding of the nature of their emissive origin as well as the radiative and nonradiative processes. In particular, the factors governing the ordering of the triplet excited states and radiative decay rate constants of the emissive state ((3)ES) have been examined. The potential energy profiles for the deactivation process from the (3)ES via triplet metal-centered ((3)MC) states have also been explored. This work reveals for the first time the potential energy profiles for the thermal deactivation pathway of square planar platinum(II) complexes.

  3. Luminescent characteristics of UV excited Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: Pr{sup 3+} reddish-orange phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R., E-mail: prb.mgu@gmail.com

    2016-02-15

    Pr{sup 3+} doped Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3} phosphors were synthesised by solid state reaction process. The structure, surface morphology and photoluminescence of the prepared phosphors were analysed using XRD, SEM and photoluminescence spectroscopy respectively. The XRD pattern confirmed orthorhombic perovskite structure of the Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor shows the samples can be effectively excited with UV light at 336 nm and exhibit a strong reddish-orange emission at 611 nm. Concentration dependence of emission intensity shows concentration quenching effect on increasing Pr{sup 3+} concentration after x = 0.1 because of dipole–dipole interaction. Using Blasse's formula, critical distance for energy transfer was calculated. The CIE co-ordinates, CCT, colour purity and luminescence decay of the prepared phosphors were also calculated. These results offer the prepared phosphor as a suitable candidate for various photonic applications. - Highlights: • Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from {sup 3}P{sub J} levels of Pr{sup 3+} were absent due to the presence of IVCT band. • Concentration quenching due to dipole–dipole interaction was observed. • For x = 0.1, sample shows a maximum emission intensity with 91.7% colour purity.

  4. Micro-modulated luminescence tomography

    CERN Document Server

    Cong, Wenxiang; Wang, Chao; Wang, Ge

    2013-01-01

    Imaging depth of optical microscopy has been fundamentally limited to millimeter or sub-millimeter due to light scattering. X-ray microscopy can resolve spatial details of few microns deeply inside a sample but the contrast resolution is still inadequate to depict heterogeneous features at cellular or sub-cellular levels. To enhance and enrich biological contrast at large imaging depth, various nanoparticles are introduced and become essential to basic research and molecular medicine. Nanoparticles can be functionalized as imaging probes, similar to fluorescent and bioluminescent proteins. LiGa5O8:Cr3+ nanoparticles were recently synthesized to facilitate luminescence energy storage with x-ray pre-excitation and the subsequently stimulated luminescence emission by visible/near-infrared (NIR) light. In this paper, we suggest a micro-modulated luminescence tomography (MLT) approach to quantify a nanophosphor distribution in a thick biological sample with high resolution. Our numerical simulation studies demonst...

  5. Vacuum ultraviolet excited luminescence properties of sol–gel derived GdP{sub 5}O{sub 14}:Eu{sup 3+} powders

    Energy Technology Data Exchange (ETDEWEB)

    Mbarek, Aïcha [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Laboratoire de Chimie Industrielle, Ecole Nationale d' Ingénieurs de Sfax, Université de Sfax, BP W 3038, Sfax (Tunisia); Chadeyron, Geneviève, E-mail: genevieve.chadeyron@ensccf.fr [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Boyer, Damien [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Avignant, Daniel [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); Fourati, Mohieddine [Laboratoire de Chimie Industrielle, Ecole Nationale d' Ingénieurs de Sfax, Université de Sfax, BP W 3038, Sfax (Tunisia); Zambon, Daniel [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 CLERMONT-FERRAND (France); and others

    2014-01-15

    Sol–gel route has successfully been used to synthesize pure and Eu{sup 3+} doped polycrystalline samples of the GdP{sub 5}O{sub 14} pentaphosphates. The as-prepared samples have structurally been characterized using X-ray diffraction. Optical properties in the vacuum ultraviolet (VUV) of Eu{sup 3+} activated GdP{sub 5}O{sub 14} samples prepared either by sol–gel process or solid-state reaction were investigated at room temperature for comparison. In this GdP{sub 5}O{sub 14} host matrix the P{sub 5}O{sub 14} ultraphosphate groups were proved to exhibit an efficient absorption in the VUV range. The excitation spectra recorded in the VUV-UV spectral region from 120 nm to 350 nm have revealed the presence of Gd{sup 3+} 4f–5d interconfiguration transitions, Gd{sup 3+}–O{sup 2−} and Eu{sup 3+}–O{sup 2−} charge transfer states(CTS)in addition to intraconfiguration transitions of Gd{sup 3+} ions.Furthermore the Gd{sup 3+}→Eu{sup 3+} energy transfer process was investigated and discussed in the framework of the multiphonon relaxation process. Besides, the GdP{sub 5}O{sub 14}:Eu{sup 3+} phosphor led to a strong red emission under 147/172 nm excitation, so that it can be considered as a promising red phosphor for mercury-free lamps and plasma display panels applications. -- Highlights: • Lanthanide pentaphosphates were synthesized by the sol–gel process. • A broad absorption was evidenced in the VUV range for GdP{sub 5}O{sub 14}:Eu{sup 3+}. • An efficient energy transfer was proved from pentaphosphate lattice to Eu{sup 3+} ions.

  6. Luminescence basic concepts, applications and instrumentation

    CERN Document Server

    Virk, Hardev Singh

    2014-01-01

    The word luminescence was first used by a German physicist, Eilhardt Wiedemann, in 1888. He also classified luminescence into six kinds according to the method of excitation. No better basis of classification is available today. He recognized photoluminescence, thermoluminescence, electroluminescence, crystalloluminescence, triboluminescence, and chemiluminescence. The designations are obvious, characterized by the prefix. This Volume consists of 9 Chapters, including 8 Review Papers and one Case Study. The first two papers are based on OLEDs. Organic light emitting diodes (OLEDs) have been th

  7. Luminescence efficiency during ion implantation of sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Alghamdi, A.; Townsend, P.D. (Sussex Univ., Brighton (UK). School of Mathematical and Physical Sciences)

    1990-01-01

    Luminescence signals produced during ion implantation of sapphire are related to the F,F{sup +} and F{sub 2} defect centres. However, the efficiency of light production changes with ion beam dose, the rate of energy deposition and radiation damage, hence the signals are not proportional to the defect concentrations. Data are presented which suggest that the light is primarily produced by electronic excitation. Luminescence efficiency within the region of nuclear collisions is very low. It is not possible to determine the energy dependence of the luminescence intensity, as a function of ion energy, by energy variations within a single target crystal. (author).

  8. Gold nanoantenna resonance diagnostics via transversal particle plasmon luminescence.

    Science.gov (United States)

    Wissert, Matthias D; Moosmann, Carola; Ilin, Konstantin S; Siegel, Michael; Lemmer, Uli; Eisler, Hans-Jürgen

    2011-02-14

    We perform two-photon excitation confocal experiments on coupled gold nanoantennas and observe time-integrated luminescence spectra that match plasmonic mode emission in the far-field. We show that the transversal particle plasmon mode can be excited, using excitation light that is cross-polarized with respect to the gold luminescence signal and therefore oriented along the long axis of the dipole gold antenna. We provide evidence for losses in polarization information from the excitation channel to the luminescence response due to the nature of the energy and momentum transfer. Finally, we map out the two-photon induced luminescence intensity profile for a fixed excitation wavelength λ and varying antenna arm length L.

  9. Synthesis, structural characterization and VUV excited luminescence properties of LixNa(1-x)Sm(PO3)4 polyphosphates

    Science.gov (United States)

    Sebai, S.; Hammami, S.; Megriche, A.; Zambon, D.; Mahiou, R.

    2016-12-01

    Stoichiometric phosphors Li(x)Na(1-x)Sm(PO3)4(x = 0, 0.5, 1) were prepared in the solid state and were characterized at room temperature using X-ray diffraction, infrared and Raman spectroscopy. The obtained LiSm(PO3)4 and NaSm(PO3)4 polycrystalline samples are single-phased and have centrosymmetric monoclinic structure. The observed results show the presence of characteristic bands due to (PO2)- terminal and P-O-P bridging groups. However, the Li0.5Na0.5Sm(PO3)4 material seems to be a mixture of the Li and Na homologues. The VUV excitation and emission spectra of as-synthesized compounds were measured. It was found that the Sm3+ ions show an orange-red emission which corresponds to the group transitions 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, 11/2), with the strongest transition (4G5/2 → 6H7/2) peaking at around 597 nm. The decay curves were pure exponential. The derived time constants are comprise between 14 μs and 31 μs, the lowest value is for NaSm(PO3)4. The decays were modeled in the frame of fast diffusion model with a rough estimation of fast cross-relaxation mechanism which returns a cross-relaxation rate of 3-7 × 104 s-1 and diffusion constant of 1-2 × 10-9 cm2 s-1.

  10. Luminescence performance of Eu 3-doped lead-free zinc phosphate ...

    Indian Academy of Sciences (India)

    Luminescence performance of Eu$^{3+}-doped lead-free zinc phosphate glasses for red emission. Y C RATNAKARAM V ... These glasses were characterized by several spectroscopic techniques at room temperature. Allthe glasses showed relatively broad fluorescence excitation and luminescence spectra. Luminescence ...

  11. Persistent luminescence nanothermometers

    Science.gov (United States)

    Martín Rodríguez, Emma; López-Peña, Gabriel; Montes, Eduardo; Lifante, Ginés; García Solé, José; Jaque, Daniel; Diaz-Torres, Luis Armando; Salas, Pedro

    2017-08-01

    Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20-60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.

  12. Understanding the influence of nanoenvironment on luminescence ...

    Indian Academy of Sciences (India)

    The role of the rare-earth ion concentration, crystal size and crystal phase on the up- and downconversion emission of rare-earth ions in oxide nanocrystals and their underlying mechanisms are discussed. It is also found that the luminescence lifetime of the excited state rare-earth ions is sensitive to the particle crystalline ...

  13. Feldspar, Infrared Stimulated Luminescence

    DEFF Research Database (Denmark)

    Jain, Mayank

    2014-01-01

    This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars.......This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars....

  14. Monitoring Delamination of Thermal Barrier Coatings by Near-Infrared and Upconversion Luminescence Imaging

    Science.gov (United States)

    Eldridge, J. I.; Martin, R. E.; Singh, Jogender; Wolfe, Doug E.

    2008-01-01

    Previous work has demonstrated that TBC delamination can be monitored by incorporating a thin luminescent sublayer that produces greatly increased luminescence intensity from delaminated regions of the TBC. Initial efforts utilized visible-wavelength luminescence from either europium or erbium doped sublayers. This approach exhibited good sensitivity to delamination of electron-beam physical-vapor-deposited (EB-PVD) TBCs, but limited sensitivity to delamination of the more highly scattering plasma-sprayed TBCs due to stronger optical scattering and to interference by luminescence from rare-earth impurities. These difficulties have now been overcome by new strategies employing near-infrared (NIR) and upconversion luminescence imaging. NIR luminescence at 1550 nm was produced in an erbium plus ytterbium co-doped yttria-stabilized zirconia (YSZ) luminescent sublayer using 980-nm excitation. Compared to visible-wavelength luminescence, these NIR emission and excitation wavelengths are much more weakly scattered by the TBC and therefore show much improved depth-probing capabilities. In addition, two-photon upconversion luminescence excitation at 980 nm wavelength produces luminescence emission at 562 nm with near-zero fluorescence background and exceptional contrast for delamination indication. The ability to detect TBC delamination produced by Rockwell indentation and by furnace cycling is demonstrated for both EB-PVD and plasma-sprayed TBCs. The relative strengths of the NIR and upconversion luminescence methods for monitoring TBC delamination are discussed.

  15. Probing luminescence centers in Na rich feldspar

    DEFF Research Database (Denmark)

    Prasad, Amit Kumar; Lapp, Torben; Kook, Myung Ho

    2016-01-01

    In contrast to the detailed investigations on the dosimetric electron trap in feldspar only little has been done to understand the luminescence centers. We use a comparison of multiple spectroscopic techniques, site selective photoluminescence spectroscopy and time resolved measurements to further...... our understanding of the luminescence mechanisms and recombination sites, in a sample of Na rich plagioclase feldspar (oligoclase). Both the UV and violet–blue emissions show resonant excitations arising from a distribution of energy levels. We propose, contrary to the general understanding......, that the green emission may not arise from Mn2+ in our sample and that photoionisation of this centre may be possible by excitation to the band tail states. The deep red emission is tied to the Fe3+, and the exponential rise in the UV excitation efficiency of this centre is discussed in the context of the band...

  16. The sensitized luminescence of manganese-activated calcite

    Science.gov (United States)

    Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

    1947-01-01

    Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

  17. Magnetic-luminescent spherical particles synthesized by ultrasonic spray pyrolysis

    Science.gov (United States)

    Michel, Norma L.; Flores, Dora L.; Hirata, Gustavo A.

    2015-07-01

    The combination of magnetic and luminescent properties in a single particle system, opens-up a wide range of potential applications in biotechnology and biomedicine. In this work, we performed the synthesis of magnetic-luminescent Gd2O3:Eu3+@Fe2O3 particles by ultrasonic spray pyrolysis performed in a tubular furnace. In order to achieve the composite formation, commercial superparamagnetic Fe3O4 nanoparticles were coated with a luminescent Eu3+-doped Gd2O3 shell in a low-cost one-step process. The spray pyrolysis method yields deagglomerated spherical shape magneto/luminescent particles. The photoluminescence spectra under UV excitation (λExc = 265 nm) of the magnetic Gd2O3:Eu3+@Fe2O3 compound showed the characteristic red emission of Eu3+ (λEm = 612 nm). This magneto/luminescent system will find applications in biomedicine and biotechnology.

  18. Luminescence spectra and kinetics of disordered solid solutions

    DEFF Research Database (Denmark)

    Klochikhin, A.; Reznitsky, A.; Permogorov, S.

    1999-01-01

    for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated ''radiative" states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long......We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized...... only a relatively small group of ''radiative" states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the ''radiative'' localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found...

  19. Doping-induced luminescence in polyacetylene

    Science.gov (United States)

    Kürti, J.; Kuzmany, H.

    1988-09-01

    In situ measurements of the emission of secondary radiation from trans-polyacetylene during electrochemical p and n doping are reported. The luminescencelike emission was observed to be reversible with the doping and undoping process, and it was independent with respect to three different electrolyte systems: Li+ClO-4 in sulfolane, Li+ClO-4 in propylenecarbonate, and Li+BF-4 in propylenecarbonate, which proves its origin from the polymer backbone. No reversible luminescence occurs during n doping. The intensity of the luminescence spectrum has a maximum for the laser excitation in the yellow-green spectral region. The maximum position of the luminescence spectrum shifts by about 3000 cm-1 for a shift of the excitation energy of 7000 cm-1. The observed luminescence phenomena are explained by the polaron-doping mechanism in the disordered part of the sample and photoselective resonance process. A quantitative description is presented by calculating the energy for polaron levels by the Hückel method including geometry relaxation.

  20. Luminescent beam stop

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Diane; Morton, Simon A.

    2017-10-25

    This disclosure provides systems, methods, and apparatus related to beam stops. In one aspect, a device comprises a luminescent material, a beam stop plate, and an optical fiber. The luminescent material is a parallelepiped having a first side and a second side that are squares and having a third side that is a rectangle or a square. The first side and the second side are perpendicular to the third side. The beam stop plate is attached to the first side of the luminescent material. The optical fiber has a first end and a second end, with the first end of the optical fiber attached to the third side of the luminescent material.

  1. Applications of quantum dots with upconverting luminescence in bioimaging.

    Science.gov (United States)

    Chen, Yunyun; Liang, Hong

    2014-06-05

    Quantum dots (QDs) have attracted great attention in recent years due to their promising applications in bioimaging. Compared with traditional ultraviolet excitation of QDs, near-infrared laser (NIR) excitation has many advantages, such as being less harmful, little blinking effects, zero autofluorescence and deep penetration in tissue. Composing QDs with upconverting properties is promising to enable NIR excitation. This article provides a review of QDs with upconverting luminescence and their applications in bioimaging. Based on the mechanisms of luminescence, discussion will be divided into four groups: nanoheterostructures/mixtures of QDs and upconverting nanoparticles, graphene quantum dots, lanthanide-doped QDs, and double QDs. The content includes synthetic routes, upconverting luminescence properties, and their applications in bioimaging. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Luminescent determination of ascorbic acid in dietary supplements

    Directory of Open Access Journals (Sweden)

    E. Malinka

    2017-06-01

    Full Text Available The article presents the results of the ascorbic acid (AA determination with using a complex of an Tb (III ion with ciprofloxacin (CF as a lanthanide luminescent marker. The luminescent properties of the Tb (III-CF complex in the presence of AA were studied. The excitation and luminescence spectra, triplet level of ligand, the kinetics of the luminescence decay of the Tb(III-CF complex in the presence of AA were analyzed. The excitation spectrum of the Tb (III- CF complex has broad bands with maxima at 302 and 355 nm that corresponding to the n→π* electronic transition in the absorption spectrum of ligand. The luminesce spectra demonstrate the emission transitions arising from 5D4 energy level to 7Fj multiplet ground state. The luminescence of the Tb(III-CF complex was found to be quenched by AA. It was established that the lifetime of the excited 5D4 state of the Tb (III ion decreases with AA concentration increasing up to 0,25 mg/сm3. Luminescence quenching of the Tb (III-CF complex by AA follows the Stern-Volmer relationship of AA. The Stern-Volmer constant K is 2478 dm3/mol. The biomolecular quenching rate constant kq is 1,25∙107 dm3/mol. The effect of luminescence quenching of the Tb (III-CF complex was used to developing the procedure for determining of AA in the dietetic additives «Asvitol» and «Ascorbic acid». The linear calibration plot for AA was obtained over the concentration range of 0,02 to 0,25 mg/сm3.

  3. Red luminescence from hydrothermally synthesized Eu-doped ZnO ...

    Indian Academy of Sciences (India)

    Photoluminescence studies show that these nanoparticles exhibit a sharp red luminescence due to the intra-4 transitions of Eu3+ ions at an excitation of 397 nm and 466 nm. Luminescence quenching is observed in the nanoparticles as the Eu-dopant concentration increases. Incorporation of Eu in the nanoparticles was ...

  4. Lanthanide luminescence quenching as a detection method in ion chromatography. Chromate in surface and drinking water

    NARCIS (Netherlands)

    SCHREURS, M; Somsen, G. W.; Gooijer, C.; Velthorst, N. H.; Frei, R W

    1989-01-01

    Dynamic quenching of Eu(IIl) and TB(III) luminescence by inorganic anions as a detection method in ion chromatography was investigated. To obtain a high luminescence intensity lanthanide(III) complexes are formed with ligands which make indirect excitation of the ions possible. Only a few anions

  5. Radiation induced luminescence processes in c-BN

    DEFF Research Database (Denmark)

    Trinkler, L.; Berzina, B.; Benabdesselam, M.

    2004-01-01

    Spectral properties of cubic boron nitride have been studied using methods of photoluminescence (PL), X-ray excited luminescence (XL), thermoluminescence (TL) and optically stimulated luminescence. It is found that emission of cubic boron nitride is presented by 4 subbands, their relative yield...... is determined by the excitation type: blue, green (dominant) and red bands are observed in PL, ultraviolet, blue (dominant), green and red bands-in XL. Three thermal peaks are found in TL curves in the 0-700degreesC temperature range, their presence and intensity depend on radiation type used. A tentative...

  6. Violet-green excitation for NIR luminescence of Yb3+ ions in Bi2O3-B2O3-SiO2-Ga2O3 glasses.

    Science.gov (United States)

    Li, Weiwei; Cheng, Jimeng; Zhao, Guoying; Chen, Wei; Hu, Lili; Guzik, Malgorzata; Boulon, Georges

    2014-04-21

    60Bi(2)O(3)-20B(2)O(3)-10SiO(2)-10Ga(2)O(3) glasses doped with 1-9 mol% Yb(2)O(3) were prepared and investigated mainly on their violet-green excitation for the typical NIR emission of Yb(3+), generally excited in the NIR. Two violet excitation bands at 365 nm and 405 nm are related to Yb(2+) and Bi(3+). 465 nm excitation band and 480 nm absorption band in the blue-green are assigned to Bi(0) metal nanoparticles/grains. Yb-content-dependence of the excitation and absorption means that Bi(0) is the reduced product of Bi(3+), but greatly competed by the redox reaction of Yb(2+) ↔ Yb(3+). It is proved that the violet-green excitations result in the NIR emission of Yb(3+). On the energy transfer, the virtual level of Yb(3+)-Yb(3+) as well as Bi(0) dimers probably plays an important role. An effective and controllable way is suggested to achieve nano-optical applications by Bi(0) metal nanoparticles/grains and Yb(3+).

  7. Luminescence techniques: Instrumentation and methods

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.

    1997-01-01

    This paper describes techniques, instruments and methods used in luminescence dating and environmental dosimetry in many laboratories around the world. These techniques are based on two phenomena - thermally stimulated luminescence and optically stimulated luminescence. The most commonly used...... luminescence stimulation and detection techniques are reviewed and information is given on recent developments in instrument design and on the stale of the art in luminescence measurements and analysis. (C) 1998 Elsevier Science Ltd. All rights reserved....

  8. Quantum lattice fluctuations in a 1-dimensional charge-density-wave material: Luminescence and resonance Raman studies of an MX solid

    Energy Technology Data Exchange (ETDEWEB)

    Long, F.H.; Love, S.P.; Swanson, B.I.

    1993-01-01

    Luminescence spectra, both emission and excitation, and the excitation dependence of the resonance Raman (RR) spectra were measured for a 1-dimensional charge-density-wave solid, [Pt(L)[sub 2]Cl[sub 2

  9. Semiconducting Polymer Nanoparticles with Persistent Near-Infrared Luminescence for In Vivo Optical Imaging.

    Science.gov (United States)

    Palner, Mikael; Pu, Kanyi; Shao, Shirley; Rao, Jianghong

    2015-09-21

    Materials with persistent luminescence are attractive for in vivo optical imaging since they have a long lifetime that allows the separation of excitation of fluorophores and image acquisition for time-delay imaging, thus eliminating tissue autofluorescence associated with fluorescence imaging. Persistently luminescent nanoparticles have previously been fabricated from toxic rare-earth metals. This work reports that nanoparticles made of the conjugated polymer MEH-PPV can generate luminescence persisting for an hour upon single excitation. A near-infrared dye was encapsulated in the conjugated polymer nanoparticle to successfully generate persistent near-infrared luminescence through resonance energy transfer. This new persistent luminescence nanoparticles have been demonstrated for optical imaging applications in living mice. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Vacuum ultraviolet excited luminescence properties of Ca3Gd7(SiO4)5(PO4)O2:Re3+ (Re3+=Tb3+, Dy3+) phosphors

    Science.gov (United States)

    Zhang, Feng; Wang, Yuhua; Huang, Yan; Tao, Ye

    2013-10-01

    A series of Ca3Gd7(SiO4)5(PO4)O2:Re3+ (Re3+=Tb3+, Dy3+) phosphors were synthesized by a solid-state reaction, and their vacuum ultraviolet excitation and emission characteristics were measured. All the excitation spectra show a broad band in the region of 140-210 nm, which can be mainly assigned to the host absorption. For Tb3+-doped sample, the absorption bands at 230 nm and 281 nm are respectively ascribed to the f-d spin-allowed and spin-forbidden transitions of Tb3+. In Dy3+-doped sample, the f-d spin-allowed transitions of Dy3+ and O2-→Dy3+ charge transfer band have not been clearly distinguished probably because of the overlapping with the strong host absorption band. The weak bands at 267 and 288 nm are attributed to be the f-d spin-forbidden transitions of Dy3+. The concentration dependence of the emission intensity upon the excitation at 172 nm indicates that the optimal doping concentrations of Tb3+ and Dy3+ are 11 mol% and 5 mol%, respectively. The optimal Tb3+ and Dy3+-activated samples respectively exhibit yellowish green and white emitting colors due to their characteristic emissions.

  11. Exploring the effect of remote substituents and solution structure on the luminescence of three lanthanide complexes

    Energy Technology Data Exchange (ETDEWEB)

    Tropiano, Manuel; Blackburn, Octavia A.; Tilney, James A.; Hill, Leila R. [Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA (United Kingdom); Just Sørensen, Thomas, E-mail: TJS@chem.ku.dk [Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA (United Kingdom); Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø (Denmark); Faulkner, Stephen, E-mail: stephen.faulkner@chem.ox.ac.uk [Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA (United Kingdom)

    2015-11-15

    Sensitized luminescence from trivalent lanthanide ions relies on an appropriate energy match between the sensitizer’s excited state (triplet or singlet) and the lanthanide excited state manifold, and also an efficient mechanism of energy transfer between the two. Here, the effect of remote substituents on the luminescence properties of a series of related lanthanide complexes has been investigated. The sensitized lanthanide centered emission is not invariably found to occur following excitation of all chromophores in all systems, and it is shown that only the most structurally congested of the systems investigated exhibited pronounced solvatochromism. - Highlights: • Effect of remote substituents and self-assembly on lanthanide luminescence. • Molecular structure rather than chromophore density defines lanthanide sensitization. • Kimura's and Horrocks' approach to determine lanthanide solvation is revisited. • Solvent alters sensitization pathways in multinuclear lanthanide complexes. • Increasing chromophore density may reduce lanthanide luminescence.

  12. Self-trapped exciton and core-valence luminescence in BaF{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Vistovskyy, V. V., E-mail: vistvv@gmail.com; Zhyshkovych, A. V.; Chornodolskyy, Ya. M.; Voloshinovskii, A. S. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine); Myagkota, O. S. [Lviv Polytechnic National University, 12S. Bandera, 79013 Lviv (Ukraine); Gloskovskii, A. [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany); Gektin, A. V. [Institute for Scintillation Materials, NAS of Ukraine 60 Lenina Ave, 61001 Kharkiv (Ukraine); Vasil' ev, A. N. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Rodnyi, P. A. [Saint-Petersburg State Polytechnical University, 29, Polytekhnicheskaya, 195251 Saint-Petersburg (Russian Federation)

    2013-11-21

    The influence of the BaF{sub 2} nanoparticle size on the intensity of the self-trapped exciton luminescence and the radiative core-valence transitions is studied by the luminescence spectroscopy methods using synchrotron radiation. The decrease of the self-trapped exciton emission intensity at energies of exciting photons in the range of optical exciton creation (hν ≤ E{sub g}) is less sensitive to the reduction of the nanoparticle sizes than in the case of band-to-band excitation, where excitons are formed by the recombination way. The intensity of the core-valence luminescence shows considerably weaker dependence on the nanoparticle sizes in comparison with the intensity of self-trapped exciton luminescence. The revealed regularities are explained by considering the relationship between nanoparticle size and photoelectron or photohole thermalization length as well as the size of electronic excitations.

  13. Commendable Eu2+-Doped Oxide-Matrix-Based LiBa12(BO3)7F4Red Broad Emission Phosphor Excited by NUV Light: Electronic and Crystal Structures, Luminescence Properties.

    Science.gov (United States)

    Ding, Xin; Wang, Yuhua

    2017-07-19

    In this work, we synthesized a new Eu 2+ -doped oxide-matrix-based LiBa 12 (BO 3 ) 7 F 4 broad red emission phosphor. It can emit red light peaking at ∼644 nm under NUV excitation with the coordinate at (0.6350, 0.3586) and a sensitive color gamut for eyes. This phosphor with a special kind of tunnel crystal structure and layered distribution of Ba 2+ is contributed to longer wavelength emission. By theoretical calculation and analysis using local state density energy band structure simulation of Eu 2+ doped in different site, the origin of the observed emission center was distinguished. Furthermore, decay curves analysis also indicated there are three possible Ba 2+ sites for Eu 2+ to occupy. Temperature-dependent PL spectra appeared anomalous phenomena that the intensity increases first and then decreases, which is due to the traps energy level's contribution of electron's transition. The phosphor also has cathodoluminescence (CL) property which the spectra take on typical current saturation phenomenon. The CL curves indicated that this phosphor has a very good stability under much electron beam bombardment time. After fabricated combining with BAM, (Sr, Ba) 2 SiO 4 and our red phosphor excited under 405-nm NUV chips, warm light LED was obtained. Its CIE coordinate is (0.3475, 0.3416) and the CCT, Ra, and luminous efficiency are 4856 K, 84.1, and 72.6 lm/W, respectively.

  14. Crystal structure and luminescence of complexes of Eu(III) and Tb(III) with furan-2,5-dicarboxylate

    NARCIS (Netherlands)

    Akerboom, S.; Fu, W.T.; Lutz, M.|info:eu-repo/dai/nl/304828971; Bouwman, E.

    2012-01-01

    Four new Ln(III) complexes (Ln = Eu, Tb) with furan-2,5-dicarboxylic acid (H2FDA) as a ligand have been synthesized and characterized in the solid state. Luminescence studies indicate that the compounds exhibit line-like luminescence characteristic of the lanthanide centre upon excitation in the

  15. Subdiffraction, Luminescence-Depletion Imaging of Isolated, Giant, CdSe/CdS Nanocrystal Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Lesoine, Michael D. [Ames Laboratory; Bhattacharjee, Ujjal [Ames Laboratory; Guo, Yijun [Ames Laboratory; Vela, Javier [Ames Laboratory; Petrich, Jacob W. [Ames Laboratory; Smith, Emily A. [Ames Laboratory

    2013-01-18

    Subdiffraction spatial resolution luminescence depletion imaging was performed with giant CdSe/14CdS nanocrystal quantum dots (g-NQDs) dispersed on a glass slide. Luminescence depletion imaging used a Gaussian shaped excitation laser pulse overlapped with a depletion pulse, shaped into a doughnut profile, with zero intensity in the center. Luminescence from a subdiffraction volume is collected from the central portion of the excitation spot, where no depletion takes place. Up to 92% depletion of the luminescence signal was achieved. An average full width at half-maximum of 40 ± 10 nm was measured in the lateral direction for isolated g-NQDs at an air interface using luminescence depletion imaging, whereas the average full width at half-maximum was 450 ± 90 nm using diffraction-limited, confocal luminescence imaging. Time-gating of the luminescence depletion data was required to achieve the stated spatial resolution. No observable photobleaching of the g-NQDs was present in the measurements, which allowed imaging with a dwell time of 250 ms per pixel to obtain images with a high signal-to-noise ratio. The mechanism for luminescence depletion is likely stimulated emission, stimulated absorption, or a combination of the two. The g-NQDs fulfill a need for versatile, photostable tags for subdiffraction imaging schemes where high laser powers or long exposure times are used.

  16. Physico-chemical characterizations of Cr doped persistent luminescence nanoparticles

    Science.gov (United States)

    Lecuyer, T.; Teston, E.; Maldiney, T.; Scherman, D.; Richard, C.

    2016-03-01

    Persistent luminescence nanoparticles have recently been proposed as innovative optical probes for small animal in vivo imaging. The main advantage of such probes is their ability to emit light for a long time after the end of their excitation, allowing in vivo imaging with low background. This work reports new information on the physico-chemical characterizations of Cr doped ZnGa2O4 nanoprobes in terms of synthetic procedure, luminescence properties as well as colloidal stabilities in different aqueous media and over the time.

  17. Excitonic surface polaritons in luminescence from ZnTe crystals

    Energy Technology Data Exchange (ETDEWEB)

    Brodin, M.S.; Bandura, V.M.; Matsko, M.G. (AN Ukrainskoj SSR, Kiev. Inst. Fiziki)

    1984-10-01

    The form and structure of reflection and exciton-polariton luminescence spectra of ZnTe crystals are studied in the region of the ground (n = 1) exciton state. The longitudinal-transverse splitting magnitude ..delta..E/sub LT/ is determined from the shape of the reflection spectra. A detected doublet structure of an emission band from the lower polariton branch is associated with the k-linear term. The evolution of bulk and surface polariton luminescence spectra versus temperature and wavelength of the exciting light is investigated.

  18. Mechanical grinding of a single-crystalline metal-organic framework triggered emission with tunable violet-to-orange luminescence.

    Science.gov (United States)

    Sun, Jian-Ke; Chen, Cheng; Cai, Li-Xuan; Ren, Cai-Xia; Tan, Bin; Zhang, Jie

    2014-12-28

    A metal-organic framework (MOF) featuring intriguing Borromean entanglement exhibits a unique mechanochromic luminescence with on-off switching. The concomitant excitation wavelength-dependent emission behavior can be utilized to tune the emission color from violet to orange.

  19. Measuring modulated luminescence using non-modulated stimulation: Ramping the sample period

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Andersen, C.E.

    2003-01-01

    Conventional methods of recording linearly modulated (LM) optically stimulated luminescence (OSL) require control over either the exciting light intensity, or the ability to pulse the source. For many light sources (e.g. constant-power CW lasers, arc lamps and synchrotrons) this can be problematic....... Directly analogous results to LM-OSL can, however, be achieved with non-modulated excitation sources, by ramping the sample period (RSP) of luminescence detection. RSP-OSL has the distinct advantage over LM-OSL in that, since the excitation remains at full power, data accumulation times (that can...

  20. Ion beam induced luminescence of materials

    CERN Document Server

    Brooks, R

    2001-01-01

    luminescence dead zone at the domain walls. Neodymium-yttrium-aluminium garnet (Nd:YAG) was examined and the spectra measured as a function of temperature to show the evolution of intensity of the narrow line emission from the Nd rare earth. Shifts and changes in the intrinsic UV band in the YAG material were also apparent. Thin films of alumina grown on silica on a silicon substrate, along with some that contained copper nanoclusters were also examined. TRIM software was used to model the rate of excitation within the different layers of the material for the various implant energies and to identify the source of the luminescence profile observed in each case. Evidence of thin film interference fringes was apparent in the spectra by fringe patterns modulated onto the luminescence signal as a function of wavelength and film thickness. Analysis of an alkali feldspar material using IBL, and combined with work done using RL and CL experiments, showed a shift towards lower wavelengths of the main red/IR band with ...

  1. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    1997-01-01

    The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

  2. Coherent effects in the relaxation dynamics of a multilevel quantum system excited by ultrashort light pulses

    Energy Technology Data Exchange (ETDEWEB)

    Averbukh, I.Sh; Kovarsky, V.A.; Perelman, N.F.

    1989-05-22

    Interference effects in luminescence produced by short light pulse excitation of a single quantum level interacting with a quasi-continuum of background states have been considered. Different regimes of subsequent luminescence quenching are revealed and analytically studied in a unified way: radiationless decay controlled emission, multiple repetitions of the initial pulse form, anharmonic dephasing and following revival, etc. (orig.).

  3. Effect of point defects on luminescence characteristics of ZnO ceramics

    Science.gov (United States)

    Rodnyi, P. A.; Chernenko, K. A.; Zolotarjovs, A.; Grigorjeva, L.; Gorokhova, E. I.; Venevtsev, I. D.

    2016-10-01

    Photo- and thermally stimulated luminescence of ZnO ceramics are produced by uniaxial hot pressing. The luminescence spectra of ceramics contain a wide band with a maximum at 500 nm, for which oxygen vacancies VO are responsible, and a narrow band with a maximum at 385 nm, which is of exciton nature. It follows from luminescence excitation spectra that the exciton energy is transferred to luminescence centers in ZnO. An analysis of the thermally stimulated luminescence curves allowed detection of a set of discrete levels of point defects with activation energies of 25, 45, 510, 590 meV, and defects with continuous energy distributions in the range of 50-100 meV. The parameters of some of the detected defects are characteristic of a lithium impurity and hydrogen centers. The photoluminescence kinetics are studied in a wide temperature range.

  4. Luminescent zinc metal-organic framework (ZIF-90) for sensing metal ions, anions and small molecules.

    Science.gov (United States)

    Liu, Chang; Yan, Bing

    2015-09-26

    We synthesize a zinc zeolite-type metal-organic framework, the zeolitic imidazolate framework (ZIF-90), which exhibits an intense blue luminescence excited under visible light. Luminescent studies indicate that ZIF-90 could be an efficient multifunctional fluorescence material for high sensitivity metal ions, anions and organic small molecules, especially for Cd(2+), Cu(2+), CrO4(2-) and acetone. The luminescence intensity of ZIF-90 increases with the concentration of Cd(2+) and decreases proportionally with the concentration of Cu(2+), while the same quenched experimental phenomena appear in the sensing of CrO4(2-). With the increase of the amount of acetone, the luminescence intensity decreases gradually in the emulsions of ZIF-90. The mechanism of the sensing properties is studied in detail as well. This study shows that ZIF-90 could be a useful luminescent sensor for metal ions, anions and organic small molecules.

  5. Power-dependent upconversion luminescence intensity in NaYF4,Yb3+,Er3+ nanoparticles

    Science.gov (United States)

    Li, A. H.; Lü, Q.

    2011-10-01

    The knowledge of the power density for which luminescence intensity reversal begins with power increase is of valuable importance for practical applications. Under 980 nm CW diode laser excitation, the maximum upconversion luminescence intensities were obtained at 4800, 5700, and 7100 W/cm2 for 2H9/2→4I15/2, 2H11/2&4S3/2→4I15/2, and 4F9/2→4I15/2 transition luminescences, respectively, in compact powder composed by cubic-phase NaYF4: Yb3+,Er3+ nanoparticles with a most probable diameter of ~46 nm. It was revealed experimentally that the reversal power density decreases as luminescent level rises. Excitation increase combined with radiative quantum efficiency decrease as power increase can reproduce this "n"-shape power dependence relationship.

  6. Preparation of ZnO nanoparticles showing upconversion luminescence through simple chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Anjana, R.; Subha, P. P.; Markose, Kurias K.; Jayaraj, M. K., E-mail: mkj@cusat.ac.in [Department of Physics, Cochin University of Science and Technology, Kochi, Kerala, India-682022 (India)

    2016-05-23

    Upconversion luminescence is an interesting area while considering its applications in a vast variety of fields. Rare earth ions like erbium is the most studied and efficient candidate for achieving upconversion. Erbium and ytterbium co-doped ZnO nanoparticles were prepared through co-precipitation method. A strong red emission has been obtained while exciting with 980 nm laser. Dependence of luminescence emission colour on ytterbium concentration has been studied.

  7. Preparation and luminescence of bulk oxyfluoride glasses doped with Ag nanoclusters.

    Science.gov (United States)

    Tikhomirov, V K; Rodríguez, V D; Kuznetsov, A; Kirilenko, D; Van Tendeloo, G; Moshchalkov, V V

    2010-10-11

    Bulk oxyfluoride glasses doped with Ag nanoclusters have been prepared using the melt quenching technique. When pumped in the absorption band of Ag nanoclusters between 300 to 500 nm, these glasses emit a very broad luminescence band covering all the visible range with a weak tail extending into the near infrared. The maximum of the luminescence band and its color shifts to the blue with a shortening of the excitation wavelength and an increasing ratio of oxide to fluoride components, resulting in white color luminescence at a particular ratio of oxide to fluoride; with a quantum yield above 20%.

  8. Optical spatial modulation of luminescent properties of van der Waals metal-organic framework

    Science.gov (United States)

    Milichko, Valentin A.; Makarov, Sergey V.

    2017-09-01

    UV light processing presents a facile means to tailor the properties of materials and structures. Metal-organic framework (MOF) with strong optical response has been realized through the incorporation of luminescent ligand within the van der Waals structure. The resulting MOF exhibits a significant one-photon excited luminesces change in response to UV light, enabling spatial modulation of the luminescent map of the MOF in micrometer scale. It thus demonstrates the capacity of patterning and data storage inside the crystal in a high resolution.

  9. OPTIMIZATION OF A BOXCAR INTEGRATOR AVERAGER SYSTEM FOR EXCITED-STATE LIFETIME MEASUREMENTS

    OpenAIRE

    NOVO, JBM; PESSINE, FBT

    1992-01-01

    The instrumental distortions due to adjustable parameters of the SR250 boxcar integrator/averager system and a pulsed-laser luminescence spectrometer on the excited-state lifetime decay waveforms were investigated. A theoretical model which takes into account the exponential moving average for this instrument and also RC distortion on the time-dependent luminescence signal is presented. An analytical expression relating the sample's excited-state lifetime and the adjustable instrumental param...

  10. Reusable temperature-sensitive luminescent material based on vitrified film of europium(III) β-diketonate complex

    Science.gov (United States)

    Lapaev, Dmitry V.; Nikiforov, Victor G.; Lobkov, Vladimir S.; Knyazev, Andrey A.; Galyametdinov, Yury G.

    2018-01-01

    We have proposed a novel temperature-sensitive luminescent material which is a 20 μm thick vitrified film (sandwiched between two quartz plates) fabricated from an amorphous powder of a mesogenic europium(III) β-diketonate complex through a melt-processing technique. The film photoexcited by a 337 nm pulsed nitrogen laser displays a typical Eu3+ ion luminescence bands with the strongest peak at 612 nm and with the decay time of 537 μs at 298 K. It is obtained that both the mean luminescence intensity and the luminescence decay time at 612 nm decrease significantly with temperature increasing from 298 to 348 K; the average values of the relative and absolute temperature sensitivities of the luminescence decay time in the range of 298-348 K are -1.2%·K-1 and -6.5 μs·K-1, respectively. The thermal quenching mechanism of the luminescent properties was analyzed and discussed. The experiments showed that, the luminescent properties of the film is insensitive to oxygen, the film is photostable under UV light, there is full reversibility of the temperature-dependent luminescence intensity and the decay time, and the high luminescence brightness of the film can be observed with violet light excitation. These factors indicated that the film is promising material for reusable luminescent thermometers, suitable for long-term monitoring in the range of 298-348 K.

  11. Luminescence of water or ice as a new detection method for magnetic monopoles

    Science.gov (United States)

    Pollmann, Anna Obertacke

    2017-12-01

    Cosmic ray detectors use air as a radiator for luminescence. In water and ice, Cherenkov light is the dominant light producing mechanism when the particle's velocity exceeds the Cherenkov threshold, approximately three quarters of the speed of light in vacuum. Luminescence is produced by highly ionizing particles passing through matter due to the electronic excitation of the surrounding molecules. The observables of luminescence, such as the wavelength spectrum and decay times, are highly dependent on the properties of the medium, in particular, temperature and purity. The results for the light yield of luminescence of previous measurements vary by two orders of magnitude. It will be shown that even for the lowest measured light yield, luminescence is an important signature of highly ionizing particles below the Cherenkov threshold. These could be magnetic monopoles or other massive and highly ionizing exotic particles. With the highest observed efficiencies, luminescence may even contribute significantly to the light output of standard model particles such as the PeV IceCube neutrinos. We present analysis techniques to use luminescence in neutrino telescopes and discuss experimental setups to measure the light yield of luminescence for the particular conditions in neutrino detectors.

  12. Luminescence and thermoluminescence of alkaline earth metaborates

    Energy Technology Data Exchange (ETDEWEB)

    Berezovskaya, I.V. [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya doroga, 65080 Odessa (Ukraine)], E-mail: physchem@paco.net; Efryushina, N.P. [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya doroga, 65080 Odessa (Ukraine); Voloshinovskii, A.S.; Stryganyuk, G.B. [Lviv Franko National University, 8 Kirilo i Mefodii str., 79005 Lviv (Ukraine); Pir, P.V.; Dotsenko, V.P. [Physico-Chemical Institute, Ukrainian Academy of Sciences, 86 Lustdorfskaya doroga, 65080 Odessa (Ukraine)

    2007-04-15

    The luminescent properties of undoped MB{sub 2}O{sub 4} (M=Ca, Sr) have been studied upon X-ray and synchrotron excitation. The X-ray induced emission spectra of CaB{sub 2}O{sub 4} consist mainly of two overlapping emission bands with maxima at about 3.19 and 3.65 eV. In addition to these features, there are several weak broad bands at lower energies. The excitation spectra of the dominant bands show an asymmetrical band with a sharp edge on the lower energy side and a maximum at 7.8 eV. This excitation band is ascribed to O 2p{yields}B 2s, 2p transitions within BO{sub 3} groups. The emission bands at 3.19 and 3.65 eV are tentatively ascribed to self-trapped excitons. Other emission bands with complicated excitation spectra are attributed to defects or impurities. TSL glow curve of CaB{sub 2}O{sub 4} after X-ray irradiation at 80 K consists of a stronger peak at about 132 K and weaker ones at 227, 272, 354 and 409 K. A comparison with the results on SrB{sub 2}O{sub 4} and the literature data on {alpha} ({beta})-modifications of BaB{sub 2}O{sub 4} is also made.

  13. New luminescent materials and filters for Luminescent Solar Concentrators

    NARCIS (Netherlands)

    De Boer, D.K.G.; Ronda, C.R.; Keur, W.C.; Meijerink, A.

    2012-01-01

    In a Luminescent Solar Concentrator (LSC), short-wavelength light isconverted by a luminescent material into long-wavelength light, which is guided towards a photovoltaic cell. In principle, an LSC allows for high concentration, but in practice this is prevented by lossmechanisms like limited

  14. Luminescence Properties of ScPO{sub 4} Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A.; Trukhin, A.N.

    1999-08-16

    Flux-grown ScPO{sub 4} single crystals exhibit a number of luminescence bands in their x-ray-excited luminescence spectra - including sharp lines arising from rare-earth elements plus a number of broad bands at 5.6 cV, 4.4 eV, and 3 eV. The band at 5.6 eV was attributed to a self-trapped exciton (STE) [l], and it could be excited at 7 eV and higher energies. This luminescence is strongly polarized (P = 70 %) along the optical axes of the crystal and exhibits a kinetic decay time constant that varies from several ns at room temperature to {approximately}10 {micro}s at 60 K and up to {approximately}1 ms at 10 K. It is assumed that the STE is localized on the SC ions. The band at 3 eV can be excited in the range of the ScPO{sub 4} crystal transparency (decay time = 3 to 4 {micro}s.) This band is attributed to a lead impurity that creates different luminescence centers. At high temperatures, the band at 4.4 eV is dominant in the x-ray-excited TSL and afterglow spectra. Its intensity increases with irradiation time beginning at zero at the initial irradiation time. The 4.4 eV band does not appear in a fast process under a pulsed electron beam, showing that accumulation is necessary for its observation. A sample of ScPO{sub 4} doped with vanadium exhibited a prevalent band at 4.4 eV at T = 480 K.

  15. Eu{sup 3+} luminescence in aluminophosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Nico, C., E-mail: claudionico@ua.pt [Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro (Portugal); Fernandes, R., E-mail: rugaliz.91@gmail.com [Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro (Portugal); Graça, M.P.F., E-mail: mpfg@ua.pt [Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro (Portugal); Elisa, M., E-mail: astatin89@yahoo.com [Department of Optospintronics, National Institute of R and D for Optoelectronics, INOE 2000, 77125 Magurele (Romania); Sava, B.A., E-mail: savabogdanalexandru@yahoo.com [Department of Optospintronics, National Institute of R and D for Optoelectronics, INOE 2000, 77125 Magurele (Romania); Monteiro, R.C.C., E-mail: rcm@fct.unl.pt [Department of Materials Science, CENIMAT/I3N, Faculty of Sciences and Technology, Universidade Nova de Lisboa, 2825-516 Caparica (Portugal); Rino, L., E-mail: lrino@ua.pt [Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro (Portugal); Monteiro, T., E-mail: tita@ua.pt [Department of Physics and I3N, University of Aveiro, 3810-193 Aveiro (Portugal)

    2014-01-15

    With a 4f{sup 6} electronic configuration, europium ions in the trivalent charge state are known to be efficient activators in wide band gap matrices. Embedded in the aluminophosphate (Li{sub 2}O–BaO–Al{sub 2}O{sub 3}–La{sub 2}O{sub 3}–P{sub 2}O{sub 5}) glasses the optically activated Eu{sup 3+} ions lead to intense room temperature orange/red luminescence with 16–23 Cd/m{sup 2} by using ultraviolet pumping. The as-prepared and heat treated europium doped glasses for temperatures below and above T{sub g} were studied by room temperature Raman spectroscopy, absorption, photoluminescence excitation, temperature dependent and time dependent photoluminescence. When the samples are excited by 325 nm wavelength photons, an enhancement of the red luminescence intensity by ca. one order of magnitude was found to occur for temperatures between 14 K and 350 K, for all the doped glasses. On the other hand, by using resonant excitation on the {sup 5}L{sub 6} Eu{sup 3+} excited state (λ{sub exc}∼390 nm) the ion emission intensity was found to be nearly constant for temperatures up to 500 K. For higher temperatures a steeper decrease of the luminescence intensity occurs due to non-radiative competitive channels described by activation energies of ca. 235 meV and 450 meV by using 325 and 390 nm wavelength photons as excitation, respectively. The lifetime of the {sup 5}D{sub 0} level in these glasses is ca. 2.93 ms. A discussion of the thermal population and de-excitation mechanisms is performed. -- Highlights: • Eu{sub 2}O{sub 3}–Li{sub 2}O–BaO–Al{sub 2}O{sub 3}–La{sub 2}O{sub 3}–P{sub 2}O{sub 5} glasses were prepared by a wet non-conventional quenching method. • Trivalent Eu were found to be optically activated in all glasses with an intense luminescence at RT. • PL intensity increases from 14 K to RT with indirect excitation, and remains almost constant with direct excitation. • A model that fits the thermal population and quenching mechanisms is

  16. Luminescence dating of delta sediments

    NARCIS (Netherlands)

    Chamberlain, Elizabeth L.; Wallinga, Jakob; Reimann, Tony; Goodbred, Steven L.; Steckler, Michael S.; Shen, Zhixiong; Sincavage, Ryan

    2017-01-01

    Deltas where luminescence dating is most essential due to organic-poor geologic records are also those where it is often most challenging due to unsuitable luminescence properties of quartz grains, associated with rapid production of young clastic sediment. One example is the

  17. Luminescence studies of semiconductor electrodes

    NARCIS (Netherlands)

    Kelly, J.J.; Kooij, Ernst S.; Meulenkamp, E.A.

    1999-01-01

    In this paper we review our recent results of in-situ luminescence studies of semiconductor electrodes. Three classes of materials are considered: single crystal compound semiconductors, porous silicon and semiconducting oxides doped with luminescent ions. We show how photoluminescence (PL) and

  18. Preparation and Characterisation of Sr2CeO4:Eu3+ Rare Earth Luminescent Material by High Temperature Mechano-Chemical Method

    National Research Council Canada - National Science Library

    Xue Yang Zhongbao Shao Hongqiang Ru

    2016-01-01

    ... ℃, and reached their maximum luminescent intensity at 900 ℃.Under ultraviolet excitation at 298 nm, the sample showed good luminescence with the strongest red light of 616 nm. However, Sr_2CeO_4:Eu~(3...

  19. A luminescent nisin biosensor

    Science.gov (United States)

    Immonen, Nina; Karp, Matti

    2006-02-01

    Nisin is a lantibiotic, an antibacterial peptide produced by certain Lactococcus lactis strains that kills or inhibits the growth of other bacteria. Nisin is widely used as a food preservative, and its long-time use suggests that it can be generally regarded as safe. We have developed a method for determining the amount of nisin in food samples that is based on luminescent biosensor bacteria. Bacterial luciferase operon luxABCDE was inserted into plasmid pNZ8048, and the construct was transformed by electroporation into Lc. lactis strain NZ9800, whose ability to produce nisin has been erased by deletion of the gene nisA. The operon luxABCDE has been modified to be functional in gram-positive bacteria to confer a bioluminescent phenotype without the requirement of adding an exogenous substrate. In the plasmid pNZ8048, the operon was placed under control of the nisin-inducible nisA promoter. The chromosomal nisRK genes of Lc. lactis NZ9800 allow it to sense nisin in the environment and relay this signal via signal transduction proteins NisK and NisR to initiate transcription from nisA promoter. In the case of our sensor bacteria, this leads to production of luciferase and, thus, luminescence that can be directly measured from living bacteria. Luminescence can be detected as early as within minutes of induction. The nisin assay described here provides a detection limit in the sub-picogram level per ml, and a linear area between 1 - 1000 pg/ml. The sensitivity of this assay exceeds the performance of all previously published methods.

  20. Luminescent macrocyclic lanthanide complexes

    Science.gov (United States)

    Raymond, Kenneth N [Berkeley, CA; Corneillie, Todd M [Campbell, CA; Xu, Jide [Berkeley, CA

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  1. Ion irradiation effect of alumina and its luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Yasushi; Yamamoto, Shunya; Naramoto, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; My, N.T.

    1997-03-01

    The luminescence spectra of single crystalline alpha-alumina and ruby which has 0.02% of Cr{sub 2}O{sub 3} as a impurity, induced by 200 keV He{sup +} and Ar{sup +} irradiation were measured at room temperature as a function of irradiation dose. The analysis of the measured spectra showed the existence of three main luminescence features in the wavelength region of 250 to 350 nm, namely anionic color centers, F-center at 411 nm and F{sup +}-center at 330 nm and a band observed around 315 nm. As alpha-alumina was irradiated with He{sup +}, F-center and F{sup +}-center luminescence grew and decayed, but the behaviors of those were different from each other. It seems that a concentration quenching occurred on the F-center luminescence in the dose range above 1x10{sup 14} He/cm{sup 2}. Furthermore, F-center luminescence was strongly suppressed in ruby, compared with that in alumina. On the other hand, the luminescence band around 315 nm appeared only in the early stage of irradiation and did not show its growth part. The dose dependent behavior was similar to that of Cr{sup 3+} emission at 695 nm (R-line) in ruby in both cases of He{sup +} and Ar{sup +} irradiation. Based on the experimental results mentioned above, the processes of defect formation and excitation in alumina in the early stage of ion irradiation will be discussed. (author)

  2. Optical and structural characterisation of low dimensional structures using electron beam excitation systems

    CERN Document Server

    Mohammed, A

    2000-01-01

    suppressed by nonradiative recombination centres. The temperatures at which the QW luminescence starts to quench and the activation energies of luminescence quenching are found to depend on excitation conditions, sample quality and QW depth. The results of CL intensity dependence on the excitation intensity revealed that luminescence from good quality QW structures is dominated by radiative recombination processes even at high temperatures during thermal quenching. In contrast, in defected structures non-radiative recombination mechanisms dominate the luminescence properties at all temperatures. Secondary electron images of hexagonal growth hillocks of GaN obtained at a range of electron beam excitation energies vary because of the different signals involved in the imaging. Electron backscatter diffraction measurements have been used for phase identification and lattice constants determination in a strained GaN epilayer. This thesis presents studies on optical and structural characterisation of low dimensiona...

  3. Enhanced radiation detectors using luminescent materials

    Energy Technology Data Exchange (ETDEWEB)

    Vardeny, Zeev V. (Holladay, UT); Jeglinski, Stefan A. (Durham, NC); Lane, Paul A. (Sheffield, GB)

    2001-01-01

    A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

  4. Luminescence and scintillation properties of LuPO{sub 4}-Ce nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Vistovskyy, V., E-mail: vistvv@gmail.com [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine); Malyy, T. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine); Pushak, A. [Ukraine Academy of Printing, 19 Pidgolosko Str., 79020 Lviv (Ukraine); Vas’kiv, A. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine); Shapoval, A.; Mitina, N. [Lviv Polytechnic National University, 12 S. Bandera, 79013 Lviv (Ukraine); Gektin, A. [Institute for Scintillation Materials, NAS of Ukraine, 60 Lenina Avenue, 61001 Kharkiv (Ukraine); Zaichenko, A. [Lviv Polytechnic National University, 12 S. Bandera, 79013 Lviv (Ukraine); Voloshinovskii, A. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya, 79005 Lviv (Ukraine)

    2014-01-15

    Study of the spectral-luminescence parameters of LuPO{sub 4}-Ce nanoparticles upon the excitation by X-ray quanta and synchrotron radiation with photon energies of 4–25 eV was performed. Nanoparticles with mean size about a=35 nm and nanoparticles with size less than 12 nm reveal the different structures of cerium centers. Luminescence efficiency of LuPO{sub 4}-Ce nanoparticles of a<12 nm size strongly decreases upon the excitation in the range of band-to-band transitions as well as in the case of X-ray excitation. -- Highlights: • Luminescence of LuPO{sub 4}-Ce nanoparticles studied using synchrotron and X-ray excitation. • Different structure of Ce{sup 3+}-centers has been revealed for LuPO{sub 4}-Ce nanoparticles. • Luminescence of LuPO{sub 4}-Ce with size less than 12 nm is strongly quenched upon the X-ray excitation.

  5. Luminescent solutions and powders of new samarium complexes with N,N',O,O'-chelating ligands

    Science.gov (United States)

    Kharcheva, Anastasia V.; Nikolskiy, Kirill S.; Borisova, Nataliya E.; Ivanov, Alexey V.; Reshetova, Marina D.; Yuzhakov, Viktor I.; Patsaeva, Svetlana V.

    2016-04-01

    Imaging techniques in biology and medicine are crucial tools to obtain information on structural and functional properties of living cells and organisms. To fulfill the requirements associated with application of these techniques it appears necessary to design markers with specific characteristics. Luminescent complexes of trivalent lanthanide ions with chelating ligands are of increasing importance in biomedical applications because of their millisecond luminescence lifetime, narrow emission band, high signal-to-noise ratio and minimal photodamage to biological samples. In order to extend the available emission wavelength range the luminescent samarium chelates are highly desirable. In this study the ligands with diamides of 2,2'-bipyridin-6,6'-dicarboxylic acid were used to improve photophysical characteristics of samarium complexes. We report the luminescence characteristics of samarium complexes with novel ligands. All complexes exhibited the characteristic emission of Sm (III) ion with the lines at 565, 597, 605, 645 and 654 nm, the intensity strongly depended on the ligand. Absorption and luminescence excitation spectra of Sm (III) complexes showed main peaks in the UV range demonstrating lanthanide coordination to the ligand. The absolute lumenescence quantum yield was measured for solutions in acetonitrile with excitation at 350 nm. The largest luminescence quantum yield was found for the samarium complex Bipy 6MePy Sm (3%) being much higher that for samarium complexes reported in the literature earlier. These results prove as well that samarium chelates are potential markers for multiparametric imaging techniques.

  6. White luminescence emission from silicon implanted germanium

    Science.gov (United States)

    Hernández, Angélica Guadalupe; Escobosa-Echavarría, Arturo Escobosa; Kudriavtsev, Yuriy

    2018-01-01

    Germanium crystals were implanted with low-energy and high-dose silicon ions. The implantation led to amorphization of a near-surface layer due to the formation of many adatoms and vacancies. Adatoms can be absorbed in germanium by the amorphous matrix faster than vacancies. The excess of vacancies and their ability to cluster resulted in formation of a porous structure beneath the surface. Pores of different sizes and depths were observed experimentally. A subsequent thermal annealing was carried out at 973 K in order to repair the damage due to the implantation. The annealing resulted, among other things, in oxidation of the pores. Visible white luminescence was observed for the as-implanted samples at the 325 nm excitation wavelength; the photoluminescence intensity increased after the annealing. The optical properties were attributed to the combined effects of different defects and the formation of germanium oxides with oxygen deficiencies.

  7. Homogeneous broadening effect on temperature dependence of green upconversion luminescence in erbium doped fibers

    Energy Technology Data Exchange (ETDEWEB)

    Egatz-Gómez, A. [Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Arcos de Jalón 118, Madrid 28037 (Spain); Department of Biomedical Engineering, Texas A and M University, College Station, TX 77843 (United States); Calderón, Oscar G., E-mail: oscargc@fis.ucm.es [Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Arcos de Jalón 118, Madrid 28037 (Spain); Melle, Sonia; Carreño, F.; Antón, M.A. [Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Arcos de Jalón 118, Madrid 28037 (Spain); Gort, Elske M. [Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Arcos de Jalón 118, Madrid 28037 (Spain); Department of Biomedical Engineering, University of Groningen, 9700 RB Groningen (Netherlands)

    2013-07-15

    We study the green upconversion luminescence of Er{sup 3+} ions in an aluminosilicate optical fiber upon near infrared excitation at 787 nm. The dependence of the upconversion luminescence on temperature has been determined. As temperature drops from room to cryogenic temperatures, the upconversion green emission reaches a maximum around 40 K, and then decreases. A nearly quadratic dependence of the upconversion luminescence with excitation power is found, which is consistent with a sequential stepwise two-photon absorption process. These results have been explained with a semiclassical model that considers the inhomogeneous broadening of the optical transitions due to glass imperfections, and the dependence of the homogeneous linewidth broadening on temperature. -- Highlights: ► We study green upconversion luminescence of Er{sup 3+} ions in a fiber excited at 787 nm. ► Upconversion luminescence variation from room to cryogenic temperature is analyzed. ► Upconversion emission consists in a sequential two-photon absorption process. ► A semiclassical model considering inhomogeneous broadening explains the results. ► Homogeneous broadening is responsible for the upconversion temperature dependence.

  8. Temperature lags of luminescence measurements in a commercial luminescence reader

    Energy Technology Data Exchange (ETDEWEB)

    Kitis, George [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece); Kiyak, Nafiye G. [ISIK University, Faculty of Science and Arts, Physics Department, Sile, 34980 Istanbul (Turkey); Polymeris, George S., E-mail: gspolymeris@ankara.edu.tr [Ankara University, Institute of Nuclear Sciences, Beşevler, 06100 Ankara (Turkey)

    2015-09-15

    The temperature recorded in thermoluminescence and optically stimulated luminescence equipments is not the temperature of the sample but that of the heating element on which the thermocouple is attached. Depending upon the rate of heating, a temperature difference appears between the samples and the heating element, termed as temperature lag, which could have serious effects on the curve shapes and trapping parameters. In the present work the temperature lag effect is studied in a newly developed luminescence equipment measuring both thermoluminescence and optically stimulated luminescence. It is found that the temperature lag could be large for heating rates above 2 K/s and it is strongly dependent upon the sample holder. A simple approximation method is proposed in order to both predict as well as correct for temperature lag effects in luminescence measurements.

  9. Deep-red persistent luminescence in Cr3+-doped LaAlO3 perovskite phosphor for in vivo imaging

    Science.gov (United States)

    Katayama, Yumiko; Kobayashi, Hiroaki; Tanabe, Setsuhisa

    2015-01-01

    We report deep-red long-lasting persistent luminescence in Cr3+-doped LaAlO3 perovskite phosphor synthesized by solid-state reaction. The LaAlO3:Cr3+ sample showed persistent luminescence peaking at a very long wavelength of 734 nm due to Cr3+:2E → 4A2 transition after ultraviolet excitation. The Sm3+ ion was found to be a good codopant for increasing the persistent luminescence intensity more than 35-fold. For the Cr3+-Sm3+-codoped LaAlO3 sample, the radiance of persistent luminescence in mW sr-1 m-2 unit was higher than or comparable to that of ZnGa2O4:Cr3+ phosphor, which is a candidate phosphor with a peak luminescence at 694 nm for in vivo imaging application.

  10. Excited Delirium

    Directory of Open Access Journals (Sweden)

    Takeuchi, Asia

    2011-02-01

    Full Text Available Excited (or agitated delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. [West J Emerg Med. 2011;12(1:77-83.

  11. Lanthanide doped ultrafine hybrid nanostructures: multicolour luminescence, upconversion based energy transfer and luminescent solar collector applications.

    Science.gov (United States)

    Singh, Priyam; Shahi, Praveen Kumar; Singh, Sunil Kumar; Singh, Akhilesh Kumar; Singh, Manish Kumar; Prakash, Rajiv; Rai, Shyam Bahadur

    2017-01-05

    We herein demonstrate novel inorganic-organic hybrid nanoparticles (HNPs) composed of inorganic NPs, NaY0.78Er0.02Yb0.2F4, and an organic β-diketonate complex, Eu(TTA)3Phen, for energy harvesting applications. Both the systems maintain their core integrity and remain entangled through weak interacting forces. HNPs incorporate the characteristic optical behaviour of both the systems i.e. they give an intense red emission under UV excitation, due to Eu3+ in organic complexes, and efficient green upconversion emission of Er3+ in inorganic NPs for NIR (980 nm) excitation. However, (i) an energy transfer from Er3+ (inorganic NPs) to Eu3+ (organic complex) under NIR excitation, and (ii) an increase in the decay time of 5D0 → 7F2 transition of Eu3+ for HNPs as compared to the Eu(TTA)3Phen complex, under different excitation wavelengths, are added optical characteristics which point to an important role of the interface between both the systems. Herein, the ultra-small size (6-9 nm) and spherical shape of the inorganic NPs offer a large surface area, which improves the weak interaction force between both the systems. Furthermore, the HNPs dispersed in the PMMA polymer have been successfully utilized for luminescent solar collector (LSC) applications.

  12. Luminescent metal-organic frameworks.

    Science.gov (United States)

    Allendorf, M D; Bauer, C A; Bhakta, R K; Houk, R J T

    2009-05-01

    Metal-organic frameworks (MOFs) display a wide range of luminescent behaviors resulting from the multifaceted nature of their structure. In this critical review we discuss the origins of MOF luminosity, which include the linker, the coordinated metal ions, antenna effects, excimer and exciplex formation, and guest molecules. The literature describing these effects is comprehensively surveyed, including a categorization of each report according to the type of luminescence observed. Finally, we discuss potential applications of luminescent MOFs. This review will be of interest to researchers and synthetic chemists attempting to design luminescent MOFs, and those engaged in the extension of MOFs to applications such as chemical, biological, and radiation detection, medical imaging, and electro-optical devices (141 references).

  13. Luminescence properties of solid solutions LuxY1-xPO4:Eu3+

    Science.gov (United States)

    Levushkina, V. S.; Spassky, D. A.; Tretyakova, M. S.; Zadneprovski, B. I.; Kamenskikh, I. A.; Vasil'ev, A. N.; Belsky, A.

    2018-01-01

    Solid solutions LuxY1-xPO4 doped with Eu3+ were synthesized by the sol-gel method. Luminescence spectra under UV and X-ray excitation and luminescence excitation spectra in the UV-VUV energy range are presented. Observed variations of the structure of 4f-4f Eu3+ lines with the composition of the solid solution are explained by the fluctuations in the distribution of substitutional cations. The role of electronic structure modification in the fundamental absorption region with changing Y/Lu ratio is discussed and is suggested as the origin of different efficiency of energy transfer to Eu3+ in this region. Temperature dependence of the luminescence yield is related to the competition between emission centers and traps.

  14. The effect of Bi{sup 3+} and Li{sup +} co-doping on the luminescence characteristics of Eu{sup 3+}-doped aluminum oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Padilla-Rosales, I., E-mail: ipadilla@cinvestav.mx [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Martinez-Martinez, R. [Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, CP 69000 Huajuapan de León, Oax, México (Mexico); Cabañas, G. [Centro de Investigación y de Estudios Avanzados del IPN, Nanociencias y Nanotecnología, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico); Falcony, C. [Centro de Investigación y de Estudios Avanzados del IPN, Departamento de Física, Av. IPN 2508, Col. San Pedro Zacatenco, CP 07360 México D.F. (Mexico)

    2015-09-15

    The incorporation of Bi{sup 3+} and Li{sup +} as co-dopants in Eu{sup 3+}-doped aluminum oxide films deposited by the ultrasonic spray pyrolysis technique and its effect on the luminescence characteristics of this material are described. Both Bi{sup 3+} and Li{sup +} do not introduce new luminescence features but affect the luminescence intensity of the Eu{sup 3+} related emission spectra as well as the excitation spectra. The introduction of Bi{sup 3+} generates localized states in the aluminum oxide host that result in a quenching of the luminescence intensity, while Li{sup +} and Bi{sup 3+} co-doping increase the luminescence intensity of these films. - Highlights: • Li and Bi co-doping increase the luminescence. • Bi creates localized states in the Al{sub 2}O{sub 3} host. • Li was incorporated as a co-activator.

  15. Dependences of up-conversional luminescence of LiNbO3:Yb3+, Er3+ crystals on pump intensity

    Science.gov (United States)

    Babajanyan, V. G.; Kostanyan, R. B.; Muzhikyan, P. H.; Sargsyan, R. V.

    2010-10-01

    The up-converted luminescence at 525, 550 nm and 670 nm wavelengths, as well as the ordinary luminescence near 1600 nm wavelength of the LiNbO3:Yb3+, Er3+ crystal are investigated under optical excitations at 808 nm and 980 nm. Dependencies of luminescence on intensities of optical pumping at both wavelengths are presented. The possible mechanisms of up-converted emissions obtaining as well as population mechanisms of the Er3+ ion 4I13/2 energy level in the LiNbO3 matrix are discussed.

  16. Luminescence spectroscopy of Rb2KTiOF5 oxyfluoride single crystals

    Science.gov (United States)

    Kozlov, A. V.; Pustovarov, V. A.; Sarychev, M. N.; Isaenko, L. I.

    2017-09-01

    Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.5 eV, PL excitation spectra using synchrotron radiation (3.7-22 eV), time-resolved impulse cathode-luminescence (ICL) spectra, the temperature depending of the XRL, decay kinetics as well as thermoluminescence curves were measured for single crystals Rb2KTiOF5, a promising nonlinear optical material. Single crystals are transparent in microwave, visible and near UV range, inter-band transition energy is Eg = 4.2 eV. Crystalline structure has two disordered mixed position O/F, phase transition in the region of 215 K. All the obtained results indicate that in luminescence spectra nonelementary band 2.2 eV is connected to the emission of self-trapped excitons. Nonelementary band 2.2 eV associated with the presence local distortion in the octahedron TiOF5. It is observed that at interband excitation in VUV region at energies more than 3.5 Eg the effect of multiplication of electronic excitations appears. That determines the high output of XRL and ICL. Luminescence methods of quality control of grown crystals are proposed.

  17. Singlet oxygen luminescence detection with a fiber-coupled superconducting nanowire single-photon detector

    NARCIS (Netherlands)

    Gemmell, N.R.; McCarthy, A.; Liu, B.; Tanner, M.G.; Dorenbos, S.N.; Zwiller, V.; Patterson, M.S.; Buller, G.S.; Wilson, B.C.; Hadfield, R.H.

    2013-01-01

    Direct monitoring of singlet oxygen (1O2) luminescence is a particularly challenging infrared photodetection problem. 1O2, an excited state of the oxygen molecule, is a crucial intermediate in many biological processes. We employ a low noise superconducting nanowire single-photon detector to record

  18. Luminescence properties of terbium-doped Li3PO4 phosphor for ...

    Indian Academy of Sciences (India)

    The powder X-ray diffraction (PXRD), photoluminescence (PL) emission and excitation spectra, thermoluminescence (TL) and optically stimulated luminescence (OSL) were measured. The particle size was calculated using the Debye Scherrer formula and found to be 79.42 nm. PL emission spectra of Li 3 PO 4 :Tb 3 + ...

  19. Power dependence of upconversion luminescence in lanthanide and transition-metal-ion systems

    NARCIS (Netherlands)

    Pollnau, Markus; Gamelin, D.R.; Lüthi, S.R.; Güdel, H.U.; Hehlen, M.P.

    2000-01-01

    We show theoretically with the simplest possible model that the intensity of an upconversion luminescence that is excited by the sequential absorption of n photons has a dependence on absorbed pump power P, which may range from the limit of Pn down to the limit of P1 for the upper state and less

  20. Luminescent materials for modern light sources

    Science.gov (United States)

    Zak, P. P.; Lapina, V. A.; Pavich, T. A.; Trofimov, A. V.; Trofimova, N. N.; Tsaplev, Yu B.

    2017-09-01

    The studies dealing with luminescent materials for semiconductor lighting are surveyed. The luminescent materials are classified in terms of the class of chemical compounds they belong to and in terms of the way they are used in luminescent converters of light from the primary light source. The use of inorganic phosphors, organic luminescent materials and materials based on complex compounds, quantum dots and metal-organic frameworks are considered. Sequential and parallel luminescent converters are defined. The key problems are identified and the possible ways of addressing them are outlined. Particular attention is paid to the problem of photodegradation of luminescent converters. The bibliography includes 101 references.

  1. Modelling the luminescence of iridium cyclometalated complexes encapsulated in cucurbituril.

    Science.gov (United States)

    Alrawashdeh, Lubna R; Cronin, Michael P; Day, Anthony I; Wallace, Lynne; Woodward, Clifford E

    2018-01-15

    Iridium(iii) cyclometalated complexes in aqueous solution often display relatively weak luminescence. It has been shown in previous work that this emission can be significantly enhanced (by up to two orders of magnitude) by encapsulation in cucurbit[10]uril (Q[10]). Luminescence lifetime measurements suggest a dynamic self-quenching mechanism is active, possibly due to displacement of an excited guest complex via collision with an unbound complex. We devise a model for the association of a group of iridium(iii) cyclometalated complexes with Q[10]. The model parameters are then fitted to steady-state emission titration curves. The excellent agreement of experimental data with the model provides valuable mechanistic information relating to the way this class of metal complexes interact and associate with the Q[10] host.

  2. Two porous luminescent metal-organic frameworks: quantifiable evaluation of dynamic and static luminescent sensing mechanisms towards Fe(3.).

    Science.gov (United States)

    Jin, Jun-Cheng; Pang, Ling-Yan; Yang, Guo-Ping; Hou, Lei; Wang, Yao-Yu

    2015-10-21

    Two novel porous luminescent metal-organic frameworks (MOFs, 1 and 2) have been constructed using 3,4-di(3,5-dicarboxyphenyl)phthalic acid using a hydrothermal method. Both MOFs can work as highly sensitive sensors to Fe(3+) by luminescent quenching. Analyses of the structures indicate a higher quenching efficiency of 2 because of the existence of active -COOH groups. Based on this consideration, the quenching mechanisms are studied and the processes are controlled by multiple mechanisms in which dynamic and static mechanisms of MOFs are discussed. Besides, the corresponding dynamic and static quenching constants are calculated, achieving the quantification evaluation of the quenching process. As expected, experimental data show that compound 2 possesses an overall quenching efficiency 6.9 times that of compound 1. Additionally, time-dependent intensity measurements, the shifts of the excitation spectrum and the appearance of a new emission peak all give visual proofs of the distinct mechanisms between the two MOFs.

  3. Luminescent ion pairs with tunable emission colors for light-emitting devices and electrochromic switches.

    Science.gov (United States)

    Guo, Song; Huang, Tianci; Liu, Shujuan; Zhang, Kenneth Yin; Yang, Huiran; Han, Jianmei; Zhao, Qiang; Huang, Wei

    2017-01-01

    Most recently, stimuli-responsive luminescent materials have attracted increasing interest because they can exhibit tunable emissive properties which are sensitive to external physical stimuli, such as light, temperature, force, and electric field. Among these stimuli, electric field is an important external stimulus. However, examples of electrochromic luminescent materials that exhibit emission color change induced by an electric field are limited. Herein, we have proposed a new strategy to develop electrochromic luminescent materials based on luminescent ion pairs. Six tunable emissive ion pairs ( IP1-IP6 ) based on iridium(iii) complexes have been designed and synthesized. The emission spectra of ion pairs (IPs) show concentration dependence and the energy transfer process is very efficient between positive and negative ions. Interestingly, IP6 displayed white emission at a certain concentration in solution or solid state. Thus, in this contribution, UV-chip (365 nm) excited light-emitting diodes showing orange, light yellow and white emission colors were successfully fabricated. Furthermore, IPs displayed tunable and reversible electrochromic luminescence. For example, upon applying a voltage of 3 V onto the electrodes, the emission color of the solution of IP1 near the anode or cathode changed from yellow to red or green, respectively. Color tunable electrochromic luminescence has also been realized by using other IPs. Finally, a solid-film electrochromic switch device with a sandwiched structure using IP1 has been fabricated successfully, which exhibited fast and reversible emission color change.

  4. Solubility of YAG:Nd in borate glass-luminescence and Raman investigation

    Energy Technology Data Exchange (ETDEWEB)

    Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 Wroclaw (Poland); Solarz, P., E-mail: solarz@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 Wroclaw (Poland); Kasprowicz, D.; Runka, T. [Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13 A, 60-965 Poznan (Poland); Szysiak, A.; Stepien, R. [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland)

    2011-05-26

    Highlights: > In the present work we investigate glass-ceramic systems obtained by melting the sintered samples mentioned above. > Intention of the work is to get a more close insight into the nature of luminescent centres in these materials. In the first approach low temperature luminescence spectra recorded upon a bulk excitation, denoted as 'macroscopic' are analysed to assess the effect of the solubility of crystalline phase. > In the second approach denoted as 'microscopic' selected areas of samples were illuminated by an incident light beam with a diameter of about 1 micrometer and resulting Raman scattering spectra and luminescence spectra are compared. - Abstract: YAG:Nd powders obtained by grinding a single crystal and synthesized by modified sol-gel and combustion methods were embedded at the stage of melting in a multicomponent borate glass to obtain luminescent glass-ceramic systems. Room temperature optical absorption spectra, luminescence spectra at room temperature and at 10 K and micro-Raman spectra were recorded to determine the location of Nd{sup 3+} ions in composite materials. It has been concluded that their luminescence characteristics depend critically on the preparation method hence the morphology of precursor crystalline YAG:Nd powders as a consequence of dissimilar solubility of crystallites in a host glass.

  5. Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

    Science.gov (United States)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and

  6. Self absorption in luminescent solar concentrators

    NARCIS (Netherlands)

    Krumer, Z.

    2014-01-01

    Luminescent solar concentrators are photovoltaic devices made of thin transparent material, in which luminescent particles are dispersed. The incident light enters the device through its large facets and is subsequently absorbed by the luminescent particles, which re-emit it whilst changing its

  7. Solvothermal chemistry of luminescent lanthanide fluorides

    OpenAIRE

    Jayasundera, Anil

    2009-01-01

    Exploration of novel lanthanide fluoride framework materials in inorganic-organic hybrid systems under solvothermal conditions towards development of new luminescent materials is discussed. X-ray single crystal and powder diffraction methods have been used as crystallographic characterisation techniques. Determination and study of luminescence properties for selected hybrid materials has also been carried out. The first organically templated luminescent lanthanide fluoride fram...

  8. Near-surface layer radiation color centers in lithium fluoride nanocrystals: Luminescence and composition

    Energy Technology Data Exchange (ETDEWEB)

    Voitovich, A.P., E-mail: voitovich@imaph.bas-net.by; Kalinov, V.S.; Stupak, A.P.; Novikov, A.N.; Runets, L.P.

    2015-01-15

    Lithium fluoride nanocrystals are irradiated by gamma quanta at 77 K. The radiation color centers formed in a near-surface layer of nanocrystals are studied. Absorption, luminescence and luminescence excitation spectra of the surface defects have been measured. It has been found that the luminescence excitation spectra for aggregated surface centers consist of two or three bands with not very much different intensities. Reactions of the surface centers separately with electrons and with anion vacancies have been investigated. Numbers of anion vacancies and electrons entering into the centers composition have been established and it has been found that F{sub S1}, F{sub S1}{sup −}, F{sub S2}, F{sub S2}{sup −}, F{sub S3}{sup +} and F{sub S3} types of the surface centers are formed. The degree of luminescence polarization has been defined and it has been determined that the polarization degree for F{sub S2}{sup +} centers changes sign under transition from one excitation band to another. It has been shown that during irradiation at 77 K radiation-induced defects are formed more efficiently on the surface than in the bulk. - Highlights: • Radiative color centers were fabricated in lithium fluoride nanocrystals. • The unique absorption and luminescence characteristics are inherent in the centers. • The reactions of these centers with electrons and anion vacancies were studied. • The degree of luminescence polarization was defined. • Numbers of anion vacancies and electrons forming the centers were established.

  9. Near Infrared Quantum Cutting Luminescence of Er3+/Tm3+ Ion Pairs in a Telluride Glass.

    Science.gov (United States)

    Chen, Xiaobo; Li, Song; Hu, Lili; Wang, Kezhi; Zhao, Guoying; He, Lizhu; Liu, Jinying; Yu, Chunlei; Tao, Jingfu; Lin, Wei; Yang, Guojian; Salamo, Gregory J

    2017-05-16

    The multiphoton near-infrared, quantum cutting luminescence in Er3+/Tm3+ co-doped telluride glass was studied. We found that the near-infrared 1800-nm luminescence intensity of (A) Er3+(8%)Tm3+(0.5%):telluride glass was approximately 4.4 to 19.5 times larger than that of (B) Tm3+(0.5%):telluride glass, and approximately 5.0 times larger than that of (C) Er3+(0.5%):telluride glass. Additionally, the infrared excitation spectra of the 1800 nm luminescence, as well as the visible excitation spectra of the 522 nm and 652 nm luminescence, of (A) Er3+(8%)Tm3+(0.5%):telluride glass are very similar to those of Er3+ ions in (C) Er3+(0.5%):telluride glass, with respect to the shapes of their excitation spectral waveforms and peak wavelengths. Moreover, we found that there is a strong spectral overlap and energy transfer between the infrared luminescence of Er3+ donor ions and the infrared absorption of Tm3+ acceptor ions. The efficiency of this energy transfer {4I13/2(Er3+) → 4I15/2(Er3+), 3H6(Tm3+) → 3F4(Tm3+)} between the Er3+ and Tm3+ ions is approximately 69.8%. Therefore, we can conclude that the observed behaviour is an interesting multiphoton, near-infrared, quantum cutting luminescence phenomenon that occurs in novel Er3+-Tm3+ ion pairs. These findings are significant for the development of next-generation environmentally friendly germanium solar cells, and near-to-mid infrared (1.8-2.0 μm) lasers pumped by GaN light emitting diodes.

  10. A luminescent nanocrystal stress gauge

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Charina; Koski, Kristie; Olson, Andrew; Alivisatos, Paul

    2010-10-25

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe/CdS core/shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress, and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution.

  11. Interplay between chromium content and lattice disorder on persistent luminescence of ZnGa{sub 2}O{sub 4}:Cr{sup 3+} for in vivo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Suchinder K.; Bessière, Aurelie [Institut de Recherche de Chimie-Paris, CNRS – Chimie-ParisTech, 11 rue Pierre et Marie Curie, 75005 Paris (France); Basavaraju, Neelima; Priolkar, Kaustubh R. [Department of Physics, Goa University, Goa 403206 (India); Binet, Laurent; Viana, Bruno [Institut de Recherche de Chimie-Paris, CNRS – Chimie-ParisTech, 11 rue Pierre et Marie Curie, 75005 Paris (France); Gourier, Didier, E-mail: didier.gourier@chimie-paristech.fr [Institut de Recherche de Chimie-Paris, CNRS – Chimie-ParisTech, 11 rue Pierre et Marie Curie, 75005 Paris (France)

    2014-11-15

    In the quest of bright and long persistent far-red/near-infrared phosphors for in vivo optical imaging, the interest in the family of ZnGa{sub 2}O{sub 4} spinel compounds doped with Cr{sup 3+} has been aroused in the most recent years. We show that the dopant concentration plays an important role in the total persistent luminescence output of the material. ZnGa{sub 2}O{sub 4} doped with 0.25%, 0.50% and 0.75% Cr relative to (Ga+Cr) was prepared by solid state synthesis. 0.50% Cr was found optimal to obtain the most intense persistent luminescence after matrix excitation with X-rays or localized excitation in Cr{sup 3+} absorption band with 550 nm wavelength. Up to 0.5% Cr content, persistent luminescence increases as a consequence of an increased number of Cr{sup 3+} luminescent centers and associated defects. With 0.75% Cr content, a too large number of defects locally concentrated around Cr{sup 3+} ions are detrimental to the long-term persistent luminescence intensity. We supplement long lasting phosphorescence investigation with laser excited photoluminescence and thermally stimulated luminescence results. - Highlights: • The red persistent luminescence of ZnGa{sub 2}O{sub 4}:Cr is optimum for 0.50% Cr{sup 3+} doping. • Higher doping introduces lattice disorder. • The phenomenon is studied by correlating photoluminescence, EPR and thermoluminescence.

  12. Quantitative Luminescence Imaging System

    Energy Technology Data Exchange (ETDEWEB)

    Batishko, C.R.; Stahl, K.A.; Fecht, B.A.

    1992-12-31

    The goal of the MEASUREMENT OF CHEMILUMINESCENCE project is to develop and deliver a suite of imaging radiometric instruments for measuring spatial distributions of chemiluminescence. Envisioned deliverables include instruments working at the microscopic, macroscopic, and life-sized scales. Both laboratory and field portable instruments are envisioned. The project also includes development of phantoms as enclosures for the diazoluminomelanin (DALM) chemiluminescent chemistry. A suite of either phantoms in a variety of typical poses, or phantoms that could be adjusted to a variety of poses, is envisioned. These are to include small mammals (rats), mid-sized mammals (monkeys), and human body parts. A complete human phantom that can be posed is a long-term goal of the development. Taken together, the chemistry and instrumentation provide a means for imaging rf dosimetry based on chemiluminescence induced by the heat resulting from rf energy absorption. The first delivered instrument, the Quantitative Luminescence Imaging System (QLIS), resulted in a patent, and an R&D Magazine 1991 R&D 100 award, recognizing it as one of the 100 most significant technological developments of 1991. The current status of the project is that three systems have been delivered, several related studies have been conducted, two preliminary human hand phantoms have been delivered, system upgrades have been implemented, and calibrations have been maintained. Current development includes sensitivity improvements to the microscope-based system; extension of the large-scale (potentially life-sized targets) system to field portable applications; extension of the 2-D large-scale system to 3-D measurement; imminent delivery of a more refined human hand phantom and a rat phantom; rf, thermal and imaging subsystem integration; and continued calibration and upgrade support.

  13. A study of marine luminescence signatures, part 1

    Science.gov (United States)

    Hornig, A. W.; Eastwood, D.

    1973-01-01

    Fluorescent excitation and emission spectral data on chlorophyll and Gelbstoff in natural sea waters from the Atlantic, Gulf, and Pacific coasts show that algae particulates are totally absorbing over much of the near ultraviolet and visible spectra and act approximately as quantum counters; plant pigments absorb energy and transfer a large portion to chlorophyll where some fraction is emitted as chlorophyll fluorescence. Gelbstoff data do not exhibit quantum counter action because of their low concentration. It is concluded that luminescence data of natural sea waters are useful in monitoring algal and Gelbstoff as well as pollutant concentrations.

  14. Luminescent materials and their applications

    CERN Document Server

    Virk, Hardev Singh

    2015-01-01

    It is pertinent to note that Luminescence phenomenon has once again occupied a central stage with the announcement of Nobel Prize in October 2014 to three Japanese scientists. The discovery of Galium Nitride proved to be a revolutionary step forward in creation of Blue LEDs. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources. The Volume under reference consists of 9 Chapters, written by experts in the area of Luminescent Materials. First 5 Chapters are contributed as Review Papers and the last 4 are based on Research Papers.Chapter

  15. Use of an airborne Fraunhofer line discriminator for the detection of solar stimulated luminescence

    Science.gov (United States)

    Watson, Robert D.; Hemphill, William R.

    1976-01-01

    Luminescence is the property of some materials to emit light when excited by external stimuli such as ultraviolet or visible light or by chemical or mechanical action. The Fraunhofer line discriminator (FLO) is an airborne electro-optical device which operates as a non-imaging radiometer and permits detection of solar stimulated luminescence several orders of magnitude below the intensity detectable with the human eye. A prototype FLO, used in 1969 to monitor the dynamic of water currents in the San Francisco area, was than 5 parts per

  16. Silica-modified luminescent LaPO4:Eu@LaPO4@SiO2core/shell nanorods: Synthesis, structural and luminescent properties.

    Science.gov (United States)

    Ansari, Anees A

    2018-02-01

    Monoclinic-type tetragonal LaPO 4 :Eu (core) and LaPO 4 :Eu@LaPO 4 (core/shell) nanorods (NRs) were successfully prepared using a urea-based co-precipitation process under ambient conditions. An amorphous silica layer was coated around the luminescent core/shell NRs via the sol-gel process to improve their solubility and colloidal stability in aqueous and non-aqueous media. The prepared nano-products were systematically characterized by X-ray diffraction pattern, transmission electron microscopy, energy dispersive X-ray analysis, and FTIR, UV/Vis, and photoluminescence spectroscopy to examine their phase purity, crystal phase, surface chemistry, solubility and luminescence characteristics. The length and diameter of the nano-products were in the range 80-120 nm and 10-15 nm, respectively. High solubility of the silica-modified core/shell/Si NRs was found for the aqueous medium. The luminescent core NRs exhibited characteristic excitation and emission transitions in the visible region that were greatly affected by surface growth of insulating LaPO 4 and silica layers due to the multiphonon relaxation rate. Our luminescence spectral results clearly show a distinct difference in intensities for core, core/shell, and core/shell/Si NRs. Highly luminescent NRs with good solubility could be useful candidates for a variety of photonic-based biomedical applications. Copyright © 2017 John Wiley & Sons, Ltd.

  17. Metal-organic frameworks for luminescence thermometry.

    Science.gov (United States)

    Cui, Yuanjing; Zhu, Fengliang; Chen, Banglin; Qian, Guodong

    2015-05-01

    Metal-organic frameworks (MOFs) hold great promise for developing various types of luminescent sensors due to their remarkable structural diversity and tunable luminescence properties. In the last few years, utilizing luminescent MOFs to explore temperature sensing has gained intense attention. In this feature article, after the general description of luminescence thermometry, we have summarized the recent progress made in luminescent MOF thermometers, with particular emphasis on the dual-emitting MOFs that effectively illustrate the self-referencing temperature measurement based on the intensity ratios of two separate transitions.

  18. Effect of particle size and morphology on the properties of luminescence in ZnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Lisitsyn, V.M. [National Research Tomsk Polytechnic University, Lenin Avenue, 30, 634050 Tomsk (Russian Federation); Valiev, D.T., E-mail: dtdamirka@gmail.com [National Research Tomsk Polytechnic University, Lenin Avenue, 30, 634050 Tomsk (Russian Federation); Tupitsyna, I.A.; Polisadova, E.F. [Institute for Scintillation Materials, Lenin Avenue, 60, Kharkov 61001 (Ukraine); Oleshko, V.I. [National Research Tomsk Polytechnic University, Lenin Avenue, 30, 634050 Tomsk (Russian Federation); Lisitsyna, L.A. [Tomsk State University of Architecture and Building, Soljanoj Street, 2, Tomsk (Russian Federation); Andryuschenko, L.A.; Yakubovskaya, A.G. [Institute for Scintillation Materials, Lenin Avenue, 60, Kharkov 61001 (Ukraine); Vovk, O.M. [Institute for Single Crystals, Lenin Avenue 60, 61001 Kharkiv (Ukraine)

    2014-09-15

    We investigated pulsed photoluminescence and pulsed cathodoluminescence in ZnWO{sub 4} crystals and composite materials based on dispersed powders of zinc tungstate in the polymer matrix. It is shown that the size of crystal particles affects the luminescence decay time in excitation by electron and laser radiation. The decay time obtained for the composite material with nanoparticles 25 nm and 100 nm in size is equal to 5 µs and 7 µs, respectively. Relative values of the light yield of composite containing zinc tungstate crystals in the form of rods are found to be larger in comparison with crystallites in the form of grains. The mechanisms of luminescence recombination in laser and electron excitation are discussed. - Highlights: • Pulsed photoluminescence and pulsed cathodoluminescence spectra and decay kinetics of nano- and microcrystals of zinc tungstate in the organosilicic matrix compared to a single crystal were studied. • The luminescence decay kinetics and life-time of the excited state depend on the size of particles in the composite materials and on the type of excitation. • The probability of excitation of luminescence centers responsible for the band at 490 nm is higher which is apparently due to the larger capture cross-section and quantum yield.

  19. Visible luminescence in polyaniline/(gold nanoparticle) composites

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Renata F. S. [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil); Andrade, Cesar A. S. [Universidade Federal de Pernambuco, Departamento de Bioquimica (Brazil); Santos, Clecio G. dos [Instituto de Educacao, Ciencia e Tecnologia de Pernambuco (Brazil); Melo, Celso P. de, E-mail: celso@df.ufpe.br [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil)

    2013-01-15

    We describe the use of solution chemistry methods to prepare polyaniline/(gold nanoparticles)-PANI/AuNPs-composites as colloidal particles that exhibit an intense green fluorescence after excitation in the ultraviolet region. Measurements of the relative fluorescence quantum yield indicate that the intensity of the observed luminescence of these nanocomposites is a few orders of magnitude higher than the corresponding fluorescence of either the isolated polymer or the pure AuNPs. Hence, cooperative effects between the conducting polymer chains and the metallic particles must dominate the emission behavior of these materials. Transmission electron microscopy reveals the existence of metal nanoparticle aggregates with sizes in the 2-3 nm range dispersed in the polymer matrix. By implementing an experimental planning, we have been able to change the preparation parameters so as to vary in a controlled manner the intensity and the profile of the luminescence spectrum as well as the size and aggregation characteristics of the colloidal particles. We also show that when the pH of the medium is varied, the dielectric properties (such as the degree of conductivity) of the PANI/AuNPs colloidal solutions and the intensity of their luminescence change in a consistent manner. Due to the polycation nature of the doped PANI chains, we suggest that these composites may find interesting applications as fluorescent markers of biologic molecules.

  20. Visible luminescence in polyaniline/(gold nanoparticle) composites

    Science.gov (United States)

    Santos, Renata F. S.; Andrade, Cesar A. S.; dos Santos, Clecio G.; de Melo, Celso P.

    2013-01-01

    We describe the use of solution chemistry methods to prepare polyaniline/(gold nanoparticles)—PANI/AuNPs—composites as colloidal particles that exhibit an intense green fluorescence after excitation in the ultraviolet region. Measurements of the relative fluorescence quantum yield indicate that the intensity of the observed luminescence of these nanocomposites is a few orders of magnitude higher than the corresponding fluorescence of either the isolated polymer or the pure AuNPs. Hence, cooperative effects between the conducting polymer chains and the metallic particles must dominate the emission behavior of these materials. Transmission electron microscopy reveals the existence of metal nanoparticle aggregates with sizes in the 2-3 nm range dispersed in the polymer matrix. By implementing an experimental planning, we have been able to change the preparation parameters so as to vary in a controlled manner the intensity and the profile of the luminescence spectrum as well as the size and aggregation characteristics of the colloidal particles. We also show that when the pH of the medium is varied, the dielectric properties (such as the degree of conductivity) of the PANI/AuNPs colloidal solutions and the intensity of their luminescence change in a consistent manner. Due to the polycation nature of the doped PANI chains, we suggest that these composites may find interesting applications as fluorescent markers of biologic molecules.

  1. Ratiometric fluorescent nanosensors for selective detecting cysteine with upconversion luminescence.

    Science.gov (United States)

    Guan, Yunlong; Qu, Songnan; Li, Bin; Zhang, Liming; Ma, Heping; Zhang, Ligong

    2016-03-15

    Fluorescent sensors based on upconversion (UC) luminescence have been considered as a promising strategy to detect bio-analyte due to their advantages in deep penetration, minimum autofluorescence, and ratiometric fluorescent output. A prototype of nanosensors combined with mesoporous silica coated upconversion nanoparticles (UCNPs) and a fluorescein-based fluorescent probe loaded in pores was therefore designed to detect cysteine (Cys). The silica shell provided loading space for the probe and enabled the nanosensors to disperse in water. In the presence of Cys, the fluorescent probe was transformed into 5(6)-carboxyfluorescein with an emission band centering at 518 nm which was secondarily excited by the light at around 475 nm from NaYF4:Yb(3+), Tm(3+) UCNPs driven by 980 nm near-infrared (NIR) laser. The intensity ratio between green and blue luminescence (I518/I475) grew exponentially with increasing concentrations of Cys over a range of 20-200 μmolL(-1). The response of the nanosensors towards Cys was recognizable with naked eyes by luminescence color change. Evidences suggest that these nanosensors are capable of sensing Cys in aqueous solution and distinguishing Cys from homocysteine (Hcy) with kinetically-controlled selectivity. The system was further employed to detect Cys in human serum and the result was in agreement with it tested by high performance liquid chromatography with acceptable recovery. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Lanthanide-Functionalized Metal-Organic Framework Hybrid Systems To Create Multiple Luminescent Centers for Chemical Sensing.

    Science.gov (United States)

    Yan, Bing

    2017-11-21

    Metal-organic frameworks (MOFs) possess an important advantage over other candidate classes for chemosensory materials because of their exceptional structural tunability and properties. Luminescent sensing using MOFs is a simple, intuitive, and convenient method to recognize species, but the method has limitations, such as insufficient chemical selectivity and signal loss. MOFs contain versatile building blocks (linkers or ligands) with special chemical reactivity, and postsynthetic modification (PSM) provides an opportunity to exploit and expand their unique properties. The linkers in most MOFs contain aromatic subunits that can readily display luminescence after ultraviolet or visible (typically blue) excitation, and this is the main luminescent nature of most MOFs. The introduction of photoactive lanthanide ions (Ln 3+ ) into the MOF hosts may produce new luminescent signals at different positions from that of the MOF linker, but this depends on the intramolecular energy transfer (antenna effect) from the MOF (linkers) to the Ln 3+ ions. Controlling the Ln 3+ content in MOF hybrids may create multiple luminescent centers. The nature of the unique luminescent centers may cause different responses to sensing species (i.e., ratiometric sensing), which may provide a new opportunity for luminescence research with applications to chemical sensing. In this Account, recent research progress on using lanthanide-functionalized MOF hybrid materials to create multiple luminescent centers for chemical sensing is described. Here we propose a general strategy to functionalize MOF hosts with lanthanide ions, compounds, or other luminescent species (organic dyes or carbon dots) and to assemble types of photofunctional hybrid systems based on lanthanide-functionalized MOFs. Five main methods were used to functionalize the MOFs and assemble the hybrid materials: in situ composition, ionic doping, ionic exchange, covalent PSM, and coordinated PSM. Through the lanthanide

  3. A portable luminescence dating instrument

    DEFF Research Database (Denmark)

    Kook, M.H.; Murray, A.S.; Lapp, Torben

    2011-01-01

    We describe a portable luminescence reader suitable for use in remote localities in the field. The instrument weighs about 8kg and is based around a 30mm bialkali photomultiplier detecting signals through a glass filter centered on 340nm. Stimulation is by 470nm blue LEDs (24W in total) operating...

  4. Advances in luminescence instrument systems

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Bulur, E.; Duller, G.A.T.

    2000-01-01

    We report on recent advances in the development of luminescence measurement systems and techniques at Riso. These include: (1) optical stimulation units based on new-generation powerful blue light (470 nm) emitting diodes providing up to 28 mW/cm(2) for OSL measurements; (2) an infrared (830 nm...

  5. Thermally stimulated luminescence and photoluminescence ...

    Indian Academy of Sciences (India)

    Thermally stimulated luminescence (TSL) investigations of SrBPO5:Eu3+ and SrBPO5:Eu2+ phosphors were carried out in the temperature range of 300–650 K. In order to characterize the phosphors, X-ray diffraction and photoluminescence (PL) techniques were used. The emission spectrum of air heated SrBPO5:Eu3+ ...

  6. Controlling plasmon-enhanced luminescence

    NARCIS (Netherlands)

    Mertens, H.

    2007-01-01

    Plasmons are collective oscillations of the free electrons in a metal or an ionized gas. Plasmons dominate the optical properties of noble-metal nanoparticles, which enables a variety of applications. This thesis focuses on plasmon-enhanced luminescence of silicon quantum dots (Si QDs) and optically

  7. Photoluminescence, thermally stimulated luminescence and ...

    Indian Academy of Sciences (India)

    Photoluminescence, thermally stimulated luminescence and electron paramagnetic resonance studies of U. 6+ doped BaSO4. M K BHIDE, T K SESHAGIRI. ∗. , SASHIKALA OJHA† and S V GODBOLE. Radiochemistry Division, †Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.

  8. Origin of luminescence quenching in structures containing CdSe/ZnSe quantum dots with a few Mn2 + ions

    Science.gov (United States)

    Oreszczuk, K.; Goryca, M.; Pacuski, W.; Smoleński, T.; Nawrocki, M.; Kossacki, P.

    2017-11-01

    We present a detailed spectroscopic study of photoluminescence quenching in epitaxial structures containing CdSe/ZnSe quantum dots doped with low concentration of Mn2 + ions. Our time-resolved and time-integrated experiments reveal the origin of the quenching observed in macro-photoluminescence studies of ensembles of such dots. We show that incorporation of even a few ions to an individual dot does not quench its luminescence effectively, although some fingerprints of expected spin-dependent quenching are visible. At the same time, the presence of Mn2 + ions in the sample significantly affects the luminescence intensity of the wetting layer, resulting in a quenching of the global luminescence from studied structure. On the other hand, the luminescence decay dynamics are found to be independent of the presence of Mn2 + ions, which suggests that the observed quenching occurs for the excited excitonic states.

  9. Luminescent properties of ytterbium-doped ternary lanthanum chloride

    Energy Technology Data Exchange (ETDEWEB)

    Kaminska, A., E-mail: kaminska@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Cybinska, J. [Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland); Zhydachevskii, Ya. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Lviv Polytechnic National University, 12 Bandera, Lviv 79646 (Ukraine); Sybilski, P. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Meyer, G. [Department of Chemistry, University of Cologne, Greinstrasse 6, D-50939 Koeln (Germany); Suchocki, A. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Institute of Physics, University of Bydgoszcz, Weyssenhoffa 11, 85-072, Bydgoszcz (Poland)

    2011-07-28

    Highlights: > Ytterbium-doped ternary lanthanum chloride as a promising light-emitting material. > The luminescence properties of K{sub 2}LaCl{sub 5}:Yb{sup 3+} powders with different Yb concentration. > Very good temperature stability of the powders for higher Yb concentration. - Abstract: Studies of the absorption and temperature dependence of photoluminescence spectra and luminescence decay times of the intra-shell f-f transitions ({sup 2}F{sub 5/2} {r_reversible} {sup 2}F{sub 7/2}) of Yb{sup 3+} ions in K{sub 2}LaCl{sub 5}:Yb{sup 3+} powders with 5, 10, 15 and 25% of ytterbium are presented. The spectroscopic properties of the powders with different ytterbium content are compared. Experiments were performed at the temperatures from 25 to 300 K. The strong emission around 982 nm has been observed under direct excitation of the luminescence center with 960 nm line of continuous wave Ti:sapphire laser pumped by Ar-ion laser. The temperature quenching effect of the luminescence was rather week, especially in the samples with higher concentration of ytterbium (15 and 25%). Additionally the probability of the f-f radiative transitions of the Yb{sup 3+} ions in these powders was almost temperature independent for more heavily doped samples (with 15 and 25% of Yb) and only weakly temperature dependent for less doped samples (with 5 and 10% of Yb). These results reveal high thermal stability of the optical properties of the examined powders.

  10. Role of the electronic excited-state hydrogen bonding in the nitro-explosives detection by [Zn2(oba)2(bpy)

    Science.gov (United States)

    Wang, Peipei; Song, Xuedan; Zhao, Zhengyan; Liu, Lei; Mu, Wensheng; Hao, Ce

    2016-09-01

    This paper investigates the luminescent properties of luminescent metal-organic framework (LMOF) [Zn2(oba)2(bpy)], and its selectivity for the detection of nitro-explosives via fluorescence quenching, using the density functional and time-dependent density functional theories. The luminescent mechanism of the LMOF follows the electron transfer from ligand to ZnO quantum dot. The hydrogen bondings formed between LMOF and electron-withdrawing nitro-explosives as well as electron-donating aromatic compounds have different influences on the luminescent mechanism of the LMOF. The hydrogen bonding in the excited state was investigated to display the relationship between hydrogen bonding and fluorescence.

  11. General synthesis route to fabricate uniform upconversion luminescent gadolinium oxide hollow spheres.

    Science.gov (United States)

    Jia, Guang; Zhang, Cuimiao; Ding, Shiwen; Wang, Liyong

    2011-08-01

    Uniform upconversion luminescent gadolinium oxide hollow spheres were successfully synthesized via a homogeneous precipitation method with carbon spheres as template followed by a calcination process. During the annealing process, the carbon spheres template can be effectively removed and the amorphous precursor has converted to crystalline Gd2O3, which can be confirmed by the XRD and TG-DSC analysis. SEM and TEM images indicate that the Gd2O3 hollow spheres with diameters of 300-400 nm are uniform in size and distribution. The rare earth activator ions Ln3+-doped Gd2O3 hollow spheres exhibit intense upconversion luminescence with different colors under 980 nm light excitation, which may find potential applications in the fields such as drug delivery or biological labeling. Moreover, the upconversion luminescent mechanisms of the hollow spherical phosphors were investigated in detail.

  12. A mechanism of the anti-Stokes luminescence of a dye-sensitized silver halide emulsion

    Science.gov (United States)

    Tyurin, A. V.; Churashov, V. P.; Zhukov, S. A.; Pavlova, O. V.

    2008-02-01

    A two-photon stepwise mechanism of the low-temperature anti-Stokes luminescence of a sensitized AgBrI emulsion, caused by photoexcitation of dye aggregates, is proved experimentally. According to this mechanism, the photoexcitation energy is transferred from the dye to the AgHal microcrystal through silver cluster centers. It is found that the luminescence with the maximum at λ ≈ 750 nm is caused by the recombination of an electron localized at the silver cluster with a free hole in the valence band of the AgHal microcrystal. The migration of an electron from a silver cluster to a iodine pair center with a captured hole creates a nonradiative recombination channel, which is responsible for the flare buildup of the green anti-Stokes luminescence upon excitation of dye aggregates.

  13. Study on the preparation of ZnGa2O4 phosphor and its luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, H.; Park, H. [Korea Research Institute of Chemical Technology, Taejon (Korea, Republic of)

    1997-08-25

    The ZnGa2O4 phosphors were prepared using the solid state reaction method to investigate their photoluminescence characteristics and luminescence mechanism. Under 254 nm excitation, the ZnGa2O4 phosphor exhibited a broad-band blue luminescence with an emission spectral peak at 450 nm. The reduction treatment of ZnGa2O4 phosphors in partial hydrogen atmosphere showed a tremendous increase of emission intensity of all phosphors. On the other hand, Mn{sup 2+}-doped ZnGa2O4 phosphor exhibited a strong narrow-band green luminescence with an emission spectral peak at 504 nm, and showed a maximum emission intensity at the Mn{sup 2+} concentration of 0.006 mol %. 12 refs., 7 figs.

  14. The influence of energy migration on luminescence kinetics parameters in upconversion nanoparticles.

    Science.gov (United States)

    Alyatkin, Sergey; Asharchuk, Ilya; Khaydukov, Kirill; Nechaev, Andrey; Lebedev, Oleg; Vainer, Yuri; Semchishen, Vladimir; Khaydukov, Evgeny

    2017-01-20

    The mechanism of upconversion at the nanoscale is still under discussion. In this paper, we report on the experimental results of anti-Stokes luminescence kinetics in the upconversion nanoparticles of β-NaYF4: 20%Yb3+; 0.6%Tm3+. The parameters of the luminescence kinetics were found to be unambiguously dependent on the number of excitation quanta n, which are necessary for certain transitions between the energy states of thulium ions. The observed correlation has been explained by means of the long-lasting energy migration between the ytterbium ions. The spread in time between the luminescent maxima of the corresponding thulium transitions not only shows the nonlinear character of upconversion, but also reveals the time scale of energy migration as well. From these, we derive that the conventional Förster formalism applied to the estimation of energy transfer efficiency in UCNP-fluorophore pairs can provide misleading results.

  15. Pump-dependent luminescence in the Ag nanoparticles doped by Erbium

    Energy Technology Data Exchange (ETDEWEB)

    Ebothe, J. [Laboratoire de Microscopie et d' Etude de Nanostructures - E.A.N3799, Boite Postale 138, 21 rue Clement Ader, F-51685m Reims (France); Ozga, K. [Institute of Biology and Biophysics, Technical University of Czestochowa, Al. Armii Krajowej 36 B, Czestochowa (Poland); Ali Umar, A. [International Innovation Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8520 (Japan); Oyama, M. [International Innovation Center, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8520 (Japan); Kityk, I.V. [Institute of Physics, J. Dlugosz University, Czestochowa (Poland)]. E-mail: i.kityk@ajd.czest.pl

    2006-11-30

    A substantial spectral shift of the UV-laser induced luminescence in the Ag nanoparticles (NP) doped by Er{sup 3+} ions attached to ITO substrates was observed at T = 4.2 K. We have established high energy spectral shift of principal luminescent maxima (from wavelength equal to about 1.45 up to 1.15 {mu}m) with increasing of the pumping nanosecond nitrogen laser power density up to 1.1 GW/cm{sup 2} operating at {lambda} = 337 nm. With increasing Erbium content with respect to Ag the spectral shift and spectral line broadening increase. It may be caused by specific features of trapping level occupation kinetics on interfaces NP/ITO substrate. The observed process is fully reversible. The luminescence is observed only during excitation by the 337 nm laser pulses and is absent for laser pulses operating at other wavelengths (like excimer laser at 218 nm and nitrogen laser at 371 nm)

  16. Enhanced quantum cutting luminescence by Au nanorods through improving radiative transition rate

    Science.gov (United States)

    Zheng, Biao; Lin, Lin; Feng, Zhuohong; Huang, Lili; Zhuang, Luoqing; Wang, Zhezhe; Zheng, Zhiqiang

    2017-11-01

    Quantum cutting (QC) phosphor β-NaYF4:Tb3+, Yb3+ nanoparticles (NPs) are decorated with Au nanorods (NRs). By tailoring Au NRs longitudinal plasmon resonance to match the emission wavelength of Yb3+ ion, plasmon-enhanced near-infrared (NIR) QC luminescence is achieved through improving Yb3+ ion's radiative transition rate. The decay curves of Yb3+ ion in β-NaYF4:Tb3+, Yb3+ NPs decorated with Au NRs further confirm the improvement of radiative transition rate. The influence of Au NRs concentration on QC luminescence is also investigated, and the results show that the optimal concentration of Au NRs is 0.12% with the maximum enhancement factor about 3. Our study may not only path the way to achieve simultaneous excitation and emission enhancement of QC luminescence, but also provide a potential application as QC layer to silicon-based solar cells.

  17. Europium incorporated in silica matrix obtained by sol-gel: luminescent materials

    Directory of Open Access Journals (Sweden)

    Nassar Eduardo José

    2003-01-01

    Full Text Available In this work we report some aspects of the chemistry involved in the preparation of modified silicon oxide by the sol-gel process. Europium III compounds were used as luminescent probe. An organic-inorganic hybrid was obtained by hydrolysis of tetraethylorthosilicate (TEOS and 3-aminopropyltriethoxysilane (APTS. The Eu III compounds were added in different ways. In the first, silica was prepared in the presence of Eu III, and in the second, Eu III was added on the silica surface. These materials were studied by luminescence, infrared spectroscopy and termogravimetric analysis. The results obtained for the hybrid material show different behavior for Eu III emission, which could be excited by the antenna effect and the influence of the surrounding in the luminescence quenching. The thermogravimetric data present different mass loss in samples to range temperature 50 - 150 °C. Thermogravimetric and infrared spectra showed that inorganic polymers incorporated the organic part.

  18. The influence of energy migration on luminescence kinetics parameters in upconversion nanoparticles

    Science.gov (United States)

    Alyatkin, Sergey; Asharchuk, Ilya; Khaydukov, Kirill; Nechaev, Andrey; Lebedev, Oleg; Vainer, Yuri; Semchishen, Vladimir; Khaydukov, Evgeny

    2017-01-01

    The mechanism of upconversion at the nanoscale is still under discussion. In this paper, we report on the experimental results of anti-Stokes luminescence kinetics in the upconversion nanoparticles of β-NaYF4: 20%Yb3+; 0.6%Tm3+. The parameters of the luminescence kinetics were found to be unambiguously dependent on the number of excitation quanta n, which are necessary for certain transitions between the energy states of thulium ions. The observed correlation has been explained by means of the long-lasting energy migration between the ytterbium ions. The spread in time between the luminescent maxima of the corresponding thulium transitions not only shows the nonlinear character of upconversion, but also reveals the time scale of energy migration as well. From these, we derive that the conventional Förster formalism applied to the estimation of energy transfer efficiency in UCNP-fluorophore pairs can provide misleading results.

  19. Nanoscale coordination polymers exhibiting luminescence properties and NMR relaxivity

    Science.gov (United States)

    Chelebaeva, Elena; Larionova, Joulia; Guari, Yannick; Ferreira, Rute A. S.; Carlos, Luis D.; Trifonov, Alexander A.; Kalaivani, Thangavel; Lascialfari, Alessandro; Guérin, Christian; Molvinger, Karine; Datas, Lucien; Maynadier, Marie; Gary-Bobo, Magali; Garcia, Marcel

    2011-03-01

    This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd-DTPA® or Omniscan® indicating that our samples may potentially be considered as a positive contrast agent for MRI. The in vitro studies performed on these nanoparticles show that they maybe internalized into human cancer and normal cells and well detected by fluorescence at the single cell level. They present high stability even at low pH and lack of cytotoxicity both in human cancer and normal cells.This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd

  20. Origin of the visible light induced persistent luminescence of Cr3+-doped zinc gallate

    Science.gov (United States)

    Gourier, Didier; Bessière, Aurélie; Sharma, Suchinder. K.; Binet, Laurent; Viana, Bruno; Basavaraju, Neelima; Priolkar, Kaustubh R.

    2014-07-01

    ZnGa2O4:Cr3+ (ZGO:Cr) is a very bright persistent phosphor able to emit a near infrared light for hours following a UV (band to band excitation) or visible (Cr3 excitation) illumination. As such it serves as an outstanding biomarker for in vivo imaging. Persistent luminescence, due to trapping of electrons/holes at point defects, is studied here on a series of ZGO:Cr spinel compounds where the introduction of defects is controlled by varying the Zn/(Ga+Cr) nominal ratio during synthesis. Simulation of Electron Paramagnetic Resonance spectra revealed up to six types of Cr3+ ions with different neighboring defects and correlated to four emission lines in low temperature photoluminescence spectroscopy. Of particular importance, three EPR signals were attributed to Cr3+ with a pair of neighboring ZnGa' and GaZn0° antisite defects. They were identified to the emission line N2 that plays a key role in the persistent luminescence mechanism for both storage of visible excitation and persistent luminescence emission. A model is proposed whereby the local electric field at Cr3+ created by the two neighboring antisite defects triggers the electron-hole separation and trapping upon excitation of Cr3+. The process is equivalent to a photoinduced electron transfer from a donor (here ZnGa') to an acceptor (here GaZn0°) observed in some molecular systems.

  1. Luminescence properties of organic–inorganic layered perovskite-type compounds under vacuum ultraviolet irradiation

    Science.gov (United States)

    Kawano, Naoki; Koshimizu, Masanori; Okada, Go; Fujimoto, Yutaka; Kawaguchi, Noriaki; Yanagida, Takayuki; Asai, Keisuke

    2018-02-01

    We investigated the luminescence properties of organic–inorganic layered perovskite-type compounds under vacuum ultraviolet irradiation. A crystal of (C6H5C2H4NH3)2PbBr4 was fabricated by the poor-solvent diffusion method. Exciton emissions from the inorganic layer were observed at 410 nm under ultraviolet irradiation (excitation wavelengths: 180 and 300 nm). The rise time behavior observed in the luminescence decay curve showed no difference among the excitation wavelengths of 60–300 nm. In addition, no excitation peak of benzene such as an intense peak at 180 nm (1A1g → 1E1u) in the vacuum ultraviolet region was observed in the excitation spectra measured while monitoring the exciton emissions from the inorganic layer. These results indicate that the effect of energy transfer from the organic layer to the inorganic layer has negligible contribution to the luminescence properties of organic–inorganic layered perovskite-type compounds.

  2. Multispectral upconversion luminescence intensity ratios for ascertaining the tissue imaging depth

    Science.gov (United States)

    Liu, Kai; Wang, Yu; Kong, Xianggui; Liu, Xiaomin; Zhang, Youlin; Tu, Langping; Ding, Yadan; Aalders, Maurice C. G.; Buma, Wybren Jan; Zhang, Hong

    2014-07-01

    Upconversion nanoparticles (UCNPs) have in recent years emerged as excellent contrast agents for in vivo luminescence imaging of deep tissues. But information abstracted from these images is in most cases restricted to 2-dimensions, without the depth information. In this work, a simple method has been developed to accurately ascertain the tissue imaging depth based on the relative luminescence intensity ratio of multispectral NaYF4:Yb3+,Er3+ UCNPs. A theoretical mode was set up, where the parameters in the quantitative relation between the relative intensities of the upconversion luminescence spectra and the depth of the UCNPs were determined using tissue mimicking liquid phantoms. The 540 nm and 650 nm luminescence intensity ratios (G/R ratio) of NaYF4:Yb3+,Er3+ UCNPs were monitored following excitation path (Ex mode) and emission path (Em mode) schemes, respectively. The model was validated by embedding NaYF4:Yb3+,Er3+ UCNPs in layered pork muscles, which demonstrated a very high accuracy of measurement in the thickness up to centimeter. This approach shall promote significantly the power of nanotechnology in medical optical imaging by expanding the imaging information from 2-dimensional to real 3-dimensional.Upconversion nanoparticles (UCNPs) have in recent years emerged as excellent contrast agents for in vivo luminescence imaging of deep tissues. But information abstracted from these images is in most cases restricted to 2-dimensions, without the depth information. In this work, a simple method has been developed to accurately ascertain the tissue imaging depth based on the relative luminescence intensity ratio of multispectral NaYF4:Yb3+,Er3+ UCNPs. A theoretical mode was set up, where the parameters in the quantitative relation between the relative intensities of the upconversion luminescence spectra and the depth of the UCNPs were determined using tissue mimicking liquid phantoms. The 540 nm and 650 nm luminescence intensity ratios (G/R ratio) of NaYF4:Yb3

  3. Luminescence of a Transition Metal Complex Inside a Metamaterial Nanocavity.

    Science.gov (United States)

    Connell, Timothy U; Earl, Stuart K; Ng, Charlene; Roberts, Ann; Davis, Timothy J; White, Jonathan M; Polyzos, Anastasios; Gómez, Daniel E

    2017-08-01

    Modification of the local density of optical states using metallic nanostructures leads to enhancement in the number of emitted quanta and photocatalytic turnover of luminescent materials. In this work, the fabrication of a metamaterial is presented that consists of a nanowire separated from a metallic mirror by a polymer thin film doped with a luminescent organometallic iridium(III) complex. The large spin-orbit coupling of the heavy metal atom results in an excited state with significant magnetic-dipole character. The nanostructured architecture supports two distinct optical modes and their assignment achieved with the assistance of numerical simulations. The simulations show that one mode is characterized by strong confinement of the electric field and the other by strong confinement of the magnetic field. These modes elicit drastic changes in the emitter's photophysical properties, including dominant nanocavity-derived modes observable in the emission spectra along with significant increases in emission intensity and the total decay rate. A combination of simulations and momentum-resolved spectroscopy helps explain the mechanism of the different interactions of each optical mode supported by the metamaterial with the excited state of the emitter. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Measurement of the time-resolved spectrum of photoelectrons from ZnS:Mn, Cu luminescent material

    CERN Document Server

    Dong Guo Yi; Wei Zh; Yang Shao Peng; Fu Guang Sheng

    2003-01-01

    The process of decay of photoelectrons in the conduction band of ZnS:Mn, Cu luminescent materials after excitation with a short-pulse laser has been investigated in this paper by means of measurements made using the microwave absorption dielectric spectrum detection technique. Exponential decay processes were observed for the electrons in the conduction band and the shallow-trapped electrons; the lifetimes of the electrons were found to be 1177 and 1703 ns, respectively. The processes of decay of the luminescence from ZnS:Mn, Cu were investigated and exponential decay processes were found for blue Cu sup + , green Cu sup + and Mn sup 2 sup + luminescent centres with lifetimes of the excited state of 139, 140 and 680 mu s, respectively.

  5. Study on preparation and characterization of MOF based lanthanide doped luminescent coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Binh, Nguyen Thanh; Tien, Dinh Manh; Giang, Lam Thi Kieu; Khuyen, Hoang Thi; Huong, Nguyen Thanh; Huong, Tran Thu; Lam, Tran Dai, E-mail: lamtd@ims.vast.ac.vn

    2014-02-14

    Coordination polymers (metal–organic frameworks or MOFs) offer the opportunity for fine-tuning the luminescence behavior because of the possibility to entrap in the network pores molecules that can influence the lanthanide (Ln) emission. In this study, Zn (II) and polycarboxylate based MOFs were first pre-formed by solvothermal method, then considered as host-matrix for in situ doping of low-input concentration of Eu{sup 3+} and Tb{sup 3+} (two most commonly used lanthanides in life science assays), and afterwards lanthanide doped luminescent materials were synthesized. Different characterizations (X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS)) were carried out to confirm accordingly MOF's crystallinity, the structure and chemical composition. The study on luminescent properties of the material has revealed an efficient energy transfer from the ligand excited states to the Eu{sup 3+} and Tb{sup 3+} f-excited states. With quite low input concentrations (8–15%) of doped rare earth ions, these complexes displayed intense emissions at room temperature and proved to be good candidates for red and green emitter luminescent materials. Generally, this design concept can be extended for the preparation of other rare earth coordination polymers. - Highlights: • Synthesis of luminescent materials MOF-5/RE (RE = Eu, Tb) by solvothermal method with in situ doping of Eu{sup 3+} and Tb{sup 3+}. • MOF-5/RE with ordered structure gives strong luminescence spectra. • The design concept can be extended for the preparation of other rare earth coordination polymers.

  6. Phasor plots of luminescence decay functions

    Energy Technology Data Exchange (ETDEWEB)

    Berberan-Santos, Mário N., E-mail: berberan@tecnico.ulisboa.pt

    2015-03-01

    Highlights: • First complete study of the phasor plots of a sum of two exponentials (2E). • The existence of a 2E limiting curve (outer boundary) is demonstrated. • A generalization of the lever rule is presented. • Virtual phasor concept. • Study of several decay laws displaying a diversity of patterns. - Abstract: Luminescence decay functions describe the time dependence of the intensity of radiation emitted by electronically excited species. Decay phasor plots (plots of the Fourier sine transform vs. the Fourier cosine transform, for one or several angular frequencies) are being increasingly used in fluorescence, namely in lifetime imaging microscopy (FLIM). In this work, a detailed study of the sum of two exponentials decay function is carried out revealing that sub-exponential, super-exponential and unimodal decays have different phasor signatures. A generalization of the lever rule is obtained, and the existence of an outermost phasor curve corresponding to intermediate-like decays is demonstrated. A study of the behavior of more complex decay functions (sum of three exponentials, stretched and compressed exponentials, phosphorescence with reabsorption and triplet–triplet annihilation, fluorescence with quantum beats) allows concluding that a rich diversity of phasor plot patterns exists. In particular, super-exponential decays can present complex shapes, spiraling at high frequencies. The concept of virtual phasor is also introduced.

  7. LASER PHYSICS: Determination of the absolute quantum efficiency of the luminescence of Xe2Cl* in Cl2-Xe mixtures

    Science.gov (United States)

    Zuev, V. S.; Kanaev, A. V.; Mikheev, L. D.

    1987-07-01

    The composition dependences of the absolute quantum efficiency of the luminescence of the Xe2Cl* trimer, emitting in the blue-green part of the spectrum, were determined for Cl2-Xe mixtures excited at the wavelength of 137.2 nm. A high (up to 100%) efficiency of trimer formation observed under optical excitation conditions makes media of this kind promising for laser applications.

  8. Synthesis and luminescent properties of a novel green-emitting Tb (Ⅲ) complex based on amino-modified fluorine silicone oil and isophorone diisocyanate

    Science.gov (United States)

    Hao, Haixia; Chu, Yang; Yu, Zhenjiang; Xie, Hongde; Seo, Hyo Jin

    2017-10-01

    The novel luminescent polymer-rare earth complexes, denoted as (PFSi-IPDI)-Tb(Ⅲ)-Phen, have been successfully synthesized and can be made into flexible films. Amino-modified fluorine silicone oil-isophorone diisocyanate (PFSi-IPDI) was used as the host macromolecular ligand, and 1, 10-Phenanthroline (Phen) as the secondary small-molecular co-ligand. The luminescent lanthanide complexes were characterized by fourier transform infrared (FITR), scanning electron microscope (SEM), thermogravimetric analysis (TGA). The luminescent properties were investigated through photoluminescence excitation (PLE) and emission (PL) spectroscopy. FTIR analysis verifies the successful preparation and integration of PFSi-IPDI to Tb3+. The comparatively uniform morphological structure can be observed in the images of SEM. The polymer-rare earth complexes display the typical luminescence emission peaks under the excitation wavelength of 330 nm. From the decay curve, the short lifetime (about 0.89 ms) is observed for (PFSi-IPDI)-Tb(Ⅲ)-Phen (0.6 mol/L). Moreover, these luminescent polymer-rare earth complexes possess superior thermal stability (T5 > 195 °C). All the interesting results suggest the potential application of the luminescent polymer-rare earth complexes in green-emitting luminescent materials under high temperature.

  9. Luminescent Solar Concentrators – a low cost photovoltaics alternative

    NARCIS (Netherlands)

    Sark, W.G.J.H.M. van

    2013-01-01

    The development and current status of luminescent solar concentrators is reviewed. These solar concentrators generally consist of transparent polymer sheets doped with luminescent species; presently mainly organic dye molecules are used as luminescent species, however semiconductor nanocrystals

  10. Effect of calcinations temperature on the luminescence intensity and fluorescent lifetime of Tb3+-doped hydroxyapatite (Tb-HA) nanocrystallines

    National Research Council Canada - National Science Library

    Hairong Yin; Yanxiao Li; Jianguang Bai; Mingxin Ma; Jing Liu

    2017-01-01

    ...+ ions were observed in emission spectra of 6 mol.% Tb-HA under 378 nm excitation. The luminescent intensity of Tb-HA, which showed the fluorescence quenching, firstly enhanced and then decreased at 700 °C...

  11. Fluorometer with a quartz-rod waveguide-integrating sphere configuration to measure evanescent-field luminescence

    Science.gov (United States)

    A fluorometer was designed to measure evanescent-field luminescence. A quartz-rod waveguide (d = 2 mm) was installed coaxally inside a cylindrical flow-through cell (id = 2.3 mm, od = 6.3 mm, l = 116 mm). An excitation beam from a UV LED or a miniature xenon flashlamp was focused by a ball lens and ...

  12. Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors.

    Science.gov (United States)

    Coutino-Gonzalez, Eduardo; Baekelant, Wouter; Dieu, Bjorn; Roeffaers, Maarten B J; Hofkens, Johan

    2016-11-15

    Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film.

  13. Circularly Polarized Luminescence in Enantiopure Europium and Terbium Complexes with Modular, All-Oxygen Donor Ligands

    Science.gov (United States)

    Seitz, Michael; Do, King; Ingram, Andrew J.; Moore, Evan G.; Muller, Gilles; Raymond, Kenneth N.

    2009-01-01

    Abstract: Circulaly polarized luminescence from terbium(III) complexed and excited by chiral antenna ligands gives strong emission The modular synthesis of three new octadentate, enantiopure ligands are reported - one with the bidentate chelating unit 2-hydroxyisophthalamide (IAM) and two with 1-hydroxy-2-pyridinone (1,2-HOPO) units. A new design principle is introduced for the chiral, non-racemic hexamines which constitute the central backbones for the presented class of ligands. The terbium(III) complex of the IAM ligand, as well as the europium(III) complexes of the 1,2-HOPO ligands are synthesized and characterized by various techniques (NMR, UV, CD, luminescence spectroscopy). All species exhibit excellent stability and moderate to high luminescence efficiency (quantum yields ΦEu = 0.05–0.08 and ΦTb = 0.30–0.57) in aqueous solution at physiological pH. Special focus is put onto the properties of the complexes in regard to circularly polarized luminescence (CPL). The maximum luminescence dissymmetry factors (glum) in aqueous solution are high with |glum|max = 0.08 – 0.40. Together with the very favorable general properties (good stability, high quantum yields, long lifetimes), the presented lanthanide complexes can be considered as good candidates for analytical probes based on CPL in biologically relevant environments. PMID:19639983

  14. Lanthanide Organic Framework Luminescent Thermometers.

    Science.gov (United States)

    Rocha, João; Brites, Carlos D S; Carlos, Luís D

    2016-10-10

    Metal-organic frameworks (MOFs) are excellent platforms for engineering luminescence properties as their building blocks, metal ions, linkers, and guest ions or molecules, are all potential sources of light emission. Temperature is one of the most important physical properties affecting the dynamics and viability of natural and engineered systems. Because the luminescence of certain lanthanide-bearing MOFs changes considerably with temperature, in the last few years, these materials have been explored as optical thermometers, especially in temperature sensing based on the intensity ratios of two separate electronic transitions. This review discusses the main concepts and ideas assisting the design of such ratiometric thermometers, and identifies the main challenges presented to this nascent field: develop nanothermometers for bio-applications and nanomedicine; understand the energy transfer mechanisms determining the thermal sensitivity; achieve effective primary thermometers; realize multifunctional nanothermometers; integrate Ln 3+ -based thermometers in commercial products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Modern luminescence spectroscopy of minerals and materials

    CERN Document Server

    Gaft, Michael; Panczer, Gerard

    2005-01-01

    Luminescence Spectroscopy of Minerals and Materials presents an overview of the general concepts in luminescence spectroscopy as well as experimental methods and their interpretation. Special emphasis is laid on the fluorescence lifetime and the determination of time-resolved spectra. This method enables the exposure of new luminescence in minerals previously hidden by more intensive centers. Specialists in the fields of solid state physics, chemistry and spectroscopy will find a wealth of new information in this unique book.

  16. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  17. Luminescent solar concentrators employing phycobilisomes

    Energy Technology Data Exchange (ETDEWEB)

    Mulder, Carlijn L.; Theogarajan, Luke; Currie, Michael; Mapel, Jonathan K.; Baldo, Marc A. [Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Vaughn, Michael; Willard, Paul; Bruce, Barry D. [Biochemistry, Cellular and Molecular Biology and Chemical and Biomolecular Engineering University of Tennessee at Knoxville 125 Austin Peay Bldg., Knoxville, TN 37996 (United States); Moss, Mark W.; McLain, Clifford E.; Morseman, John P. [Columbia Biosciences Corporation 6440 Suite D Dobbin Road, Columbia, MD 21045 (United States)

    2009-08-21

    Phycobilisome-based luminescent solar concentrators (LSCs) take advantage of the photosynthetic antenna complexes of red algae and cyanobacteria. The phycobilisomes are successfully stabilized in a solid-state LSC matrix with minimal loss of performance. Comparison of samples with intact and decoupled complexes indicates that energy transfer within intact phycobilisomes results in a reduction of re-absorption losses by {proportional_to}50%. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Stability of sulfate complexes of electronically excited uranyl

    Energy Technology Data Exchange (ETDEWEB)

    Ostakhov, S.S.; Kazakov, V.P.; Afonichev, D.D. [Inst. of Organic Chemistry, Ufa (Russian Federation)

    1995-11-01

    The complex formation of electronically excited uranyl ions with SO{sub 4}{sup 2-}anions in 0.1 M aqueous HClO{sub 4} has been studied by time-resolved luminescence spectroscopy. The stability constants of uranyl sulfate complexes (UO{sub 2}SO{sub 4}) (K=870 1 mol{sup -1}) and [UO{sub 2}(SO{sub 4}){sub 2}{sup 2-}](K=47000 1 mol{sup -1}) in excited state have been determined; they are more than an order of magnitude greater than those reported for complex formation of uranyl ions in the ground state. The complex formation of uranyl with sulfate ions is accompanied by the increase of the quantum yield of the uranyl lumenescence. The maxima of luminescence and absorption bands of uranyl ions are shifted with increasing the total concentration of SO{sub 4}{sup 2-} in solution, which supports the data obtained. The shift of the maxima of luminescence bands is observed at a sulfate concentration that is considerably lower than that causing the same shift of the maxima of the absorption bands. Such effect is consistent with the calculated stability constants of sulfate complexes of excited uranyl ions.

  19. Resonance-shifting luminescent solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel Christopher; Wiederrecht, Gary P.; Wasielewski, Michael R.

    2018-01-23

    An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

  20. Resonance-shifting luminescent solar concentrators

    Science.gov (United States)

    Giebink, Noel Christopher; Wiederrecht, Gary P; Wasielewski, Michael R

    2014-09-23

    An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

  1. Luminescent detection of hydrazine and hydrazine derivatives

    Science.gov (United States)

    Swager, Timothy M [Newton, MA; Thomas, III, Samuel W.

    2012-04-17

    The present invention generally relates to methods for modulating the optical properties of a luminescent polymer via interaction with a species (e.g., an analyte). In some cases, the present invention provides methods for determination of an analyte by monitoring a change in an optical signal of a luminescent polymer upon exposure to an analyte. Methods of the present invention may be useful for the vapor phase detection of analytes such as explosives and toxins. The present invention also provides methods for increasing the luminescence intensity of a polymer, such as a polymer that has been photobleached, by exposing the luminescent polymer to a species such as a reducing agent.

  2. Luminescent Organic Semiconducting Langmuir Monolayers.

    Science.gov (United States)

    Agina, Elena V; Mannanov, Artur A; Sizov, Alexey S; Vechter, Olga; Borshchev, Oleg V; Bakirov, Artem V; Shcherbina, Maxim A; Chvalun, Sergei N; Konstantinov, Vladislav G; Bruevich, Vladimir V; Kozlov, Oleg V; Pshenichnikov, Maxim S; Paraschuk, Dmitry Yu; Ponomarenko, Sergei A

    2017-05-31

    In recent years, monolayer organic field-effect devices such as transistors and sensors have demonstrated their high potential. In contrast, monolayer electroluminescent organic field-effect devices are still in their infancy. One of the key challenges here is to create an organic material that self-organizes in a monolayer and combines efficient charge transport with luminescence. Herein, we report a novel organosilicon derivative of oligothiophene-phenylene dimer D2-Und-PTTP-TMS (D2, tetramethyldisiloxane; Und, undecylenic spacer; P, 1,4-phenylene; T, 2,5-thiophene; TMS, trimethylsilyl) that meets these requirements. The self-assembled Langmuir monolayers of the dimer were investigated by steady-state and time-resolved photoluminescence spectroscopy, atomic force microscopy, X-ray reflectometry, and grazing-incidence X-ray diffraction, and their semiconducting properties were evaluated in organic field-effect transistors. We found that the best uniform, fully covered, highly ordered monolayers were semiconducting. Thus, the ordered two-dimensional (2D) packing of conjugated organic molecules in the semiconducting Langmuir monolayer is compatible with its high-yield luminescence, so that 2D molecular aggregation per se does not preclude highly luminescent properties. Our findings pave the way to the rational design of functional materials for monolayer organic light-emitting transistors and other optoelectronic devices.

  3. Photon Luminescence of the Moon

    Science.gov (United States)

    Wilson, T.L.; Lee, K.T.

    2009-01-01

    Luminescence is typically described as light emitted by objects at low temperatures, induced by chemical reactions, electrical energy, atomic interactions, or acoustical and mechanical stress. An example is photoluminescence created when photons (electromagnetic radiation) strike a substance and are absorbed, resulting in the emission of a resonant fluorescent or phosphorescent albedo. In planetary science, there exists X-ray fluorescence induced by sunlight absorbed by a regolith a property used to measure some of the chemical composition of the Moon s surface during the Apollo program. However, there exists an equally important phenomenon in planetary science which will be designated here as photon luminescence. It is not conventional photoluminescence because the incoming radiation that strikes the planetary surface is not photons but rather cosmic rays (CRs). Nevertheless, the result is the same: the generation of a photon albedo. In particular, Galactic CRs (GCRs) and solar energetic particles (SEPs) both induce a photon albedo that radiates from the surface of the Moon. Other particle albedos are generated as well, most of which are hazardous (e.g. neutrons). The photon luminescence or albedo of the lunar surface induced by GCRs and SEPs will be derived here, demonstrating that the Moon literally glows in the dark (when there is no sunlight or Earthshine). This extends earlier work on the same subject [1-4]. A side-by-side comparison of these two albedos and related mitigation measures will also be discussed.

  4. A Luminescent Metal-Organic Framework Thermometer with Intrinsic Dual Emission from Organic Lumophores.

    Science.gov (United States)

    Zhang, Hao; Lin, Chensheng; Sheng, Tianlu; Hu, Shengmin; Zhuo, Chao; Fu, Ruibiao; Wen, Yuehong; Li, Haoran; Su, Shaodong; Wu, Xintao

    2016-03-18

    A new mixed-ligand metal-organic framework (MOF), ZnATZ-BTB, has been constructed as a luminescent ratiometric thermometer by making use of the intrinsic dual emission at cryogenic temperatures. Its twofold interpenetrated network promotes the Dexter energy transfer (DET) between the mixed organic lumophores. The temperature-dependent luminescent behavior arises from the thermal equilibrium between two separated excited states coupled by DET, which is confirmed by Boltzmann distribution fitting. The small excited-state energy gap allows ZnATZ-BTB to measure and visualize cryogenic temperatures (30-130 K) with significantly high relative sensitivity (up to 5.29% K(-1) at 30 K). Moreover, it is the first example of a ratiometric MOF thermometer the dual emitting sources of which are widely applicable mixed organic ligands, opening up new opportunities for designing such devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Recent Advance of Biological Molecular Imaging Based on Lanthanide-Doped Upconversion-Luminescent Nanomaterials

    Directory of Open Access Journals (Sweden)

    Yuanzeng Min

    2014-02-01

    Full Text Available Lanthanide-doped upconversion-luminescent nanoparticles (UCNPs, which can be excited by near-infrared (NIR laser irradiation to emit multiplex light, have been proven to be very useful for in vitro and in vivo molecular imaging studies. In comparison with the conventionally used down-conversion fluorescence imaging strategies, the NIR light excited luminescence of UCNPs displays high photostability, low cytotoxicity, little background auto-fluorescence, which allows for deep tissue penetration, making them attractive as contrast agents for biomedical imaging applications. In this review, we will mainly focus on the latest development of a new type of lanthanide-doped UCNP material and its main applications for in vitro and in vivo molecular imaging and we will also discuss the challenges and future perspectives.

  6. Numerical simulation and phantom experiment of X-ray luminescence computed tomography

    OpenAIRE

    Zhang, Kun

    2015-01-01

    X-ray luminescence computed tomography (XLCT) is an emerging hybrid modality in which X-ray excitable particles (phosphor particles) emit optical photons when stimulated with X-ray photons. Optical imaging has high measurement sensitivity but it has limited spatial resolution for deep targets due to high scattering of optical photons. X-ray imaging has high spatial resolution yet its sensitivity is limited. XLCT can potentially combine the high spatial resolution of x-ray imaging with the hig...

  7. Spectral properties and anti-Stokes luminescence of TeO2-BaF2:Ho3+, Ho3+/Yb3+ ceramics and glass excited by 1.9-μm radiation of a Tm:LiYF4 laser

    Science.gov (United States)

    Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Perunin, I. Yu.; Krasheninnikova, O. V.; Grishin, I. A.

    2017-07-01

    We demonstrate the up-conversion of Tm:LiYF4 infrared (IR) laser radiation with 1908-nm wavelength into visible light with a spectral maximum at 650 nm by ceramics with a composition of (100 - x)TeO2- xBaF2 - 1 wt % HoF3- yYbF3, where x = 20, 30, or 40 mol % and y = 0 or 0.5 wt %. The samples of 60TeO2-40BaF2 - 1 wt % HoF3 - 0.5 wt % YbF3 exhibited anti-Stokes luminescence at a threshold radiation power density of 1.0-1.5 W cm-2.

  8. Long-lasting luminescence in ZnGa2O4: Cr3+ through persistent energy transfer

    Science.gov (United States)

    Li, Lei; Wang, Yinhai; Huang, Haiju; Li, Hong; Zhao, Hui

    2016-01-01

    Cr3+-doped zinc gallate (ZnGa2O4) near-infrared (NIR) phosphors were synthesized via a high temperature solid state method. The luminescence properties of the phosphors were studied systematically. A significant spectra overlap between the emission of ZnGa2O4 and the absorption of Cr3+ was observed and 300 nm excitation exhibited the most excellent long-lasting luminescence properties among the three main excitation bands. Luminescence intensity was changed with the ratio of Ga3+/Cr3+ and the blue host emission of ZnGa2O4 was suppressed when doping Cr3+ into ZnGa2O4. The fluorescence decay curves of blue emission of ZnGa2O4 with different Cr3+ doping concentrations indicated that the lifetime of ZnGa2O4 at 505 nm become shorter with the increase of the Cr3+ concentration. Herein, a possible mechanism of long-lasting luminescence in ZnGa2O4: Cr3+ was proposed that the NIR long-lasting luminescence in ZnGa2O4: Cr3+ comes from the persistent energy transfer from ZnGa2O4 to Cr3+.

  9. LUMINESCENCE DIAGNOSTICS OF TUMORS WITH UPCONVERSION NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    V. V. Rocheva

    2016-01-01

    Full Text Available Background: To improve quality of surgery in oncology, it is necessary to completely remove the tumor, including its metastases, to minimize injury to normal tissues and to reduce duration of an intervention. Modern methods of detection based on radiological computerized tomography and magnetic resonance imaging can identify a tumor after its volume has become big enough, i.e. it contains more than 10 billion cells. Therefore, an improvement of sensitivity and resolution ability of diagnostic tools to identify early stages of malignant neoplasms seems of utmost importance. Aim: To demonstrate the potential of a new class of anti-Stokes luminescence nanoparticles for deep optical imaging with high contrast of malignant tumors. Materials and methods: Upconversion nanoparticles with narrow dispersion and a  size of 70 to 80  nm, with a  core/shell structure of NaYF4:Yb3+:Tm3+/NaYF4 were used in the study. The nanoparticles have an intensive band of anti-Stokes photoluminescence at a wavelength of 800  nm under irradiation with a  wavelength of 975  nm (both wavelengths are within the transparency window for biological tissues. The conversion coefficient of the excitation radiation into the anti-Stokes luminescence was 9%. To increase the time during which nanoparticles can circulate in blood flow of small animals, the nanoparticles were covered by a  biocompatible amphiphilic polymer shell. As a  tumor model we used Lewis epidermoid carcinoma transfected to mice. Results: We were able to obtain stable water colloids of nanoparticles covered with amphiphilic polymer that could preserve their initial size at least for one month. The use of upconversion nanoparticles with a  hydrophilic shell made of intermittent maleic anhydride and octadecene co-polymer with subsequent coating with diglycidyl polyethylene glycol ether allowed for reduction of non-specific reaction of nanoparticles with plasma proteins. In its turn, it resulted in an

  10. Assessment of terbium (III) as a luminescent probe for the detection of tuberculosis biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Bamogo, W. [CNRS, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France); Mugherli, L. [CEA, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France); Banyasz, A. [CNRS, IRAMIS, LIDyL/Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette (France); Novelli-Rousseau, A.; Mallard, F. [BioMérieux SA, F-38000 Grenoble (France); Tran-Thi, T.-H., E-mail: thu-hoa.tran-thi@cea.fr [CNRS, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France)

    2015-10-08

    A detection method for nicotinic acid, a specific metabolite marker of Mycobacterium tuberculosis present in cultures and patients' breath, is studied in complex solutions containing other metabolites and in biological media such as urine, saliva and breath condensate. The method is based on the analysis of the luminescence increase of Tb{sup 3+} complexes in the presence of nicotinic acid due to the energy transfer from the excited ligand to the lanthanide ion. It is shown that other potential markers found in M. tuberculosis culture supernatant, such as methyl phenylacetate, p-methyl anisate, methyl nicotinate and 2-methoxy biphenyl, can interfere with nicotinic acid via a competitive absorption of the excitation photons. A new strategy to circumvent these interferences is proposed with an upstream trapping of volatile markers preceding the detection of nicotinic acid in the liquid phase via the luminescence of Tb{sup 3+} complexes. The cost of the method is evaluated and compared with the Xpert MTB/RIF test endorsed by the World Health Organization. - Highlights: • Nicotinic acid, a specific marker of M. tuberculosis, can be detected via luminescence. • The detection limit with a commercial phosphorimeter is 0.4 µmol·L{sup -1}. • Other metabolites of M. tuberculosis can interfere via absorbed excitation light. • The interference can be removed via trapping of the most volatile metabolites. • A breath analysis procedure's cost is compared with the Xpert TBM/RIF test.

  11. Luminescence induced by electrons outside zinc oxide nanoparticles driven by intense terahertz pulse trains

    Science.gov (United States)

    Nagai, Masaya; Aono, Shingo; Ashida, Masaaki; Kawase, Keigo; Irizawa, Akinori; Isoyama, Goro

    2017-05-01

    We investigated the behaviours of electrons from ZnO nanoparticles via a strong terahertz field. Luminescence from ZnO nanoparticles and surrounding nitrogen molecules was observed when the nanoparticles were irradiated with a terahertz free-electron laser (FEL). These excitations arose from the collision of electrons released via field electron emission with the ZnO nanoparticles and neighbouring nitrogen molecules. The strong excitation frequency dependence of the luminescence reflected the kinetic energy and trajectory of electrons outside the nanoparticles. We also observed spectral changes in the luminescence during macropulses of the FEL, even though the carrier lifetime of the nanoparticles was shorter than the interval between the micropulses. These changes were caused by the nanoparticles becoming charged due to electron emission, resulting in the electrons being re-emitted outside the nanoparticles. The electrons outside the nanoparticles were accelerated more efficiently by the terahertz field than the electrons inside the nanoparticles, and thus the motion of these exterior electrons provided a new excitation path.

  12. Eu2+-activated Ba3Ca3(PO4)4 phosphor with doping-concentration dependent luminescence

    Science.gov (United States)

    Tang, Huidong; Yang, Rong; Li, Rongzhu

    2017-10-01

    A color tunable phosphor of Eu2+-activated monophosphate Ba3Ca3(PO4)4 was developed via facile solid-state reaction synthesis. The samples were tested by X-ray powder diffraction (XRD) patterns, morphological properties, luminescence and decay lifetime measurements. The structural characteristics were discussed. The excitation bands of the phosphors cover the UV-, near-UV and blue-wavelength bands extending from 300 to 440 nm. The luminescence spectra of the phosphors show a great dependence on the Eu2+-concentration in Ba3Ca3(PO4)4, which can give blue to yellow emission colors. There are two kinds of Eu2+ centers in Ba3Ca3(PO4)4 lattices, which give yellow (EuI) and blue (EuII) luminescence with the maximum wavelength at 565 nm and 450 nm, respectively. The structural occupations and luminescence properties of EuI and EuII centers were discussed. EuI (yellow center) has a dominant contribution to the total luminescence with the increase of the Eu2+-doping level. The luminescence internal quantum efficiency and thermal stability (activation energy) were reported. The reported results could be helpful for the further potential application of the phosphor.

  13. Violet stimulated luminescence: geo- or thermochronometer?

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Guralnik, Benny; Porat, N.

    2015-01-01

    The method of quartz optically stimulated luminescence (OSL) dating is widely used, but generally limited to the past ~0.1 million years (Ma) due to early saturation of the desired signal. Violet stimulated luminescence (VSL) of quartz has previously been shown as a promising alternative, with a ...

  14. Receptor-Targeted Luminescent Silver Bionanoparticles

    NARCIS (Netherlands)

    Bunschoten, Anton; Chin, Patrick T.K.; Buckle, Tessa; Linden, van der Marte; Barendregt, Arjan; Verheijen, Marcel A.; Leeuwen, van Fijs W.B.

    2016-01-01

    Luminescent Ag nanoclusters (Ag-NC) provide the next generation in bionanoparticles, wherein the luminescence (650 nm) and large Stokes shift of these inorganic nanoclusters are favorable for biological imaging. By combining these characteristics with those of human serum albumin (HSA; a protein

  15. Luminescence of thermally altered human skeletal remains

    NARCIS (Netherlands)

    Krap, Tristan; Nota, Kevin; Wilk, Leah; van de Goot, Frank; Ruijter, Jan; Duijst, Wilma; Oostra, Roelof Jan

    2017-01-01

    Literature on luminescent properties of thermally altered human remains is scarce and contradictory. Therefore, the luminescence of heated bone was systemically reinvestigated. A heating experiment was conducted on fresh human bone, in two different media, and cremated human remains were recovered

  16. Kinetics of infrared stimulated luminescence from feldspars

    DEFF Research Database (Denmark)

    Jain, Mayank; Sohbati, Reza; Guralnik, Benny

    2015-01-01

    thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same...

  17. Synthesis and enhancement of luminescence intensity by co-doping of M+ (M = Li, Na, K) in Ce3+ doped strontium haloborate

    Science.gov (United States)

    Gawande, A. B.; Sonekar, R. P.; Omanwar, S. K.

    2014-05-01

    Photoluminescence properties of Ce3+ doped strontium haloborates synthesized by solution combustion technique were studied. Sr2B5O9Cl:Ce3+ produce emission band peaking at 345 nm under 307 nm excitation radiation. Enhancement of luminescence intensity was observed when M+ (Li+, Na+, K+) ions were used as co-dopant in Sr2B5O9Cl:Ce3+. Charge compensation by Na+ ion in Sr2B5O9Cl:Ce3+ show strongest luminescence intensity at 345 nm under 307 nm excitation radiation.

  18. Thermal quenching of luminescence processes in feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Duller, G.A.T.

    1995-01-01

    of these processes is, in general, thermally dependent, and leads either to enhancement or quenching of the luminescence with increasing temperature. Previous studies have measured the combined thermal activation characteristics of all three processes, and show a strong dependence on stimulation energy......The technique of optically stimulated luminescence has important uses in the dose evaluation of irradiated feldspars. The luminescence process involves the eviction of electrons from donor traps, charge transfer through the conduction band, and recombination at acceptor sites; each....... In this article, an initial attempt is made to isolate only the recombination part of the luminescence cycle, and determine its thermal characteristics separately. A Variety of luminescence transitions are examined in a range of both alkali and plagioclase feldspars; three distinct emission types are identified...

  19. Metal plasmon enhanced europium complex luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Liu Feng [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Aldea, Gabriela [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada); Petru Poni Institute of Macromolecular Chemistry Iasi, Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Nunzi, Jean-Michel, E-mail: nunzijm@queensu.c [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada)

    2010-01-15

    The plasmon enhanced luminescence of a rare-earth complex Tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (Eu(fod){sub 3}) was investigated. A polyvinyl alcohol (PVA) thin film was successfully adopted as a spacer to separate the Eu complex from the silver island film (SIF), and five-fold enhancement of the radiative decay rate of the Eu complex on SIF was demonstrated based on the luminescence intensity and lifetime measurement. Investigation of the distance dependent luminescence indicates that 7 nm is an optimal distance for SIF enhanced Eu luminescence. Plasmon enhanced rare-earth luminescence based on an organic film spacer would find potential applications in plasmon enhanced organic light emitting diode (OLED) devices.

  20. Persistent luminescence induced by near infra-red photostimulation in chromium-doped zinc gallate for in vivo optical imaging

    Science.gov (United States)

    Sharma, Suchinder K.; Gourier, Didier; Teston, Eliott; Scherman, Daniel; Richard, Cyrille; Viana, Bruno

    2017-01-01

    The analysis of the optical spectroscopy of the Cr3+ doped spinel was initiated by Prof. Georges Boulon more than twenty years ago. More recently persistent luminescence nanoparticles of Cr doped zinc gallate have found interest for in vivo imaging of small animals. Here we evaluated near infra-red (NIR) excitation (or NIR photostimulation) via photo-transfer mechanism as an additional tool for in vivo optical imaging. Investigation of the persistent luminescence induced by NIR photostimulation is studied after either a primary UV (band-to-band excitation) or visible irradiation (direct Cr 3d-3d excitation). UV or visible pre-excited ZnGa2O4:Cr (ZGO:Cr) nanoparticles are kept active during several days thanks to deep traps (with depths 1 eV-1.2 eV) observed in these samples which can be probed through thermally stimulated luminescence (TSL) technique showing glow curve maximums at 470 K and 530 K upon visible light excitation. These deep traps are stable at room temperature but can be emptied by NIR light photostimulation. Experiments were carried out to study the photostimulation induced trapping-detrapping in the ZGO:Cr phosphor. Photostimulation was also tested in vivo for small animal optical imaging to offer new perspectives and modalities.

  1. The temperature behavior and mechanism of exciton luminescence in quantum dots.

    Science.gov (United States)

    Zatsepin, A F; Biryukov, D Yu

    2017-07-19

    The processes of direct and indirect optical excitation of spatially confined excitons in quantum dots (QDs) embedded in a silica thin-film matrix have been reported and discussed. A generalized scheme for the electronic transitions is employed for a detailed description of luminescence temperature behavior using various excitation methods. This scheme considers three different models of exciton relaxation and substantiates the occupation of the triplet radiative states as a result of singlet-triplet intersystem crossing or excitation energy transfer from free excitons of the matrix. Analytical expressions describing five types of different temperature curves were derived. It is established that their shapes are exactly defined by the excitation mechanism and the parameters involved in the numerical model. The conditions allowing the estimation of the energy and kinetic characteristics of QD photoluminescence are formulated. We have shown that the confinement effect causes a decrease in the thermal activation barriers and frequency characteristics for non-radiative transitions. An application of the developed concepts allows predicting and estimating the temperature dependences for direct and indirect optically excited QD luminescence employing silicon nanoclusters in a silica thin-film matrix as an example.

  2. Second harmonic generation and two-photon luminescence upconversion in glasses doped with ZnSe nanocrystalline quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Thantu, Napoleon [Idaho National Engineering and Environmental Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)]. E-mail: Napoleon.Thantu@ngc.com

    2005-01-01

    We report two-photon excited emission in borosilicate glasses doped with ZnSe nanocrystalline quantum dots. The emission, predominantly near the two-photon energy and detected in the direction of the excitation beam, is in the visible, and the fundamental excitation is the near-infrared output of a tunable femtosecond laser. Depending on the two-photon energy, time- and frequency-resolved measurements at room temperature reveal that the emission largely consists of second harmonic generation (SHG) and two-photon luminescence upconversion, and a much smaller luminescence from redshifted, low-lying trap states and other trap levels residing near the semiconductor band edge. We discuss the SHG origin in terms of bulk-like and surface contributions from the nanocrystals and the two-photon resonant enhancement near the excitonic absorption.

  3. Luminescence study of lanthanide(III) ions in non-aqueous solutions containing azide ions

    Energy Technology Data Exchange (ETDEWEB)

    Lis, S.; Kimura, T.; Yoshida, Z.; But, S

    2004-10-20

    Luminescence lifetime and intensity measurements of lanthanide(III) ions, Ln{sup 3+} (Eu, Gd and Tb), in non-aqueous solutions containing azide ions (N{sub 3}{sup -}) have been performed to study the quenching effect of N{sub 3}{sup -} using time-resolved laser-induced luminescence spectroscopy and conventional luminescence spectroscopy. The luminescence Stern-Volmer quenching constants K{sub sv}{sup P}HI and azide non-radiative decay constants k{sub N{sub 3}} of the excited Eu(III) ion in the presence of N{sub 3}{sup -} were measured in N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylformamide (NMF), formamide (FA) and methanol (MeOH). The obtained quenching effect of the Ln{sup 3+} luminescence by azide in the non-aqueous solvents shows the order: Gd>Eu>Tb, which does not obey the energy gap law, {delta}E, between the emitting and the ground state of the Ln{sup 3+} ion (Gd>Tb>Eu). The anomaly in the quenching pattern observed in the case of Eu{sup 3+} can be attributed to its partial reduction to Eu{sup 2+}, additionally to the energy transfer from excited state of Eu{sup 3+} to N{sub 3}{sup -}. The values of quenching rate constants k{sub N{sub 3}} measured for Eu{sup 3+} in various solutions depend on the acceptor number (AN) of the solvents used.

  4. Electron paramagnetic resonance and luminescence of chromium in calcium germanate crystals

    CERN Document Server

    Gorshkov, O N; Tyurin, S A; Chigineva, A B; Chigirinskij, Y I

    2002-01-01

    One observed luminescence of Cr sup 4 sup + :Ca sub 2 GeO sub 4 single crystals near 1.3 mu m wave length at excitation by a semiconducting laser up to 573 K. At T < 110 K one detected the EPR spectrum identified as one belonging to Cr sup 4 sup + ions substituting for germanium. One determined the components of g-tensor and its basic axes. In calcium germanate this impurity centre slightly violates crystal symmetry. Detected deviation from the Curie law in EPR temperature dependence is explained by transition into the excited state with activation low energy. The giant efficient multiplicity of degeneration of the excited state is explained by induction of soft phonon modes of crystal at excitation of a defect

  5. Electrons in feldspar II: A consideration of the influence of conduction band-tail states on luminescence processes

    DEFF Research Database (Denmark)

    Poolton, H.R.J.; Ozanyan, K.B.; Wallinga, J.

    2002-01-01

    consider what influence the band tails have on the luminescence properties of feldspar, where electrons travel through the sample prior to recombination. The work highlights the dominant role that 0.04-0.05-eV phonons play in both the luminescence excitation and emission processes of these materials...... electrons can travel, but with reduced mobility: transport through these states is expected to be thermally activated. The purpose of this article is twofold. Firstly, we consider what kind of lattice perturbations could give rise to both localized and extended conduction band-tail states. Secondly. we...

  6. Lanthanide-doped luminescent ionogels.

    Science.gov (United States)

    Lunstroot, Kyra; Driesen, Kris; Nockemann, Peter; Van Hecke, Kristof; Van Meervelt, Luc; Görller-Walrand, Christiane; Binnemans, Koen; Bellayer, Séverine; Viau, Lydie; Le Bideau, Jean; Vioux, André

    2009-01-14

    Ionogels are solid oxide host networks confining at a meso-scale ionic liquids, and retaining their liquid nature. Ionogels were obtained by dissolving lanthanide(III) complexes in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][Tf2N], followed by confinement of the lanthanide-doped ionic liquid mixtures in the pores of a nano-porous silica network. [C6mim][Ln(tta)4], where tta is 2-thenoyltrifluoroacetonate and Ln=Nd, Sm, Eu, Ho, Er, Yb, and [choline]3[Tb(dpa)3], where dpa=pyridine-2,6-dicarboxylate (dipicolinate), were chosen as the lanthanide complexes. The ionogels are luminescent, ion-conductive inorganic-organic hybrid materials. Depending on the lanthanide(III) ion, emission in the visible or the near-infrared regions of the electromagnetic spectrum was observed. The work presented herein highlights that the confinement did not disturb the first coordination sphere of the lanthanide ions and also showed the excellent luminescence performance of the lanthanide tetrakis beta-diketonate complexes. The crystal structures of the complexes [C6mim][Yb(tta)4] and [choline]3[Tb(dpa)3] are reported.

  7. UV luminescence of dendrimer-encapsulated gold nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Hyeong Seop; Kim, Jun Myung; Sohn, So Hyeong; Han, Noh Soo; Park, Seung Min [Dept. of Chemistry, Kyung Hee University, Seoul (Korea, Republic of)

    2016-10-15

    Size-dependent luminescence color is one of the interesting properties of metal nanocrystals, whose sizes are in the dimension of the Fermi wavelength of an electron. Despite the short Fermi wavelength of electrons in gold (-0.7 nm), luminescence of gold nanoclusters has been reported to range from the near-infrared to near-ultraviolet, depending on the number of atoms in the nanoclusters. The photoluminescence of G4-OH (Au) obtained by the excitation of 266 nm showed UV emission in addition to the well-known blue emission. The higher intensity and red-shifted emission of the gold nanoclusters was distinguished from the emission of dendrimers. The UV emission at 352 nm matched the emission energy of Au{sub 4} in the spherical jellium model, rather than the planar Au{sub 8}, which supported the emission of Au{sub 4} formed in G4-OH. Despite the change of [HAuCl{sub 4} ]/[G4-OH], the relative population between Au{sub 4} and Au{sub 8} was similar in G4-OH(Au), which indicated that the closed electronic and geometric structures stabilized the magic number of Au{sub 4}.

  8. Review of biomedical Čerenkov luminescence imaging applications.

    Science.gov (United States)

    Tanha, Kaveh; Pashazadeh, Ali Mahmoud; Pogue, Brian W

    2015-08-01

    Čerenkov radiation is a fascinating optical signal, which has been exploited for unique diagnostic biological sensing and imaging, with significantly expanded use just in the last half decade. Čerenkov Luminescence Imaging (CLI) has desirable capabilities for niche applications, using specially designed measurement systems that report on radiation distributions, radiotracer and nanoparticle concentrations, and are directly applied to procedures such as medicine assessment, endoscopy, surgery, quality assurance and dosimetry. When compared to the other imaging tools such as PET and SPECT, CLI can have the key advantage of lower cost, higher throughput and lower imaging time. CLI can also provide imaging and dosimetry information from both radioisotopes and linear accelerator irradiation. The relatively short range of optical photon transport in tissue means that direct Čerenkov luminescence imaging is restricted to small animals or near surface human use. Use of Čerenkov-excitation for additional molecular probes, is now emerging as a key tool for biosensing or radiosensitization. This review evaluates these new improvements in CLI for both medical value and biological insight.

  9. Characterization of a nondestructive beam profile monitor using luminescent emission

    Directory of Open Access Journals (Sweden)

    A. Variola

    2007-12-01

    Full Text Available The LHC (large hadron collider [LHC study group: LHC. The large hadron collider conceptual design; CERN/AC/95-05] is the future p-p collider under construction at CERN, Geneva. Over a circumference of 26.7 km a set of cryogenic dipoles and rf cavities will store and accelerate proton and ion beams up to energies of the order of 7 TeV. Injection in LHC will be performed by the CERN complex of accelerators, starting from the source and passing through the linac, the four booster rings, the proton synchrotron (PS, and super proton synchrotron (SPS accelerators. One of the main constraints on LHC performance is emittance preservation along the whole chain of CERN accelerators. The accepted relative normalized emittance blowup after filamentation is ±7%. To monitor the beam and the emittance blowup process, a study of different prototypes of nonintercepting beam profile monitors has been performed. In this context a monitor using the luminescent emission of gases excited by ultrarelativistic protons (450 GeV was developed and tested in the SPS ring. The results of beam size measurements and their evolution as a function of the machine parameters are presented. The image quality and resolution attainable in the LHC case have been assessed. A first full characterization of the luminescence cross section, spectrum, decay time, and afterglow effect for an ultrarelativistic proton beam is provided. Some significant results are also provided for lead ion beams.

  10. Isovector monopole excitation energies

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, J.D.; Lipparini, E.; Stringary, S.

    1987-11-05

    Using a hydrodynamical model whose parameters have been adjusted to fit the polarizability and excitation energy of the giant dipole nuclear resonance we predict excitation energies of the isovector monopole resonance. The predicted values are in good agreement with experimental data. The mass dependence of the excitation energy is strongly influenced by nuclear geometry.

  11. The application of visible-induced luminescence imaging to the examination of museum objects

    Science.gov (United States)

    Verri, G.

    2009-07-01

    Visible-induced luminescence imaging in the near infrared range (800-1700 nm) can play a key role in the spatial characterization of certain historical blue pigments (principally Egyptian blue, Han blue and Han purple). All three of these pigments show a very strong infrared emission when excited across the visible range. The setup required for this type of measurement comprises a recording device with some sensitivity to near infrared radiation and an excitation source in the visible range. Inexpensive and widely available excitation radiation sources that can be used for this application include fluorescent lamps and LEDs. While visible LEDs do not usually emit infrared radiation, commercially available fluorescent tubes may emit some stray infrared radiation. Although the presence of such stray infrared radiation may in some cases be considered beneficial, allowing the user easily to locate the presence of the pigments under investigation within the composition of the piece, it can be easily removed using a simple subtraction method. This method, based on the measurement of the reflective properties of the surface under investigation in the emission range of the luminescent pigments, is described. The emission results obtained for Egyptian blue, Han blue and Han purple are compared to those of a set of representative historical and modern blue pigments, including manganese blue, which was the only other pigment found to show detectable luminescence properties. Examples of the application of visible-induced luminescence imaging to archaeological objects of the Antonine period (AD 100-200) in the collections of the British Museum are also presented.

  12. TOPICAL REVIEW: Discrete breathers and the anomalous decay of luminescence

    Science.gov (United States)

    Mihóková, E.; Schulman, L. S.

    2010-05-01

    Some years ago an anomaly was noted in the decay of luminescence in certain doped alkali halides. The anomaly was eventually explained using a factor 1 billion (109) slowdown in lattice relaxation, a remarkable stretching of time scales. This slowdown was found to be caused by the creation of a 'breather' in the neighborhood of the dopant. Discrete breathers are nondispersive classical excitations that are known to be significant in many natural systems. Broad ranging reviews of mathematical techniques and physical applications have recently appeared. In the present review we focus on the occurrence of breathers in doped alkali halides. Several more general properties of breathers have arisen from this study and these are presented as well. Among them is the study of the quantum breather, its quantization and stability, a topic less fully explored than the classical theory because it does not yield easily to numerical simulation.

  13. Luminescent properties of Mn{sup 2+} doped apatite nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Ravindranadh, K.; Rao, M. C., E-mail: raomc72@gmail.com [Department of Physics, Andhra Loyola College, Vijayawada-520 008 (India); Ravikumar, R. V. S. S. N. [Department of Physics, Acharya Nagarjuna University, Guntur-522 510 (India)

    2016-05-06

    Nanophosphors have been extensively investigated during the last decade due to their various high-performance application potential such as lamp industry, radiation dosimetry, X-ray imaging and colour display. The synthesis of inorganic nanophosphors using both ionizing radiation (IR) or UV light represents very promising technological field. Alkaline earth nanophosphors gathered a lot of attention in past decades because they are considered to be excellent host materials. Transition-metal oxides are well known luminescent emitters in the visible spectral region. Mn{sup 2+} doped calcium-lithium hydroxyapatite (CLHA) nanophosphors were prepared by mechanochemical synthesis. The prepared samples were characterized by photoluminescence studies. Photoluminescence spectra of Mn{sup 2+} doped CLHA nanophosphors exhibited green and strong orange emission bands at 534, 577 nm respectively under the excitation wavelength of 365 nm. The CIE chromaticity coordinates were also calculated from emission spectra for Mn{sup 2+} doped CLHA nanophosphors.

  14. Luminescent properties of Mn2+ doped apatite nanophosphors

    Science.gov (United States)

    Ravindranadh, K.; Ravikumar, R. V. S. S. N.; Rao, M. C.

    2016-05-01

    Nanophosphors have been extensively investigated during the last decade due to their various high-performance application potential such as lamp industry, radiation dosimetry, X-ray imaging and colour display. The synthesis of inorganic nanophosphors using both ionizing radiation (IR) or UV light represents very promising technological field. Alkaline earth nanophosphors gathered a lot of attention in past decades because they are considered to be excellent host materials. Transition-metal oxides are well known luminescent emitters in the visible spectral region. Mn2+ doped calcium-lithium hydroxyapatite (CLHA) nanophosphors were prepared by mechanochemical synthesis. The prepared samples were characterized by photoluminescence studies. Photoluminescence spectra of Mn2+ doped CLHA nanophosphors exhibited green and strong orange emission bands at 534, 577 nm respectively under the excitation wavelength of 365 nm. The CIE chromaticity coordinates were also calculated from emission spectra for Mn2+ doped CLHA nanophosphors.

  15. Luminescent Probes for Sensitive Detection of pH Changes in Live Cells through Two Near-Infrared Luminescence Channels.

    Science.gov (United States)

    Zhang, Shuwei; Chen, Tzu-Ho; Lee, Hsien-Ming; Bi, Jianheng; Ghosh, Avik; Fang, Mingxi; Qian, Zichen; Xie, Fei; Ainsley, Jon; Christov, Christo; Luo, Fen-Tair; Zhao, Feng; Liu, Haiying

    2017-07-28

    Two water-soluble near-infrared luminescent probes, which possess both conventional intense Stokes fluorescence and unique single-photon frequency upconversion luminescence (FUCL), were developed for sensitive and selective detection of pH changes in live cells. The water solubility and biocompatibility of these probes were achieved by introducing mannose residues through 2,2'-(ethylenedioxy)diethylamine tethered spacers to a near-infrared conventional fluorescence (CF) and FUCL organic fluorophore. At a pH higher than 7.4, the probes have ring-closed spirocyclic lactam structures, thus are colorless and nonfluorescent. Nevertheless, they sensitively respond to acidic pH values, with a drastic structural change to ring-opened spirocyclic lactam forms, which cause significant absorbance increases at 714 nm. Correspondingly, their near-infrared CF and FUCL intensities at 740 nm are also significantly enhanced when excited by 690 and 808 nm, respectively. The probes hold a variety of advantages such as high sensitivity, excellent reversibility and selectivity to pH over metal ions, low cellular autofluorescence background interference, good cell membrane permeability and photostability, as well as low cytotoxicity. Our results have successfully proven that these probes can visualize intracellular lysosomal pH changes in live cells by monitoring both near-infrared CF and FUCL changes.

  16. Polymeric Luminescent Compositions Doped with Beta-Diketonates Boron Difluoride as Material for Luminescent Solar Concentrator

    Science.gov (United States)

    Khrebtov, A. A.; Fedorenko, E. V.; Reutov, V. A.

    2017-11-01

    In this paper we investigated polymeric luminescent compositions based on polystyrene doped with beta diketonates boron difluoride. Transparent films with effective absorption in the ultraviolet and blue regions of the spectrum were obtained. Polymeric luminescent compositions based on the mixture of dyes allow expanding the absorption region and increase the radiation shift. A luminescent solar concentrator consisting of a glass plate coated with such film can be used for photovoltaic window application.

  17. LUMINESCENT KINETIC CHARACTERISTICS OF CsPbCl3 AGGREGATES DISPERSED IN Rb1-xCsxCl (x=0.05-0.2 MATRICES

    Directory of Open Access Journals (Sweden)

    S.Myagkota

    2003-01-01

    Full Text Available The luminescent kinetic parameters of the CsPbCl3 nanocrystals dispersed in matrices of solid solutions Rb1-xCsxCl (x=0.05-0.2 were studied under pulse synchrotron radiation excitation. Formation of CsPbCl3 nanocrystals is confirmed by manifestation of the quantum size effect, which is displayed by a short-wave shift of the exciton luminescence maximum and an essential shortening of the luminescence decay time for of CsPbCl3 nanocrystals as compared to that for an excitonic luminescence of a bulk single crystal CsPbCl3. For the first time, using the atomic force microscopy method, the lead-containing nanocrystals embedded in a matrix of the Rb0.95Cs0.05Cl solid solution have been directly observed.

  18. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  19. Persistent Luminescence Hole-Type Materials by Design: Transition-Metal-Doped Carbon Allotrope and Carbides.

    Science.gov (United States)

    Qu, Bingyan; Zhang, Bo; Wang, Lei; Zhou, Rulong; Zeng, Xiao Cheng; Li, Liang

    2016-03-02

    Electron traps play a crucial role in a wide variety of compounds of persistent luminescence (PL) materials. However, little attention has been placed on the hole-trap-type PL materials. In this study, a novel hole-dominated persistent luminescence (PL) mechanism is predicted. The mechanism is validated in the night pearl diamond (NPD) composed of lonsdaleite with ultralong persistent luminescence (PL) (more than 72 h). The computed band structures suggest that the Fe ion dopant in lonsdaleite is responsible for the luminescence of NPD due to the desired defect levels within the band gap for electronic transition. Other possible impurity defects in lonsdaleite, such as K, Ca, Mg, Zn, or Tl dopants, or C vacancy can also serve as the hole-trap centers to enhance the PL. Among other 3d transition-metal-ion dopants considered, Cr and Mn ions are predicted to give rise to PL property. The predicted PL mechanism via transition-metal doping of lonsdaleite offers an exciting opportunity for engineering new PL materials by design.

  20. Luminescent solutions and films of new europium complexes with chelating ligands

    Science.gov (United States)

    Kharcheva, Anastasia V.; Ivanov, Alexey V.; Borisova, Nataliya E.; Kaminskaya, Tatiana P.; Patsaeva, Svetlana V.; Popov, Vladimir V.; Yuzhakov, Viktor I.

    2015-03-01

    The development of new complexes of rare earth elements (REE) with chelating organic ligands opens up the possibility of purposeful alteration in the composition and structure of the complexes, and therefore tuning their optical properties. New ligands possessing two pyridine rings in their structure were synthesized to improve coordination properties and photophysical characteristics of REE compounds. Complexes of trivalent europium with novel chelating ligands were investigated using luminescence and absorption spectroscopy, as well as atomic force microscopy. Luminescence properties of new compounds were studied both for solutions and films deposited on the solid support. All complexes exhibit the characteristic red luminescence of Eu (III) ion with the absolute lumenescence quantum yield in polar acetonitrile solution varying from 0.21 to 1.45 % and emission lifetime ranged from 0.1 to 1 ms. Excitation spectra of Eu coordination complexes correspond with absorption bands of chelating ligand. The energy levels of the triplet state of the new ligands were determined from the phosphorescence at 77 K of the corresponding Gd (III) complexes. The morphology of films of europium complexes with different substituents in the organic ligands was investigated by atomic force microscopy (AFM). It strongly depends both on the type of substituent in the organic ligand, and the rotation speed of the spin-coater. New europium complexes with chelating ligands containing additional pyridine fragments represent outstanding candidates for phosphors with improved luminescence properties.

  1. Synthesis of porous silicon nano-wires and the emission of red luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Congli, Sun [School of Materials Science and Engineering, Sichuan University (China); Hao, Hu [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, Sichuan (China); Huanhuan, Feng; Jingjing, Xu; Yu, Chen; Yong, Jin; Zhifeng, Jiao [School of Materials Science and Engineering, Sichuan University (China); Xiaosong, Sun, E-mail: sunxs@scu.edu.cn [School of Materials Science and Engineering, Sichuan University (China)

    2013-10-01

    This very paper is focusing on the characterization of porous silicon nano-wires prepared via a two-step route, the electroless chemical etching and the following post-treatment of HF/HNO{sub 3} solution. Hence, scanning electron microscopy, transmission electron microscopy and confocal fluorescence microscopy are employed for this purpose. From the results of experiments, one can find that the as-prepared silicon nano-wire is of smooth surface and that no visible photo-luminescence emission could be seen. However, the porous structure can be found in the silicon nano-wire treated with HF/HNO{sub 3} solution, and the clear photo-luminescence emission of 630 nm can be recorded with a confocal fluorescence microscope. The transmission electron microscopy test tells that the porous silicon nano-wire is made up of a porous crystalline silicon nano-core and a rough coating of silicon oxide. Besides, based on the post-HF- and -H{sub 2}O{sub 2}- treatments, the emission mechanism of the red luminescence has been discussed and could be attributed to the quantum confinement/luminescence center model which could be simply concluded as that the electron–hole pairs are mainly excited inside the porous silicon nano-core and then tunneling out and recombining at the silicon oxide coating.

  2. Manifestation of unequal arm lengths of uranyl ions in luminescent and oscillating spectra of uranylsufates and molybdates

    Energy Technology Data Exchange (ETDEWEB)

    Serezhkin, V.N.; Serezhkina, L.B.; Fakeyeva, O.A.; Olikov, I.I.

    1981-12-01

    This study was undertaken to determine how the nonuniformity of uranyl ions established by x-ray studies of uranyl molybdate and sulfate is manifested in the luminescent and oscillating spectra of these compounds. IR absorption spectra were recorded from specimens prepared as tablets with KBr or suspensions in vaseline oil. Raman spectra were recorded using a helium-neon laser spectrometer. Luminescent spectra were recorded at 77 K using a mercury-quartz lamp as the excitation source. The data indicate the possibility of detecting nonuniform arm lengths in uranyl ions by analysis of the luminescent and oscillating spectra. However a final answer to this question requires comparison of the spectroscopic and structural characteristics of a broader range of compounds with asymmetrical uranium-oxygen bonds in the uranyl ions.

  3. A novel contrast agent with rare earth-doped up-conversion luminescence and Gd-DTPA magnetic resonance properties

    Science.gov (United States)

    Lu, Qing; Wei, Daixu; Cheng, Jiejun; Xu, Jianrong; Zhu, Jun

    2012-08-01

    The magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF4:Yb, Er were successfully synthesized by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF4:Yb, Er nanoparticles through EDC/NHS coupling chemistry. The as-prepared products were characterized by powder X-ray diffraction, transmission electron microscopy, dynamic light scattering, energy dispersive X-ray analysis, and fourier transform infrared spectrometry. The room-temperature upconversion luminescent spectra and T1-weighted maps of the obtained nanoparticles were carried out by 980 nm NIR light excitation and a 3T MR imaging scanner, respectively. The results indicated that the as-synthesized multifunctional nanoparticles with small size, highly solubility in water, and both high MR relaxivities and upconversion luminescence may have potential usage for MR imaging in future.

  4. Growth and spectral-luminescent study of SrMoO4 crystals doped with Tm3+ ions

    Science.gov (United States)

    Dunaeva, E. E.; Zverev, P. G.; Doroshenko, M. E.; Nekhoroshikh, A. V.; Ivleva, L. I.; Osiko, V. V.

    2016-03-01

    SrMoO4 crystals doped with Tm3+ ions have been produced from a melt using the Czochralski method; their spectral-luminescent characteristics have been studied, and laser radiation has been generated at the wavelength of 1.94 μm using laser-diode excitation. The high absorption section at the wavelength of 795 nm, the fairly high luminescence section, the long lifetime at the upper laser level 3F4 of 1.5 ms, and a wide luminescence band allow one to hope for developing efficient tunable Tm3+: SrMoO4 crystal lasers with diode pumping in the range of 1.7-2.0 μm, which are capable of implementing SRS self-transformation of radiation into the middle IR band.

  5. Efficient manganese luminescence induced by Ce3+-Mn2+ energy transfer in rare earth fluoride and phosphate nanocrystals

    Directory of Open Access Journals (Sweden)

    Ding Yun

    2011-01-01

    Full Text Available Abstract Manganese materials with attractive optical properties have been proposed for applications in such areas as photonics, light-emitting diodes, and bioimaging. In this paper, we have demonstrated multicolor Mn2+ luminescence in the visible region by controlling Ce3+-Mn2+ energy transfer in rare earth nanocrystals [NCs]. CeF3 and CePO4 NCs doped with Mn2+ have been prepared and can be well dispersed in aqueous solutions. Under ultraviolet light excitation, both the CeF3:Mn and CePO4:Mn NCs exhibit Mn2+ luminescence, yet their output colors are green and orange, respectively. By optimizing Mn2+ doping concentrations, Mn2+ luminescence quantum efficiency and Ce3+-Mn2+ energy transfer efficiency can respectively reach 14% and 60% in the CeF3:Mn NCs.

  6. Magnetic tuning of upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite

    Science.gov (United States)

    Dai, Gangtao; Zhong, Zhiqiang; Wu, Xiaofeng; Zhan, Shiping; Hu, Shigang; Hu, Pan; Hu, Junshan; Wu, Shaobing; Han, Junbo; Liu, Yunxin

    2017-04-01

    Lanthanide-doped upconversion nanoparticles (UCNPs) NaGdF4:Yb3+/Er3+ have received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb3+/Er3+ nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while plasmon-enhanced upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite is independent of a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy-level gaps induced by magnetic field and enhance the radiative efficiency, which is the main factor for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T. These findings provide a novel route for exploring the magnetic control of upconversion luminescence in lanthanide-doped bifunctional nanoparticles.

  7. Microwave hydrothermal synthesis and infrared to visible upconversion luminescence of Er{sup 3+}/Yb{sup 3+} co-doped bismuth molybdate nanopowder

    Energy Technology Data Exchange (ETDEWEB)

    Adhikari, Rajesh; Joshi, Bhupendra [Research Center for Eco-Multifunctional Nanomaterials, Sun Moon University (Korea, Republic of); Narro-García, R.; De la Rosa, E. [Centro de Investigaciones en Óptica, A.P. 1-948, León, Gto. 37150 (Mexico); Lee, Soo Wohn, E-mail: swlee@sunmoon.ac.kr [Department of Environmental Engineering, Sun Moon University (Korea, Republic of)

    2014-01-15

    This paper reports the microwave hydrothermal synthesis and infrared to visible upconversion luminescence of Er{sup 3+/}Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} nanopowder. Crystal structure, morphology and chemical composition were analyzed by means of X-ray Diffraction, Transmission Electron Microscopy and Raman Spectroscopy. Upconversion luminescence properties were studied in detail. The infrared to visible upconversion luminescence has been investigated in Er{sup 3+}/Yb{sup 3+} doped Bi{sub 2}MoO{sub 6} with different Yb{sup 3+} concentrations. Intense green and red upconversion emissions around 532, 545, and 655 nm corresponding to the {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, and {sup 4}F{sub 9/2} transitions, respectively, to the {sup 4}I{sub 15/2} ground state were observed when excited by CW laser radiation at 980 nm. The effect of Yb{sup 3+} on the upconversion luminescence intensity was analyzed and the upconversion luminescence mechanism was explained in terms of the energy transfer process. From this study, it confirms that the like fluorides, and germinate glasses, metal oxide nanoparticles could also be a potential host to achieve desired upconversion luminescence. -- Highlights: • Er{sup 3+}/Yb{sup 3+} co-doped bismuth molybdate nanopowder was successfully synthesized. • Infrared to visible upconversion luminescence was observed at 980 nm excitation. • Green and red emissions at 532 nm, 546 nm and 656 nm were investigated. • Bismuth molybdate could be a potential host material for upconversion luminescence.

  8. Effects of pulse width and repetition rate of pulsed laser on kinetics and production of singlet oxygen luminescence

    Directory of Open Access Journals (Sweden)

    Defu Chen

    2016-11-01

    Full Text Available Pulsed and continuous-wave (CW lasers have been widely used as the light sources for photodynamic therapy (PDT treatment. Singlet oxygen (1O2 is known to be a major cytotoxic agent in type-II PDT and can be directly detected by its near-infrared luminescence at 1270nm. As compared to CW laser excitation, the effects of pulse width and repetition rate of pulsed laser on the kinetics and production of 1O2 luminescence were quantitatively studied during photosensitization of Rose Bengal. Significant difference in kinetics of 1O2 luminescence was found under the excitation with various pulse widths of nanosecond, microsecond and CW irradiation with power of 20mW. The peak intensity and duration of 1O2 production varied with the pulse widths for pulsed laser excitation, while the 1O2 was generated continuously and its production reached a steady state with CW excitation. However, no significant difference (P>0.05 in integral 1O2 production was observed. The results suggest that the PDT efficacy using pulsed laser may be identical to the CW laser with the same wavelength and the same average fluence rate below a threshold in solution.

  9. Luminescence studies on SrMgAl 10O 17:Eu, Dy phosphor crystals

    Science.gov (United States)

    Wanjun, Tang; Donghua, Chen; Ming, Wu

    2009-02-01

    Using urea as fuel, SrMgAl 10O 17:Eu, Dy phosphor was prepared by a combustion method. Its luminescence properties under ultraviolet (UV) excitation were investigated. Pure SrMgAl 10O 17 phase was formed by urea-nitrate solution combustion synthesis at 550 °C. The results indicated that the emission spectra of SrMgAl 10O 17:Eu, Dy has one main peak at 460 nm and one shoulder peak near 516 nm, which are ascribed to two different types of luminescent Eu 2+ centers existing in the SrMgAl 10O 17 matrix crystal. The blue luminescence emission of SrMgAl 10O 17:Eu phosphors was improved under UV excitation by codoping Dy 3+ ions. The SrMgAl 10O 17:Eu phosphors showed green afterglow ( λ=516 nm) when Dy 3+ ions were doped. Dy 3+ ions not only successfully play the role of sensitizer for energy transfer in the system, but also act as trap levels and capture the free holes in the spinel blocks.

  10. Luminescence of trivalent samarium ions in silver and tin co-doped aluminophosphate glass

    Science.gov (United States)

    Jiménez, José A.; Lysenko, Sergiy; Liu, Huimin; Sendova, Mariana

    2011-06-01

    This work presents the spectroscopic properties of trivalent samarium ions in a melt-quenched aluminophosphate glass containing silver and tin. Addition of 4 mol% of each Ag 2O and SnO into the glass system with 2 mol% Sm 2O 3 results in Sm 3+ ions luminescence under non-resonant UV excitation owing to energy transfer from single silver ions and/or twofold-coordinated Sn centers. Assessment of luminescence spectra and decay dynamics suggest the energy transfer mechanism to be essentially of the resonant radiative type. Moreover, a connection between the luminescent and structural properties of the rare-earth doped glass system was demonstrated. Raman spectroscopy characterization revealed that no significant variation in the glass matrix is induced by Sm 3+ doping at the concentration employed. A comparison was made with a structural study performed on the Eu 3+ doped system (containing 2 mol% Eu 2O 3 along with 4 mol% of each Ag 2O and SnO) where the radiative energy transfer mechanism was previously established. The data appears consistent regarding the lack of variation in glass structure upon the Eu 3+ and Sm 3+ doping in connection with the dominance of the radiative transfer in the matrix. Thermal treatment of the material leads to precipitation of Ag nanoparticles of a broad size range inside the dielectric as observed by transmission electron microspcopy. Assessment of 4G 5/2 excited state decay in Sm 3+ ions shows no influence from the silver particles.

  11. Luminescence properties of uranyl-acetate species

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, Hannes; Moll, Henry [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology; Stumpf, Thorsten [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biogeochemistry

    2017-06-01

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) was applied to characterize uranium(VI)- acetate species based on their luminescence properties. In contrast to previous interpretations, no indications were detected for the existence of the 1: 3 complex.

  12. Calibration beads containing luminescent lanthanide ion complexes

    Science.gov (United States)

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  13. Application of luminescence techniques in retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Jungner, H.

    1999-01-01

    Luminescence signals measured from minerals within bricks or ceramic samples can provide information about the absorbed radiation dose. This feature has for several years been used in dating archaeological and geological samples and recently luminescence techniques have been intensively used far...... retrospective assessment of accident doses received by the population after a nuclear accident. The development of new luminescence techniques after the Chernobyl accident has considerably improved the sensitivity and precision in the evaluation of accident doses. This paper reviews the development work......, especially on optically stimulated luminescence methods for retrospective assessment of accident doses carried out at Riso National Laboratory in collaboration with the University of Helsinki as part bf a joint European Union research project. We demonstrate that doses lower than 100 mGy can be measured from...

  14. IR Bismuth active centers in optical fibers: Combined excitation-emission spectroscopy

    OpenAIRE

    Firstov, S. V.; Khopin, V. F.; Bufetov, I. A.; Firstova, E. G.; Guryanov, A. N.; Dianov, E. M.

    2011-01-01

    3D excitation-emission luminescence spectra of Bi-doped optical fibers of various compositions were measured in a wide wavelength range 450-1700 nm. Such luminescence spectra were obtained for Bi-doped pure silica and germania fibers, and for Bi-doped Al- or P-codoped silica fibers (at room and liquid nitrogen temperatures). The energy level schemes of IR bismuth active centers in pure silica and germania core fibers were derived from spectra obtained. The energy level schemes similarity of b...

  15. Luminescence Properties of RDX and HMX

    Science.gov (United States)

    1975-08-01

    than the sum of the van der Waals radii. The molecule is nonplanar in the crystal. 4 HMX can be crystallized in any of four polymorphic forms: the so...AD-AO15 538 LUMINESCENCE PROPERTIES OF RDX AND HMX Paul L. Marinkas Picatinny Arsenal Dover, New Jersey August 1975 DISTRIBUTED BY: National...Technical Information Service U. S. DEPARTMENT OF COMMERCE • i 289106. TECHNICAL REPORT 4840 LUMINESCENCE PROPERTIES, OF RDX AND HMX PAULL. MARINKAS -’-I

  16. Synthesis of luminescent ceramics from alumina nanopowder

    Science.gov (United States)

    Kortov, V.; Kiryakov, A.; Ananchenko, D.; Zvonarev, S.

    2015-11-01

    The effect of the conditions of high-temperature synthesis in a reducing medium on the density, area and cathodoluminescence of ceramics made of compacted α-Al2O3 powder is the focus of this work. The dependence of the luminescence intensity on the temperature and duration of the synthesis of ceramics is presented. The optimal parameters for synthesis of luminescent ceramics from alumina nanopowder are defined.

  17. Plasmon-enhanced optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, E. J.; Baffa, O. [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Ramos, A. P., E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Quimica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2015-10-15

    Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

  18. [Influence of parameters of ZnS film on the organic/inorganic composite luminescence devices].

    Science.gov (United States)

    Song, Ling-Yun; Cai, Chun-Feng; Liu, Bo-Zhi; Hu, Lian; Zhang, Bing-Po; Wu, Jian-Zhong; Bi, Gang; Wu, Hui-Zhen

    2014-04-01

    In the present paper, to fabricate electroluminescent devices CdSe QDs were used as active materials, TPD (N,N'-biphenyl-N,N'-bis-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine) was used as a hole transport layer, and ZnS was used as an electron transport layer. The electroluminescent properties of the organic/inorganic composite ITO/TPD/CdSe QDs/ZnS/Ag light emitting devices were studied. Both TPD and CdSe QDs thin films were spin-coated and ZnS thin films were deposited by magnetron sputtering. The surfaces of the devices are smooth. The luminescence (EL) peak of the CdSe QDs is at 580 nm which is assigned to the band-edge exciton emission. Compared to the previous EL device of ITO/ZnS/CdSe QDs/ZnS/Ag, it is seen that the new devices do not display surface state related emission peaks and EL intensity is about 10 folds that of the previous device. The enhancement of luminescence efficiency is attributed to both of the excitation of CdSe QDs by accelerated electron collision and carriers injection into QDs: (1) electrons are accelerated by the ZnS layer and collide with CdSe QDs, which excites electrons in QDs to excited states and allows them to emit photons; (2) the holes injected into QDs recombine with some of electrons excited in the QDs. The authors further studied the influence of thickness variation of ZnS on the luminescent properties. ZnS thin films are of 80, 120, and 160 nm thickness, respectively. It was found that as the thickness of ZnS increases the threshold voltage rises and EL intensity increases, but breakdown voltage decreases. The EL peak position blue shifts when the thickness of ZnS decreases. The explanation of underlying mechanism is given.

  19. Upconversion luminescence of lanthanide-doped mixed CaMoO4-CaWO4 micro-/nano-materials.

    Science.gov (United States)

    Liu, Jing; Kaczmarek, Anna M; Billet, Jonas; Van Driessche, Isabel; Van Deun, Rik

    2016-08-14

    Uniform mixed CaMoO4-CaWO4 micro-/nano-materials have been successfully synthesised by a facile hydrothermal method. The morphology of these upconversion materials could be changed to different shapes and the size could also be decreased from the micro- to nano-scale by varying the type of surfactant used. It was observed that before heat treatment, the materials show relatively weak green light emission under excitation at 975 nm, whereas after heat treatment, the intensity of the upconversion luminescence increases dramatically while the intensity of the red component decreases relatively. By adjusting the molybdate/tungstate ratio, it was found that the samples with a higher molybdate content have stronger luminescence properties. XRD measurements have been done to investigate the structure of the mixed CaMoO4-CaWO4 upconversion materials. The effect of heat treatment at different temperatures on the emission spectra and XRD patterns has also been studied. TG-DTA was used to further confirm the most suitable temperature for heat treatment. The luminescence lifetimes and CIE coordinates for these samples were also determined. Additionally it was found that Gd(3+) co-doping could further increase the upconversion luminescence from these mixed CaMoO4-CaWO4 materials. Finally, monitoring the upconversion luminescence intensity as a function of laser pump power confirmed the upconversion process to be a two-photon absorption mechanism.

  20. Luminescence investigations of rare earth doped lead-free borate glasses modified by MO (M = Ca, Sr, Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Janek, Joanna, E-mail: janek.joanna@gmail.com; Sołtys, Marta; Żur, Lidia; Pietrasik, Ewa; Pisarska, Joanna; Pisarski, Wojciech A.

    2016-09-01

    Series of lead-free borate glasses with different oxide modifiers and lanthanide ions were prepared. The effect of oxide modifiers MO (M = Ca, Sr, Ba) on spectroscopic properties of trivalent Ln{sup 3+} (Ln = Eu, Er, Pr) were systematically investigated. Especially, the luminescence spectra of Ln{sup 3+}-doped lead-free borate glasses are presented and discussed in relation to the impact of selective components (CaO, SrO and BaO). Several spectroscopic parameters, such as the fluorescence intensity ratio R/O (Eu{sup 3+}) and measured luminescence lifetimes for the {sup 5}D{sub 0} (Eu{sup 3+}), {sup 4}I{sub 13/2} (Er{sup 3+}) and {sup 1}D{sub 2} (Pr{sup 3+}) excited states of lanthanide ions were analyzed in details. The research proved that spectroscopic properties of trivalent Ln{sup 3+} depend significantly on kind of presence oxide modifiers MO (M = Ca, Sr, Ba) in glass host matrices. - Highlights: • Luminescence of Ln{sup 3+}-doped borate glasses was presented and discussed. • Effect of glass modifiers on spectroscopic properties of rare earths was studied. • Measured luminescence lifetimes of Ln{sup 3+} (Ln = Eu, Er, Pr) were analyzed. • Luminescence intensity ratios R/O (Eu{sup 3+}) were determined.

  1. Excited states 2

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 2 is a collection of papers that deals with molecules in the excited states. The book describes the geometries of molecules in the excited electronic states. One paper describes the geometries of a diatomic molecule and of polyatomic molecules; it also discusses the determination of the many excited state geometries of molecules with two, three, or four atoms by techniques similar to diatomic spectroscopy. Another paper introduces an ordered theory related to excitons in pure and mixed molecular crystals. This paper also presents some experimental data such as those invo

  2. Temporal and Remote Tuning of Piezophotonic-Effect-Induced Luminescence and Color Gamut via Modulating Magnetic Field.

    Science.gov (United States)

    Wong, Man-Chung; Chen, Li; Bai, Gongxun; Huang, Long-Biao; Hao, Jianhua

    2017-09-18

    Light-emitting materials have been extensively investigated because of their widespread applications in solid-state lighting, displays, sensors, and bioimaging. In these applications, it is highly desirable to achieve tunable luminescence in terms of luminescent intensity and wavelength. Here, a convenient physical approach of temporal and remote tuning of light-emitting wavelength and color is demonstrated, which is greatly different from conventional methods. It is shown that by modulating the frequency of magnetic-field excitation at room temperature, luminescence from the flexible composites of ZnS:Al, Cu phosphors induced by the piezophotonic effect can be tuned in real time and in situ. The mechanistic investigation suggests that the observed tunable piezophotonic emission is ascribed to the tilting band structure of the ZnS phosphor induced by magnetostrictive strain under a high frequency of magnetic-field excitation. Furthermore, some proof-of concept devices, including red-green-blue full-color displays and tunable white-light sources are demonstrated simply by frequency modulation. A new understanding of the fundamentals of both luminescence and magnetic-optics coupling is thus provided, while offering opportunities in magnetic-optical sensing, piezophotonics, energy harvesting, novel light sources, and displays. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Structural and luminescence effects of Ga co-doping on Ce-doped yttrium aluminate based phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Ayvacikli, M. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Canimoglu, A. [Nigde University, Faculty of Arts and Sciences, Physics Department, Nigde (Turkey); Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [Babes Bolyai University, Raluca Ripan Institute for Research in Chemistry, Fantanele 30, 400294 Cluj-Napoca (Romania); Barbu Tudoran, L. [Babes Bolyai University, Electronic Microscopy Centre, Clinicilor 37, 400006 Cluj Napoca (Romania); Garcia Guinea, J. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karabulut, Y. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Jorge, A. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karali, T. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Jazan University, Physics Department, P.O. Box 114, 45142 Jazan (Saudi Arabia)

    2016-05-05

    Herein, we primarily focus on luminescence spectrum measurements of various types of green emitting yttrium aluminate phosphors modified with gallium (Y{sub 3}Al{sub 5-x}Ga{sub x}O{sub 12}) synthesised by solid state reaction. The luminescent emission of samples depends on sample temperature and excitation radiation such as incident X-ray, electron and laser beam. Here, we measured radioluminescence (RL), cathodoluminescence (CL), photoluminescence (PL) along with XRD in order to clarify relationship between lattice defects and the spectral luminescence emissions. The RL and CL spectra of YAG:Ce exhibit an emission band ranging from 300 to 450 nm related to Y{sub Al} antisite defects. The broad emission band of garnet phosphors is shifted from 526 nm to 498 nm with increasing of Ga{sup 3+} content, while full width at half maximum (FWHM) of the band tends to be greater than the width of unmodified YAG:Ce garnet. Deconvolution of the spectrum reveals that three emission bands centred at 139, 234 and 294 °C occur in aluminate host garnets. - Highlights: • We present preparation of YAG:Ce{sup 3+}, Ga{sup 3+} phosphors by a solid state reaction method. • The shape and size of phosphor particles were investigated. • The luminescence properties were studied by different excitation sources.

  4. Luminescence properties of Ce3+-doped NaPrP4O12 polyphosphate

    Science.gov (United States)

    Shalapska, T.; Stryganyuk, G.; Gektin, A.; Kotlov, A.; Demchenko, P.; Voloshinovskii, A.

    2013-03-01

    Studies on the crystal structure and luminescence properties have been performed for the NaPr1-xCexP4O12 polyphosphate series. Excitation and emission spectra of Pr3+ and Ce3+ luminescence from NaPrP4O12:Ce3+ clearly reveal an efficient Pr3+ → Ce3+ energy transfer via migration over the Pr3+-sub-lattice and a nonradiative resonant transfer to the Ce3+ ions. Analysis on scintillation characteristics of the NaPr1-xCexP4O12 series shows a maximum light yield of 11 000 ± 1000 ph MeV-1 for NaPr0.99Ce0.01P4O12, proving the studied polyphosphates to be promising for application in the detection of x-ray and gamma quanta.

  5. [Comprehensive analysis of up-conversion luminescence saturation phenomena of ErYb:oxyfluoride vitroceramics].

    Science.gov (United States)

    Chen, Xiao-bo; Song, Zeng-fu

    2005-02-01

    The saturation phenomenon of the up-conversion luminescence of erbium ytterbium co-doped oxyfluoride vitroceramics (ErYb:FOV), when excited by a 966 nm diode-laser, was investigated comprehensively in the present article. A new kind of "characteristic saturation phenomenon", which results from energy diffusion, was found, i. e. the slope of logI-logP curve, the double logarithmic variation of up-conversion luminescence intensity I upon laser power P, is increased evidently toward regular multi-photon relation with the increase of laser facula. The "typical saturation phenomenon" resulting from ground state population's exhaustion has huge influence as well, which causes these logI-logP curves to bend gradually with the increase in laser power. Interestingly, this "typical saturation phenomenon" can be decreased obviously and even vanishes when the pumping laser power density is decreased enough.

  6. Creating Diversified Response Profiles from a Single Quenchometric Sensor Element by Using Phase-Resolved Luminescence

    Directory of Open Access Journals (Sweden)

    Elizabeth C. Tehan

    2015-01-01

    Full Text Available We report a new strategy for generating a continuum of response profiles from a single luminescence-based sensor element by using phase-resolved detection. This strategy yields reliable responses that depend in a predictable manner on changes in the luminescent reporter lifetime in the presence of the target analyte, the excitation modulation frequency, and the detector (lock-in amplifier phase angle. In the traditional steady-state mode, the sensor that we evaluate exhibits a linear, positive going response to changes in the target analyte concentration. Under phase-resolved conditions the analyte-dependent response profiles: (i can become highly non-linear; (ii yield negative going responses; (iii can be biphasic; and (iv can exhibit super sensitivity (e.g., sensitivities up to 300 fold greater in comparison to steady-state conditions.

  7. Luminescence studies of Eu-doped YBO{sub 3} host

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Ramya G.; Nigam, Sandeep, E-mail: snigam@barc.gov.in; Sudarsan, V., E-mail: vsudar@barc.gov.in; Vatsa, R. K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Dhabekar, B. S. [RP& AD, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2016-05-23

    Highly crystalline phase of YBO{sub 3}:Eu{sup 3+} phosphors were prepared by solid state reaction. The phosphor shows characteristic {sup 5}D{sub 0}→{sup 7}F{sub 1} (J = 1, 2, 3, 4) transition for Eu{sup 3+}. Phase purity, and emission intensity increases with increase in the annealing temperature and corresponding Eu-O charge transfer band shows blue shift in excitation spectrum. Color purity, determined in terms of R/O ratio, was found to be 1.42 (CIE color coordinates x = 0.62, y = 0.36). According to the luminescence decay analysis the {sup 5}D{sub 0} level of Eu{sup 3+} lifetime is around 5 ms and quantum efficiency is 72%. Thermo-luminescence (TL) spectra of the sample reveal three broad peaks between 80 and 240°C.

  8. Intense Raman bands and low luminescence of thin films of heme proteins on silica

    Science.gov (United States)

    Sonois, Vanessa; Bacsa, Wolfgang; Faller, Peter

    2009-08-01

    We use resonance Raman spectroscopy to study cytochrome c, hemoglobin and myoglobin from 50 μM solutions dried on a SiO 2 surface. Intense Raman spectra were observed with low luminescent background when excited at 488 nm with low laser power levels (0.6 mW) and relative short acquisition times (120 s). We estimate that 1 picogram of heme proteins can be detected. A polarization sensitive Raman band in cytochrome c near the edge of dried droplets suggests that the proteins line up in the ring deposit. This preferential orientation is suggested to contribute to the low luminescence back ground signal and to the larger Raman intensity compared to the heme proteins in powder form.

  9. Luminescent graphene quantum dots from oxidized multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Minati, L., E-mail: luminati@fbk.eu [FBK, Via Sommarive 18, Povo, 38123 Trento (Italy); Torrengo, S. [FBK, Via Sommarive 18, Povo, 38123 Trento (Italy); Maniglio, D.; Migliaresi, C. [Materials Engineering and Industrial Technologies Department, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Biotech Research Center, University of Trento, Via delle Regole 101, Mattarello, 38123 Trento (Italy); Speranza, G. [FBK, Via Sommarive 18, Povo, 38123 Trento (Italy)

    2012-11-15

    Fluorescent nano-graphene quantum dots (GQD) were isolated from oxidized carbon nanotube suspension with the aid of cysteamine. The oxidized GQD were thiol functionalized with cysteamine in presence of dicyclohexylcarbodiimide as coupling agent. The GQD chemistry and morphology were characterized by means of X-ray photoelectron spectroscopy and atomic force microscopy. The thiolated graphene quantum dots exhibit an intense luminescence (quantum yield around 10%) in the visible range with an excitation wavelength-dependent fluorescence. -- Highlights: Black-Right-Pointing-Pointer Multi-wall carbon nanotubes were oxidized by strong acids. Black-Right-Pointing-Pointer Graphene quantum dots were isolated from carbon nanotubes. Black-Right-Pointing-Pointer Graphene quantum dots were thiol functionalized by cysteamine. Black-Right-Pointing-Pointer Graphene quantum dots exhibit an intense luminescence in the visible.

  10. Multicolor tunable yellow-red emission in Eu/Er:LiNbO3 under ultraviolet and blue excitation

    Science.gov (United States)

    Zhang, Zhengyu; Tang, Xunze; Qian, Yannan; Zhang, Haiyan; Wang, Wenguang; Wang, Rui

    2017-12-01

    The ability to manipulate the multicolor luminescence will greatly enhance the scope of their applications, ranging from infrared solar cells to volumetric multiplexed bioimaging. Tuning from yellow to red emission was successfully achieved in Eu/Er:LiNbO3 under ultraviolet (UV) and blue excitation. The excitation spectra of Eu/Er:LiNbO3 monitored at 590 nm/618 nm/626 nm were studied. The CIE 1931 color coordinates showed that the emissions fell within the yellow and red region, respectively, under 376 nm and 397 nm excitation. The color coordinates shifted from yellow toward red region upon diode laser excitation of 476 nm.

  11. Luminescence properties of YVO4:Eu nanocrystals in nanoporous high-silica glass

    Science.gov (United States)

    Fan, Bin; Qi, Shimei; Zhao, Wenyu

    2018-02-01

    A feasible method was used to synthesize YVO4:Eu nanocrystals in nanoporous high-silica glass (YVOE-HSG). High-resolution transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy were used to investigate its morphology, structure, and optical properties, respectively. The Eu ions were introduced as luminescence centers into the sample YVOE-HSG. Under 291 nm excitation, the samples exhibit the characteristic transitions of Eu3+ and Eu2+. With the increase of Eu3+ doping concentration, the positions of main excitation peaks shift to long waves. The reduction of Eu3+ to Eu2+ is observed, and the chromaticity coordinates (x, y) can move from the red light to cool white and then to blue light. The efficient energy transfer from VO43- to Eu3+ and Eu2+ is confirmed. Results indicated that the sample has potential application in white light-emitting diodes under UV excitation.

  12. Characterization of trans-dioxotechnetium(V) and technetium(II)phosphine excited states and spectroelectrochemical detection of pertechnetate

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, Samuel A.; Del Negro, Andy S.; Wang, Zheming; Hubler, Timothy L.; Heineman, William R.; Seliskar, Carl J.; Sullivan, Brian P.

    2006-06-01

    We report the first examples of excited-state luminescence from technetium complexes. We have examined a series of trans-dioxo complexes of Tc(V) and a Tc(I/II) phosphine complex and compare their respective photophysical properties with the corresponding rhenium analogues. When excited with a 415 nm laser, the Tc(V) complexes luminesce in the 700-800 nm range and have excited state lifetimes in the range of several microseconds at room temperature. The low-temperature luminescence spectra of the technetium complexes have also been investigated. Distinct vibrational band progressions are resolved in the low-temperature luminescence spectra. Excited state lifetimes at 5 K vary between tens of microseconds to several milliseconds for the dioxo-technetium complexes. In addition, a previously known Tc(I) complex, [Tc(DMPE) 3]+ which has been used as a radiography imaging agent has been demonstrated in our labs to fluoresce in the visible wavelength region upon a one-electron reversible oxidation to form the Tc(II), [Tc(DMPE)3]2+ complex in aqueous solution. The luminescence of [Tc(DMPE)3]2+ was observed by illuminating the solution complex with a 404 nm excitation while performing the reversible electrochemical experiment. In a recent application, we have focused on making thin chemically-selective films for sensing radioactive technetium compounds and in this effort have developed a fluorescence-based spectroelectrochemical sensor. Characterization of the new dioxo-technetium(V) and technetium(II)phosphine excited states as well as application of the respective chromophores for use in a spectroelectrochemical sensor for pertechnetate will be discussed.

  13. Persistent luminescence in ZnGa2O4:Cr: an outstanding biomarker for in-vivo imaging

    Science.gov (United States)

    Sharma, S. K.; Bessiere, A.; Gourier, D.; Binet, L.; Viana, B.; Basavaraju, N.; Priolkar, K.; Maldiney, T.; Scherman, D.; Richard, C.

    2014-03-01

    ZnGa2O4 (ZGO) is a normal spinel. When doped with Cr3+ ions, ZGO:Cr becomes a high brightness persistent luminescence material with an emission spectrum perfectly matching the transparency window of living tissues. It allows in vivo mouse imaging with a better signal to background ratio than classical fluorescent NIR probes. The most interesting characteristic of ZGO:Cr lies in the fact that its LLP can be excited with red light, well below its band gap energy and in the transparency window of living tissues. A mechanism based on the trapping of carriers localized around a special type of Cr3+ ions namely CrN2 can explain this singularity. The antisite defects of the structure are the main responsible traps in the persistent luminescence mechanism. When located around Cr3+ ions, they allow, via Cr3+ absorption, the storage of not only UV light but also all visible light from the excitation source.

  14. Self-Assembled NaTb1-xEux(MoO4)2: Synthesis and Luminescence Properties.

    Science.gov (United States)

    Liu, Xiaoqing; Qu, Lingnan; Wang, Shuo; Li, Lv; Su, Yiguo; Wang, Xiaojing

    2016-04-01

    Novel 3D Eu3+ doped NaTb(MoO4)2 composites were successfully self-assembled by a facile hydrothermal treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectra were used to characterize the structures, morphologies and the luminescent properties of as-prepared products. Emission and excitation spectra showed that the phosphor exhibits a dominant red emission at 615 nm with excitation wavelength of 465 nm at room temperature. The emission intensity increased with the increase of Eu3+ concentrations for the investigated range of 2-10 mol% Eu3+ doping in NaTb(MoO4)2. The doping of Eu3+ results in a distorted Eu-0. cluster and enhanced luminescence intensity.

  15. Upconversion luminescence enhancement in plasmonic architecture with random assembly of metal nanodomes

    Science.gov (United States)

    Lee, Gi Yong; Jung, Kinam; Jang, Ho Seong; Kyhm, Jihoon; Han, Il Ki; Park, Byoungnam; Ju, Honglyoul; Kwon, S. Joon; Ko, Hyungduk

    2016-01-01

    We report an experimental study on the highly enhanced upconversion luminescence (UCL) of β-NaYF4:Yb3+/Er3+ nanocrystals (NCs) in a plasmonic architecture. For the architecture, we designed a thin film device composed of a thin layer of NCs capped with an upper layer of a plasmonic nanodome array (pNDA) and lower substrate of a back reflector (BR). Compared to the UCL intensity observed in a glass reference substrate, the designed plasmonic architecture exhibits distinctively strong luminescence enhanced by up to 800-fold. The intensity considerably exceeds the previously reported luminescence intensity regardless of the excitation power. We elucidated a mechanism explaining the large UCL enhancement, which quantitatively analyzes the combination of plasmonic effects as well as multiple large scattering. More importantly, we provided a detailed analysis of the Ag NDA-derived and BR-assisted plasmonic effects that contribute to an increase in the radiative decay rate and an enhancement of the absorption of incident light. The present study is expected to be beneficial for designing a thin film-based plasmonic structure with a randomized metal nanostructure for high-efficiency photovoltaic devices and infrared detectors.We report an experimental study on the highly enhanced upconversion luminescence (UCL) of β-NaYF4:Yb3+/Er3+ nanocrystals (NCs) in a plasmonic architecture. For the architecture, we designed a thin film device composed of a thin layer of NCs capped with an upper layer of a plasmonic nanodome array (pNDA) and lower substrate of a back reflector (BR). Compared to the UCL intensity observed in a glass reference substrate, the designed plasmonic architecture exhibits distinctively strong luminescence enhanced by up to 800-fold. The intensity considerably exceeds the previously reported luminescence intensity regardless of the excitation power. We elucidated a mechanism explaining the large UCL enhancement, which quantitatively analyzes the combination of

  16. Energy Migration Engineering of Bright Rare-Earth Upconversion Nanoparticles for Excitation by Light-Emitting Diodes.

    Science.gov (United States)

    Zhong, Yeteng; Rostami, Iman; Wang, Zihua; Dai, Hongjie; Hu, Zhiyuan

    2015-11-04

    A novel Nd(3+) -sensitized upconversion nanoparticle (UCNP) that can be excited by near-infrared 740 nm light-emitting diode (LED) lamps with bright upconversion luminescence is designed. Yb(3+) ion distribution is engineered to increase the energy migration efficiency. The benefit of the novel LED-excited UCNPs is demonstrated by imaging of breast cancer cells and enabling an economic handheld semiquantitative visual measurement device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Control of Green and Red Upconversion in NaYF4:Yb3+,Er3+ Nanoparticles by Excitation Modulation

    OpenAIRE

    Gainer, Christian F.; Joshua, Gihan S.; De Silva, Channa R.; Romanowski, Marek

    2011-01-01

    Control of the two strongest upconversion emission lines in NaYF4:Yb3+, Er3+ nanoparticles is demonstrated by varying the excitation repetition rate. This technique may enable new multiplexed sensing modalities based on multicolor luminescent nanoparticles, currently contemplated for biomedical imaging and diagnostics.

  18. Luminescence dating at Rose cottage cave: a progress report

    CSIR Research Space (South Africa)

    Woodborne, S

    1997-10-01

    Full Text Available Deal with infrared-stimulated luminescence and thermoluminescence dates from Rose Cottage Cave in South Africa. Discrepancy between luminescence and radiocarbon dates; Concentration of radioactive elements in sediments before and after leaching...

  19. Europium enabled luminescent nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Syamchand, S.S., E-mail: syamchand.ss@gmail.com; Sony, G., E-mail: emailtosony@gmail.com

    2015-09-15

    Lanthanide based nanoparticles are receiving great attention ought to their excellent luminescent and magnetic properties and find challenging biomedical applications. Among the luminescent lanthanide NPs, europium based NPs (Eu-NPs) are better candidates for immunoassay and imaging applications. The Eu-NPs have an edge over quantum dots (QDs) by means of their stable luminescence, long fluorescence lifetime, sharp emission peaks with narrow band width, lack of blinking and biocompatibility. This review surveys the synthesis and properties of a variety of Eu-NPs consolidated from different research articles, for their applications in medicine and biology. The exquisite luminescent properties of Eu-NPs are explored for developing biomedical applications such as immunoassay and bioimaging including multimodal imaging. The biomedical applications of Eu-NPs are mostly diagnostic in nature and mainly focus on various key analytes present in biological systems. The luminescent properties of europium enabled NPs are influenced by a number of factors such as the site symmetry, the metal nanoparticles, metal ions, quantum dots, surfactants, morphology of Eu-NPs, crystal defect, phenomena like antenna effect and physical parameters like temperature. Through this review we explore and assimilate all the factors which affect the luminescence in Eu-NPs and coil a new thread of parameters that control the luminescence in Eu-NPs, which would provide further insight in developing Eu-based nanoprobes for future biomedical prospects. - Highlights: • The review describes 14 major factors that influence the luminescence properties of europium enabled luminescent nanoparticles (Eu-NPs). • Surveys different types of europium containing nanoparticles that have been reported for their biomedical applications. • Eu-NPs are conveniently divided into four different categories, based on the type of the substrates involved. The four categories are (1) virgin Eu-substrate based NPs; (2

  20. Luminescent polymethyl methacrylate modified by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Morais, Guilherme F. [Faculdade de Tecnologia de Sao Paulo (FATEC-ZL), Sao Paulo, SP (Brazil); Forster, Pedro L.; Marchini, Leonardo G.; Lugao, Ademar B.; Parra, Duclerc F., E-mail: dfparra@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Thin films of PMMA (polymethyl methacrylate) doped with luminescent complexes have been studied and developed for applications in advanced technologies. The problem of stability of these films is focused in this study. Films stabilization by reaction with fluorinated monomers is a recent study that aims to increase its luminescence properties for long time. The films were prepared by dilution of PMMA in chloroform with addition of europium complex, at proportion of 5% by weight of polymer. The luminescent polymer films were obtained by casting. Thin layer slides of the film were separated in three parts. One was reacted with fluorinated monomers (C{sub 2}F{sub 4}) in closed reactor for 48 hours. A second part was reacted with C{sub 2}F{sub 4} after irradiation in gamma source at 5 kGy in simultaneous process. The last part was used as obtained. The luminescent polymer matrices were characterized using the techniques of infrared (FTIR) and thermogravimetry (TGA/DTG). Samples of the films were, in presence of fluorine monomers, exposed to ionizing radiation in dose of 5 kGy, for react with monomers in the doped polymer surface. In this case the effects of radiation were evaluated on the luminescent films. (author)

  1. [Influence of aflatoxin on Vibrio fischeri luminescence].

    Science.gov (United States)

    Li, Xiang; Pan, Li; Wang, Bin

    2011-12-01

    In the present study, we aim to evaluate the inhibitory effect of aflatoxin on Vibrio fischeri luminescence. V. fischeri culture is treated with aflatoxin or the culture broth of aflatoxin-producing strains, and the luminescence intensity of V. fischeri is detected to analyze the influence of aflatoxin on V. fischeri. The logarithmic value of aflatoxin concentration and the decrease ratio of V. fischeri luminescence is in a linear relationship. Based on the regression equation between aflatoxin concentration and luminescence decrease of V. fischeri, the toxin-producing status of different microbes can be detected quickly and exactly: all of six tested Aspergillus flavus strains show toxigenicity to V. fischeri, and their toxin yield reached 14.94 mg/L - 46.45 mg/L (represented by aflatoxin concentration), while the tested Aspergillus oryzae shows no toxigenicity. The above data showed that the luminescence change of V. fischeri could exactly reflect the capability of various microbes to produce toxin (especially aflatoxin), which provided a new clue for rapid detection of aflatoxin in industrial and agricultural production and could be developed as a potential method for aflatoxin assay.

  2. High-Temperature Luminescence Quenching of Colloidal Quantum Dots

    OpenAIRE

    Zhao, Y.; Riemersma, C.; Pietra, F; de Mello Donega, C.; Meijerink, A.

    2012-01-01

    Thermal quenching of quantum dot (QD) luminescence is important for application in luminescent devices. Systematic studies of the quenching behavior above 300 K are, however, lacking. Here, high-temperature (300–500 K) luminescence studies are reported for highly efficient CdSe core–shell quantum dots (QDs), aimed at obtaining insight into temperature quenching of QD emission. Through thermal cycling (yoyo) experiments for QDs in polymer matrices, reversible and irreversible luminescence quen...

  3. Visible light stimulating dual-wavelength emission and O vacancy involved energy transfer behavior in luminescence for coaxial nanocable arrays

    Science.gov (United States)

    Yang, Lei; Dong, Jiazhang; Jiang, Zhongcheng; Pan, Anlian; Zhuang, Xiujuan

    2014-06-01

    We report a strategy to investigate O vacancy (VO) involved energy transfer and dual-wavelength yellow emission in coaxial nanocable. By electric field deposition and subsequent sol-gel template approach, ZnO:Tb/Y2O3:Eu coaxial nanocable arrays are synthesized. After visible light excitation, system is promoted to O vacancy charge transfer state of VO(0/+). In the following cross relaxation, energy transfer from VO to the excitation energy level of Tb3+ in ZnO:Tb core area. While in Y2O3:Eu shell area, energy transfer to the excitation energy level of Eu3+. Subsequently, dual-wavelength emission is observed. By constructing nanocable with dual-wavelength emission, yellow luminescence is obtained. Adjust doping concentration of Eu3+ or Tb3+ in the range of 0.01-0.05, chromaticity coordinates of ZnO:Tb/Y2O3:Eu nanocable stably stays at yellow region in color space except ZnO:Tb0.01/Y2O3:Eu0.01. As Vo states act as media in energy transfer process in nanocablers, visible light can stimulate dual-wavelength emissions. Yellow luminescent nanocable arrays will have great applications in light-emitting diode luminescence.

  4. Microstructure and luminescent properties of Ce:Lu2SiO5 ceramic scintillator by spark plasma sintering

    Science.gov (United States)

    Xie, Jianjun; Shi, Ying; Fan, Lincong; Xu, Zhibin

    2013-02-01

    Spark plasma sintering (SPS) processing was employed to fabricate cerium (Ce3+) ions doped lutetium silicate (Lu2SiO5) translucent scintillation ceramics. Polycrystalline Ce:Lu2SiO5 ceramic bulks were densified from as-prepared powder by spark plasma sintering at 1350 °C for 5 min under pressure of 50 MPa. Translucent monolithic Ce:Lu2SiO5 ceramic specimen was obtained with excellent luminescent characteristics after being annealed in air at 1000 °C for 15 h. Under 360 nm UV excitation, a broad emission peak centered at about 425 nm was detected for Ce:Lu2SiO5 ceramic. The luminescence intensity of annealed ceramic sample (doped by 0.5 mol% Ce3+) was 3 times greater than that of BGO single crystal under X-ray excitation. The decay constant under γ-ray excitation of Cs-137 radioactive source was measured to 44.36 ns. The good luminescent characteristics made Ce:Lu2SiO5 polycrystalline ceramics a promising scintillator candidate with high performance for radiation detection in future.

  5. Two-photon luminescence and stimulated emission depletion with gold nanorods by a single wavelength

    Science.gov (United States)

    Chen, Jianling; You, Minghai; Peng, Yiru; Yang, Hongqin; Xie, Shusen

    2017-06-01

    Single-wavelength two photon STED technique simplifies common STED setup, and decreases the cost of the system. However, this technique limits the fluorescent dye to a few kinds. Because the dye should be excited and depleted by the same single wavelength laser. And the gold nanorods can be excited by near-infrared pulsed laser and produces two photon luminescence, which is brighter than general two-photon autofluorescence by three orders. We found that the gold nanorods can also be depleted by near-infrared pulsed laser. We studied the stimulated emission depletion of gold nanorods with a single wavelength laser in the near infrared. Two photon luminescence was excited with a femtosecond pulse, then depleted by stimulated emission with a stretched pulse. The depletion efficiency with different wavelength was measured to pick out the optimal wavelength. We showed that this method can be applied to super-resolved STED microscopy, which combines the high brightness of the nanorods and the simplicity of the single-wavelength STED system.

  6. Optical characterization of luminescent silicon nanocrystals embedded in glass matrices

    Energy Technology Data Exchange (ETDEWEB)

    Debieu, Olivier

    2008-12-16

    Interstellar dust in nebulae and in the Diffuse Interstellar Medium (DISM) of galaxies contains a component which exhibits efficient visible-near infrared luminescence ranging from 500 to 1000 nm, known as Extended Red Emission (ERE). Silicon nanocrystals (nc-Si) are discussed as possible carriers of the ERE. We employed the accelerator facilities of the Institute of Solid State Physics of the University of Jena to implant Si ions into fused silica windows. An excess concentration of silicon atoms is thus produced in the host SiO{sub 2} matrix which, by applying an annealing at 1100 C, condensates to silicon nanoparticles and crystallizes. Although the condensation and crystallization occur after an annealing of one minute,10, 15 the samples were annealed during one hour in order to well-passivate the nc-Si, that means, to reduce effectively the number of Si-dangling bonds at the nc-Si surface that are efficient non-radiative recombination centers. 10, 16 Upon excitation with UV light, most of our nc-Si/SiO{sub 2} samples revealed strong PL. We implanted into our luminescent nc-Si/SiO{sub 2} systems other atomic elements, as for instance magnesium and calcium, which form silicates if their oxide is combined with SiO{sub 2}. The purpose is to simulate the conditions for silicates containing nc-Si. In order to understand the effect of the incorporation of foreign atoms on the PL properties of our nc-Si/SiO{sub 2} systems, we proceeded to similar experiments with Er and Ge. As has been demonstrated by several authors, 17, 18 the presence of nc-Si in a glass matrix enhances considerably the emission of Er{sup 3+} ions at 1.536{mu}m. At the same time, the PL of nc-Si is considerably quenched. Since the solubility of Er in crystalline silicon is about 2 orders of magnitude lower than in SiO{sub 2}, the optically active Er{sup 3+} ions are believed to be localized outside the nc-Si core, demonstrating that ions present in the host SiO{sub 2} matrix influence the PL

  7. Microwave synthesis of non-crystalline BCNO phosphors using thiourea as nitrogen source and their tunable luminescence

    Science.gov (United States)

    Chen, Jingjing; Zhao, Yang; Mao, Zhiyong; Wang, Dajian; Bie, Lijian

    2017-02-01

    Thiourea was employed as nitrogen source to synthesize BCNO phosphors by a simple microwave heating route. The phase structure, chemical composition, and the dependence of photoluminescent properties on the carbon content and incident excitation light for as-prepared BCNO phosphors were investigated in detail. Non-crystalline powder samples constituted by B, C, N, O elements with a slight of S dopant were identified for the prepared BCNO phosphors. Tunable luminescence induced by carbon content and incident excitation light implies the obtained non-crystalline BCNO phosphors could be used as an excellent candidate for LED conversion phosphor.

  8. High-Temperature Luminescence Quenching of Colloidal Quantum Dots

    NARCIS (Netherlands)

    Zhao, Y.|info:eu-repo/dai/nl/355358352; Riemersma, C.; Pietra, F|info:eu-repo/dai/nl/355358395; de Mello Donega, C.|info:eu-repo/dai/nl/125593899; Meijerink, A.|info:eu-repo/dai/nl/075044986

    2012-01-01

    Thermal quenching of quantum dot (QD) luminescence is important for application in luminescent devices. Systematic studies of the quenching behavior above 300 K are, however, lacking. Here, high-temperature (300–500 K) luminescence studies are reported for highly efficient CdSe core–shell quantum

  9. Excited states 4

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 4 is a collection of papers that deals with the excited states of molecular activity. One paper investigates the resonance Raman spectroscopy as the key to vibrational-electronic coupling. This paper reviews the basic theory of Raman scattering; it also explains the derivation of the Raman spectra, excitation profiles, and depolarization ratios for simple resonance systems. Another paper reviews the magnetic properties of triplet states, including the zero-field resonance techniques, the high-field experiments, and the spin Hamiltonian. This paper focuses on the magnetic

  10. Nuclear expansion with excitation

    Energy Technology Data Exchange (ETDEWEB)

    De, J.N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Samaddar, S.K. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Vinas, X. [Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Centelles, M. [Departament d' Estructura i Constituents de la Materia, Facultat de Fisica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)]. E-mail: mario@ecm.ub.es

    2006-07-06

    The expansion of an isolated hot spherical nucleus with excitation energy and its caloric curve are studied in a thermodynamic model with the SkM{sup *} force as the nuclear effective two-body interaction. The calted results are shown to compare well with the recent experimental data from energetic nuclear collisions. The fluctuations in temperature and density are also studied. They are seen to build up very rapidly beyond an excitation energy of {approx}9 MeV/u. Volume-conserving quadrupole deformation in addition to expansion indicates, however, nuclear disassembly above an excitation energy of {approx}4 MeV/u.

  11. R. f. -sputtered luminescent rare earth and yttrium oxysulphide films

    Energy Technology Data Exchange (ETDEWEB)

    Sella, C.; Martin, J.C.; Charreire, Y.

    1982-04-16

    The rare earth and yttrium oxysulphides form a family of highly luminescent materials and are of practical importance for cathode ray tubes and other visual display devices. The conventional screens are composed of a phosphor powder and have limited brightness, resolution and contrast. The brightness is limited by heating of the phosphor and poor thermal conductivity between the particles and the substrate. The resolution is limited by the particle size. The contrast is reduced by a high diffuse reflectivity of ambient light. Continuous thin films are not subject to these limitations. In previous attempts to produce such films by classical evaporation or sputtering techniques most of the luminous efficiency of the material was lost. When r.f. sputtering was carried out in standard vacuum equipment (10/sup -6/ Torr), a sulphur deficiency in the films was observed owing to the residual oxygen pressure. To overcome these difficulties, we used a new sputtering system designed for high purity deposition and mounted in an ultrahigh vacuum unit. Two methods were used to prepare Y/sub 2/O/sub 2/S and La/sub 2/O/sub 2/S luminescent films activated by Eu/sup 3 +/ (red) and by Tb/sup 3 +/ (green): (1) deposition from a pure oxysulphide target with subsequent treatment in H/sub 2/S between 700 and 850/sup 0/C; (2) deposition from a mixed sulphide-oxysulphide target with subsequent treatment in argon or an Ar-H/sub 2/ mixture between 500 and 850/sup 0/C. All films were investigated by X-ray diffraction, scanning and transmission electron microscopies, cathodoluminescence and photoluminescence excited with a pulsed laser.

  12. Photo-Induced Assembly of a Luminescent Tetraruthenium Square.

    Science.gov (United States)

    Laramée-Milette, Baptiste; Nastasi, Francesco; Puntoriero, Fausto; Campagna, Sebastiano; Hanan, Garry S

    2017-11-21

    Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl RuII precursor into a discrete molecular square. Diffusion-ordered NMR spectroscopy confirmed the synthesis of a higher volume species, while the identity of the species was established by high-resolution mass spectrometry and single-crystal X-ray diffraction studies. The self-assembled square is not obtained by classical thermal techniques in similar conditions, but is obtained only by light-irradiation. The tetraruthenium square has an excited-state lifetime (135 ns), 40 times that of its mononuclear precursor and its luminescence quantum yield (1.0 %) is three orders of magnitude higher. These remarkable luminescence properties are closely related to the relatively rigid square structure of the tetraruthenium assembly, as suggested by slow radiationless decay and transient absorption spectroscopy. The results described herein are a rare example of photo-induced assembly and dis-assembly processes, and can open the way to a new avenue in supramolecular chemistry, leading to the preparation of structurally organized supermolecules by photochemical techniques. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effect of CH{sub 3}OH on the luminescent properties of the [Zn(sfdb)(bpy)(H{sub 2}O)]{sub n} · 0.5nCH{sub 3}OH metal–organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xuedan; Liu, Zhiqiao; Shi, Yantao [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Hao, Juanyuan [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Panjin 124221 (China); Qiu, Jieshan [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Hao, Ce, E-mail: haoce@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Panjin 124221 (China)

    2015-01-13

    Graphical abstract: - Highlights: • TDDFT method is used to study the excited state hydrogen bonding. • The origin of the luminescence of the MOF is LLCT. • The hydrogen bond between CH{sub 3}OH and MOF leads to enhanced luminescence. - Abstract: The influence of CH{sub 3}OH solvent on the luminescent properties of the [Zn(sfdb)(bpy)(H{sub 2}O)]{sub n} · 0.5nCH{sub 3}OH (sfdb = 4,4-sulfonyldibenzoic acid, bpy = 2,2-bipyridine) metal–organic framework (MOF) was investigated by considering the hydrogen bond between CH{sub 3}OH and [Zn(sfdb)(bpy)(H{sub 2}O)]{sub n} in an electronically excited state using density functional theory and time-dependent density functional theory methods. The calculated geometry, infrared spectrum, and UV–vis spectrum in the ground state are consistent with the experimental results. The frontier molecular orbitals and electronic configuration indicated that the origin of the luminescence is ligand-to-ligand charge transfer rather than ligand-to-metal charge transfer, as has been previously proposed. We found that the O3⋯H11 hydrogen bond is weaker in the excited state than in the ground state, and the weaker hydrogen bond in the electronically excited state should enhance the luminescence. The results show that the CH{sub 3}OH solvent changes the luminescence properties of [Zn(sfdb)(bpy)(H{sub 2}O)]{sub n}, which provides potential opportunities for the design of diverse luminescent MOFs.

  14. Enhanced Luminescent Properties in Tm3+/Dy3+ Co-doped Transparent Phosphate Glass Ceramic

    OpenAIRE

    Yao L. Q.; Chen G. H.; Zhong H. J.; Cui S. C.; Li F; Gan J.Y.

    2016-01-01

    Novel Tm3+/Dy3+ co-doped phosphate glass and glass ceramic samples for white light emitting diodes were prepared by melt quenching method. Under 353 nm excitation, the colors of the luminescence of the glass and glass ceramic samples are white. The CIE chromaticity coordinates (0.338, 0.328) of the emission from the glass ceramic is close to the standard white-light illumination (0.333, 0.333). Compared to the glass, the fluorescence intensity in the glass ceramic is greatly enhanced.

  15. Multicolour optical coding from a series of luminescent lanthanide complexes with a unique antenna.

    Science.gov (United States)

    Wartenberg, Nicolas; Raccurt, Olivier; Bourgeat-Lami, Elodie; Imbert, Daniel; Mazzanti, Marinella

    2013-03-04

    The bis-tetrazolate-pyridine ligand H(2)pytz sensitises efficiently the visible and/or near-IR luminescence emission of ten lanthanide cations (Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb). The Ln(III) complexes present sizeable quantum yields in both domains with a single excitation source. The wide range of possible colour combinations in water, organic solvents and the solid state makes the complexes very attractive for labelling and encoding. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Glucose optical fibre sensor based on a luminescent molecularly imprinted polymer

    Science.gov (United States)

    Elosua, C.; Wren, S. P.; Sun, T.; Arregui, F. J.; Grattan, Kenneth T. V.

    2015-09-01

    An optrode able to detect glucose dissolved in water has been implemented. The device is based on the luminescence emission of a Molecularly Imprinted Polymer synthesized specifically for glucose detection, therefore its intensity changes in presence of glucose. This sensing material is attached onto a cleaved ended polymer-clad optical fibre and it is excited by light via 1x2 fibre coupler. The reflected fluorescence signal increases when it is immersed into glucose solutions and recovers to the baseline when it is dipped in ultrapure water. This reversible behaviour indicates the measurement repeatability of using such a glucose sensor.

  17. Luminescent Ag12-metallothionein: dependence of emission intensity on silver-thiolate cluster formation.

    Science.gov (United States)

    Stillman, M J; Zelazowski, A J; Gasyna, Z

    1988-11-21

    We report the observation of emission intensity at 77 K that is a function of Ag(I)-thiolate bonds formation within the protein metallothionein. The emission characteristics (a large, 250 nm, Stokes shift and long emission lifetime) suggests that the transition occurs from the excited triplet state. The emission intensity and circular dichroism both indicate that silver(I) clusters form with stoichiometric ratios of 12 Ag(I) to the 20 thiolate sulfur groups that are present in the protein. These data are the first to show that Ag(I)-metallothionein complexes are luminescent and that a specific Ag12-MT species forms.

  18. Order and disorder around Cr$^{3+}$ in chromium doped persistent luminescence AB$_2$O$_4$ spinels

    OpenAIRE

    Basavaraju, Neelima; Priolkar, Kaustubh R.; Gourier, Didier; Bessière, Aurélie; Viana, Bruno

    2015-01-01

    X-ray absorption near edge structure (XANES) spectroscopy technique is used to better understand the charging and decharging processes of the persistent luminescence in the Cr$^{3+}$ doped AB$_2$O$_4$ spinels (A = Zn, Mg and B = Ga and Al) with low photon energy excitation by visible light. Cr K edge XANES spectra have been simulated for different near neighbour environments around the Cr$^{3+}$ recombination centres and compared with the experimental curve. In Cr$^{3+}$:ZnGa$_2$O$_4$ compoun...

  19. Rare Earth Luminescence in Phosphogypsum Waste Produced From Phosphate Ore Processing

    Directory of Open Access Journals (Sweden)

    Ines Hammas Nasri

    2015-06-01

    Full Text Available Luminescence properties of rare earth elements (Eu3+, Sm3+ and Ce3+ were investigated in phosphogypsum waste produced from the phosphoric acid manufacture. The presence of these elements was already confirmed after analysis of the phosphogypsum sample by inductively coupled plasma mass spectrometry, which showed total rare earths content about 350 ppm. The principal aim of this work is to use the photoluminescence technique for identifying 4f ions by the mutual relationship between excitation and emission spectra.  The obtained spectra may be used then as reliable references for monitoring rare earth elements during their extraction from phosphogypsum, any time that the inductively coupled plasma mass spectrometry is inapplicable.To find the most convenient conditions for observing Eu3+ emissions, a powder of calcium sulfate doped with europium (CaSO4: Eu (1% was synthesized. After comparison with the emission and excitation spectra of the synthetic gypsum, it was pointed out that excitation of the phosphogypsum selectively at 466 nm is the most suitable for observing Eu3+ emissions. These latter were obtained at around 556 nm and 603 nm.  Based on literature data, Sm3+ and Ce3+ emissions in the phosphogypsum were identified. Sm3+ lines were obtained at 567 nm and 602 nm after a selective excitation at the 4G5/2-6H7/2 transition (404 nm. Whereas cerium luminescence was only observed after calcination of the phosphogypsum sample at 900°C. Ce3+ emissions were obtained at around 305 nm and 326 nm after excitation of the calcined phosphogypsum at 254 nm. The effect of phosphogypsum impurities on the lifetime of rare earths emissions was also discussed.

  20. Luminescence and the solid state

    CERN Document Server

    Ropp, Richard C

    2013-01-01

    Since the discovery of the transistor in 1948, the study of the solid state has been burgeoning. Recently, cold fusion and the ceramic superconductor have given cause for excitement. There are two approaches possible to this area of science, namely, that of solid state physics and solid state chemistry, although both overlap extensively. The former is more concerned with electronic states in solids (including electromagnetics) whereas the latter is more concerned with interactions of atoms in solids. The area of solid state physics is well documented, however, there are very few texts which de

  1. Development of an optically-based tension-indicating implanted orthopedic screw with a luminescent spectral ruler

    Science.gov (United States)

    Ravikumar, Nakul; Rogalski, Melissa M.; Benza, Donny; Lake, Joshua; Urban, Matthew; Pelham, Hunter; Anker, Jeffrey N.; DesJardins, John D.

    2017-03-01

    An orthopaedic screw was designed with an optical tension-indicator to non-invasively quantify screw tension and monitor the load sharing between the bone and the implant. The screw both applies load to the bone, and measures this load by reporting the strain on the screw. The screw contains a colorimetric optical encoder that converts axial strain into colorimetric changes visible through the head of the screw, or luminescent spectral changes that are detected through tissue. Screws were tested under cyclic mechanical loading to mimic in-vivo conditions to verify the sensitivity, repeatability, and reproducibility of the sensor. In the absence to tissue, color was measured using a digital camera as a function of axial load on a stainless steel cannulated (hollow) orthopedic screw, modified by adding a passive colorimetric strain gauge through the central hole. The sensor was able to quantify clinically-relevant bone healing strains. The sensor exhibited good repeatability and reproducibility but also displayed hysteresis due to the internal mechanics of the screw. The strain indicator was also modified for measurement through tissue by replacing the reflective colorimetric sensor with a low-background X-ray excited optical luminescence signal. Luminescent spectra were acquired through 6 mm of chicken breast tissue. Overall, this research shows feasibility for a unique device which quantifies the strain on an orthopedic screw. Future research will involve reducing hysteresis by changing the mechanism of strain transduction in the screw, miniaturizing the luminescent strain gauge, monitoring bending as well as tension, using alternative luminescent spectral rulers based upon near infrared fluorescence or upconversion luminescence, and application to monitoring changes in pretension and load sharing during bone healing.

  2. Principles of responsive lanthanide-based luminescent probes for cellular imaging.

    Science.gov (United States)

    Thibon, Aurore; Pierre, Valérie C

    2009-05-01

    The advent of chemical tools for cellular imaging--from organic dyes to green fluorescent proteins--has revolutionized the fields of molecular biology and biochemistry. Lanthanide-based probes are a new player in this area, as the last decade has seen the emergence of the first responsive luminescent lanthanide probes specifically intended for imaging cellular processes. The potential of these probes is still undervalued by the scientific community. Indeed, this class of probes offers several advantages over organic dyes and fluorescent proteins. Their very long luminescence lifetimes enable quantitative spatial determination of the intracellular concentration of an analyte through time-gating measurements. Their emission bands are very narrow and do not overlap, enabling the simultaneous use of multiple lanthanide probes to quantitatively detect several analytes without cross-interference. Herein we describe the principles behind the development of this class of probes. Sensors for a desired analyte can be designed by rationally manipulating the parameters that influence the luminescence of lanthanide complexes. We will discuss sensors based on varying the number of inner-sphere water molecules, the distance separating the antenna from the lanthanide ion, the energies of excited states of the antenna, and PeT switches.

  3. CMOS Imaging of Pin-Printed Xerogel-Based Luminescent Sensor Microarrays.

    Science.gov (United States)

    Yao, Lei; Yung, Ka Yi; Khan, Rifat; Chodavarapu, Vamsy P; Bright, Frank V

    2010-12-01

    We present the design and implementation of a luminescence-based miniaturized multisensor system using pin-printed xerogel materials which act as host media for chemical recognition elements. We developed a CMOS imager integrated circuit (IC) to image the luminescence response of the xerogel-based sensor array. The imager IC uses a 26 × 20 (520 elements) array of active pixel sensors and each active pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. The imager includes a correlated double sampling circuit and pixel address/digital control circuit; the image data is read-out as coded serial signal. The sensor system uses a light-emitting diode (LED) to excite the target analyte responsive luminophores doped within discrete xerogel-based sensor elements. As a prototype, we developed a 4 × 4 (16 elements) array of oxygen (O2) sensors. Each group of 4 sensor elements in the array (arranged in a row) is designed to provide a different and specific sensitivity to the target gaseous O2 concentration. This property of multiple sensitivities is achieved by using a strategic mix of two oxygen sensitive luminophores ([Ru(dpp)3]2+ and ([Ru(bpy)3]2+) in each pin-printed xerogel sensor element. The CMOS imager consumes an average power of 8 mW operating at 1 kHz sampling frequency driven at 5 V. The developed prototype system demonstrates a low cost and miniaturized luminescence multisensor system.

  4. The use of unburned propellant powder for shooting-distance determination. Part I: Infrared luminescence.

    Science.gov (United States)

    Hofer, Rolf; Graf, Stefan; Christen, Stephan

    2017-04-01

    Unburned propellant powder particles in gunshot residue (GSR) were detected at near infrared by optical excitation in the visible wavelength range. A series of ammunition (different brands and different manufacturers) was analyzed concerning the luminescence of their propellant. Shooting target samples with different shooting distances were produced on standard textile tissue and analyzed with this optical infrared inspection. The number of luminescent GSR particles per area was measured and curves with particle density vs. shooting distance were drawn. The method was applied on three ammunition types with different particle morphology shot with a pistol and one ammunition type shot with a revolver. The shooting series performed with the revolver showed a large particle density variation within the samples of identical shooting distances. In this case, the ratio of the amount of particles within the area around the bullet hole and within a ring with a defined distance from the bullet hole was calculated. These data resulted in measures with much lower standard deviations, which is a prove that the distribution pattern depends on the shooting distance and not on the amount of GSR particles. It has been shown, that imaging of target tissue with the aid of infrared luminescence is an easy, fast, reproducible and non-destructive method for shooting-distance determination. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Order and disorder around Cr(3+) in chromium doped persistent luminescent AB2O4 spinels.

    Science.gov (United States)

    Basavaraju, Neelima; Priolkar, Kaustubh R; Gourier, Didier; Bessière, Aurélie; Viana, Bruno

    2015-04-28

    The X-ray absorption near edge structure (XANES) spectroscopy technique is used to better understand the charging and decharging processes of the persistent luminescence in the Cr(3+)doped AB2O4 spinels (A = Zn, Mg and B = Ga and Al) with low photon energy excitation by visible light. Cr K edge XANES spectra have been simulated for different near neighbour environments around the Cr(3+) recombination centres and compared with the experimental curve. In the Cr(3+):ZnGa2O4 compound, the Cr(3+) local structure corresponds mostly to that of a normal spinel (∼70%), while the rest comprises of a distorted octahedral environment arising from cationic site inversion and a contribution from chromium clustering. This local structure is considerably different in Cr(3+):MgGa2O4 and Cr(3+):ZnAl2O4, where, for both cases, chromium clustering represents the main contribution. The strong correlation between the intensity of persistent luminescence and the percentage of Cr in clusters leads us to infer that the presence of Cr clusters is responsible for the decrease of the intensity of the visible light induced persistent luminescence in the Cr(3+) doped AB2O4 spinels.

  6. 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.

  7. PROPERTIES OF Eu3+ LUMINESCENCE IN THE MONOCLINIC Ba2MgSi2O7

    Directory of Open Access Journals (Sweden)

    Shansh an Yao

    2011-09-01

    Full Text Available Red-emitting phosphors Ba2-xMgSi2O7: Eux3+ was prepared by combustion-assisted synthesis method and an efficient red emission under near-ultraviolet (UV was observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometer. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0 → 7F2 transitions of Eu3+. The phosphor has two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively. The effect of Eu3+ concentration on the emission spectrum of Ba2MgSi2O7:Eu3+ phosphor was studied. The results showed that the emission intensity increased with increasing Eu3+ concentration, and then decreased because of concentration quenching. The critical quenching concentration of Eu3+ in Ba2MgSi2O7: Eu3+ phosphor is about 0.05 mol. The mechanism of concentration quenching of Ba2MgSi2O7: Eu3+ luminescence is energy transfer between Eu3+ ions casued by the dipole-dipole interaction.

  8. The Intersection of CMOS Microsystems and Upconversion Nanoparticles for Luminescence Bioimaging and Bioassays

    Directory of Open Access Journals (Sweden)

    Liping Wei

    2014-09-01

    Full Text Available Organic fluorophores and quantum dots are ubiquitous as contrast agents for bio-imaging and as labels in bioassays to enable the detection of biological targets and processes. Upconversion nanoparticles (UCNPs offer a different set of opportunities as labels in bioassays and for bioimaging. UCNPs are excited at near-infrared (NIR wavelengths where biological molecules are optically transparent, and their luminesce in the visible and ultraviolet (UV wavelength range is suitable for detection using complementary metal-oxide-semiconductor (CMOS technology. These nanoparticles provide multiple sharp emission bands, long lifetimes, tunable emission, high photostability, and low cytotoxicity, which render them particularly useful for bio-imaging applications and multiplexed bioassays. This paper surveys several key concepts surrounding upconversion nanoparticles and the systems that detect and process the corresponding luminescence signals. The principle of photon upconversion, tuning of emission wavelengths, UCNP bioassays, and UCNP time-resolved techniques are described. Electronic readout systems for signal detection and processing suitable for UCNP luminescence using CMOS technology are discussed. This includes recent progress in miniaturized detectors, integrated spectral sensing, and high-precision time-domain circuits. Emphasis is placed on the physical attributes of UCNPs that map strongly to the technical features that CMOS devices excel in delivering, exploring the interoperability between the two technologies.

  9. The intersection of CMOS microsystems and upconversion nanoparticles for luminescence bioimaging and bioassays.

    Science.gov (United States)

    Wei, Liping; Doughan, Samer; Han, Yi; DaCosta, Matthew V; Krull, Ulrich J; Ho, Derek

    2014-09-10

    Organic fluorophores and quantum dots are ubiquitous as contrast agents for bio-imaging and as labels in bioassays to enable the detection of biological targets and processes. Upconversion nanoparticles (UCNPs) offer a different set of opportunities as labels in bioassays and for bioimaging. UCNPs are excited at near-infrared (NIR) wavelengths where biological molecules are optically transparent, and their luminesce in the visible and ultraviolet (UV) wavelength range is suitable for detection using complementary metal-oxide-semiconductor (CMOS) technology. These nanoparticles provide multiple sharp emission bands, long lifetimes, tunable emission, high photostability, and low cytotoxicity, which render them particularly useful for bio-imaging applications and multiplexed bioassays. This paper surveys several key concepts surrounding upconversion nanoparticles and the systems that detect and process the corresponding luminescence signals. The principle of photon upconversion, tuning of emission wavelengths, UCNP bioassays, and UCNP time-resolved techniques are described. Electronic readout systems for signal detection and processing suitable for UCNP luminescence using CMOS technology are discussed. This includes recent progress in miniaturized detectors, integrated spectral sensing, and high-precision time-domain circuits. Emphasis is placed on the physical attributes of UCNPs that map strongly to the technical features that CMOS devices excel in delivering, exploring the interoperability between the two technologies.

  10. Site symmetry and crystal field of Ce{sup 3+} luminescent centres in KMgF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yamaga, M. [Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu (Japan); Honda, M.; Kawamata, N. [Faculty of Science, Naruto University of Education, Naruto (Japan); Fujita, T.; Shimamura, K.; Fukuda, T. [Institute for Materials Research, Tohoku University, Sendai (Japan)

    2001-04-09

    The electron-spin resonance (ESR) spectra of Ce{sup 3+} in KMgF{sub 3} observed at low temperatures (<20 K) show that two tetragonal and two orthorhombic Ce{sup 3+} centres exist in the absence of a cubic centre. These Ce{sup 3+} centres are strongly associated with substitution of Ce{sup 3+} ions for K{sup +} ions with K{sup +}-ion vacancies at three different sites and for a Mg{sup 2+} ion with a vacancy of the nearest neighbour Mg{sup 2+} ion along the [101] direction as charge compensators. The optical absorption spectrum of Ce{sup 3+} in KMgF{sub 3} measured at room temperature consists of two intense broadbands with peaks at 229 and 237 nm, and two weak bands with peaks at 203 and 211 nm corresponding to the transition from the ground state {sup 2}F{sub 5/2} to the 5d{sup 1} excited states of Ce{sup 3+}. The Ce{sup 3+} luminescence spectrum excited at 229 or 237 nm at room temperature is composed of broadbands with double peaks at 265 and 282 nm, which are due to the ground-state splitting between {sup 2}F{sub 5/2} and {sup 2}F{sub 7/2}. The peak of the weak luminescence band excited at a tail (250-280 nm) of the intense absorption bands is shifted to lower energy. The intense and weak Ce{sup 3+} luminescence bands are assigned to Ce{sup 3+} ions substituting for K{sup +} ions away from and near to K{sup +}-ion vacancies, respectively. The luminescence from Ce{sup 3+} ions substituting for Mg{sup 2+} ions could not be observed at room temperature. (author)

  11. Luminescent Mycena: new and noteworthy species

    Science.gov (United States)

    Dennis E. Desjardin; D. Jean Lodge; Cassius V. Stevani; Eiji. Nagasawa

    2010-01-01

    Seven species of Mycena are reported as luminescent, representing specimens collected in Belize, Brazil, Dominican Republic, Jamaica, Japan (Bonin Islands), Malaysia (Borneo) and Puerto Rico. Four of them represent new species (Mycena luxaeterna, M. luxarboricola, M. luxperpetua, M. silvaelucens) and three represent new reports of...

  12. Studies of positron induced luminescence from polymers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Hulett, L.D. Jr.; Lewis, T.A. [Oak Ridge National Lab., TN (United States); Tolk, N.H. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Physics and Astronomy

    1994-06-01

    Light emission from polymers (anthracene dissolved in polystryrene) induced by low-energy positrons and electrons has been studied. Results indicate a clear difference between optical emissions under positron and electron bombardment. The positron-induced luminescence spectrum is believed to be generated by both collisional and annihilation processes.

  13. Hydrothermal synthesis, crystal structure and luminescence property ...

    Indian Academy of Sciences (India)

    Hydrothermal synthesis, crystal structure and luminescence property of a three dimensional Sm(III) coordination polymer with. 2,5-pyridinedicarboxylic acid. KRANTHI KUMAR GANGU, ANIMA S DADHICH and. SARATCHANDRA BABU MUKKAMALA. ∗. Department of Chemistry, GITAM University, Visakhapatnam 530 045, ...

  14. luminescence in coloured alkali halide crystals

    Indian Academy of Sciences (India)

    electron emission and luminescence associated with the plastic deformation of ionic crys- tals. Chandra [28,29] has reported the dependence of ML of coloured alkali halide crystals on different parameters. Several workers have reported that post-irradiation deformation causes deformation bleaching in coloured alkali ...

  15. Hydrothermal synthesis, crystal structure and luminescence property ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 12. Hydrothermal synthesis, crystal structure and luminescence property of a three dimensional Sm(III) coordination polymer with 2,5-pyridinedicarboxylic acid. Kranthi Kumar Gangu Anima S Dadhich Saratchandra Babu Mukkamala. Volume 127 Issue 12 ...

  16. Synthesis, spectroscopic, electrochemical and luminescence studies ...

    Indian Academy of Sciences (India)

    hydrazino-5-mercapto-1,2,4-triazole (LH2) as co-ligand were synthesised and characterized by elemental analysis, IR, UV/Vis, 1H NMR spectra and FAB-mass data. The electrochemical and luminescent properties of the complexes were also ...

  17. Combustion synthesis and preliminary luminescence studies of ...

    Indian Academy of Sciences (India)

    The polycrystalline sample of LiBaPO4 : Tb3+ (LBPT) was successfully synthesized by solution combustion synthesis and studied for its luminescence characteristics. The thermoluminescence (TL) glow curve of LBPT material consists of two peaks at 204.54 and 251.21°C. The optimum concentration was 0.005 mol to ...

  18. Synthesis, crystal structure, theoretical study and luminescence ...

    Indian Academy of Sciences (India)

    Synthesis, crystal structure, theoretical study and luminescence property of a butterfly-like W/Cu/S cluster with 1,10-phenanthroline. AI-HUA CHENa,b, SU-CI MENGc,d, JIN-FANG ZHANGb,c and CHI ZHANGb,c,∗. aSchool of Chemical & Chemical Engineering, Yancheng Institute of Technology, Yancheng 224051,.

  19. Combustion synthesis and preliminary luminescence studies of ...

    Indian Academy of Sciences (India)

    Abstract. The polycrystalline sample of LiBaPO4 : Tb3+ (LBPT) was successfully synthesized by solution com- bustion synthesis and studied for its luminescence characteristics. The thermoluminescence (TL) glow curve of. LBPT material consists of two peaks at 204.54 and 251.21◦C. The optimum concentration was 0.005 ...

  20. Multistate Luminescent Solar Concentrator "Smart" Windows

    NARCIS (Netherlands)

    Sol, Jeroen A.H.P.; Timmermans, Gilles H.; Breugel, van Abraham J.; Schenning, Albertus P.H.J.; Debije, Michael G.

    2018-01-01

    A supertwist liquid crystalline luminescent solar concentrator (LSC) "smart" window is fabricated which can be switched electrically between three states: one designed for increased light absorption and electrical generation (the "dark" state), one for transparency (the "light" state), and one for

  1. Probing luminescence centers in Na rich feldspar

    DEFF Research Database (Denmark)

    Prasad, Amit Kumar; Lapp, Torben; Kook, Myung Ho

    2016-01-01

    In contrast to the detailed investigations on the dosimetric electron trap in feldspar only little has been done to understand the luminescence centers. We use a comparison of multiple spectroscopic techniques, site selective photoluminescence spectroscopy and time resolved measurements to further...

  2. Effect of CH3OH on the luminescent properties of the [Zn(sfdb)(bpy)(H2O)]n · 0.5nCH3OH metal-organic framework

    Science.gov (United States)

    Song, Xuedan; Liu, Zhiqiao; Shi, Yantao; Hao, Juanyuan; Qiu, Jieshan; Hao, Ce

    2015-01-01

    The influence of CH3OH solvent on the luminescent properties of the [Zn(sfdb)(bpy)(H2O)]n · 0.5nCH3OH (sfdb = 4,4-sulfonyldibenzoic acid, bpy = 2,2-bipyridine) metal-organic framework (MOF) was investigated by considering the hydrogen bond between CH3OH and [Zn(sfdb)(bpy)(H2O)]n in an electronically excited state using density functional theory and time-dependent density functional theory methods. The calculated geometry, infrared spectrum, and UV-vis spectrum in the ground state are consistent with the experimental results. The frontier molecular orbitals and electronic configuration indicated that the origin of the luminescence is ligand-to-ligand charge transfer rather than ligand-to-metal charge transfer, as has been previously proposed. We found that the O3⋯H11 hydrogen bond is weaker in the excited state than in the ground state, and the weaker hydrogen bond in the electronically excited state should enhance the luminescence. The results show that the CH3OH solvent changes the luminescence properties of [Zn(sfdb)(bpy)(H2O)]n, which provides potential opportunities for the design of diverse luminescent MOFs.

  3. Proton induced luminescence of minerals

    Energy Technology Data Exchange (ETDEWEB)

    Calvo del Castillo, H.; Millan, A.; Calderon, T. [Depto. Geologia y Geoquimica, Universidad Autonoma de Madrid, Ctra. Colmenar, km. 15, 28049, Madrid (Spain); Beneitez, P. [Departamento Quimica Fisica Aplicada, Universidad Autonoma de Madrid Cantoblanco, Madrid (Spain); Ruvalcaba S, J.L. [lFUNAM, Circuito de la lnvestigacion Cientifica s/n, Ciudad Universitaria, 04510 Mexico D.F. (Mexico)

    2008-07-01

    This paper presents a summary of Ionoluminescence (IL) for several minerals commonly found in jewellery pieces and/or artefacts of historical interest. Samples including silicates and non-silicates (native elements, halide, oxide, carbonate and phosphate groups) have been excited with a 1.8 MeV proton beam, and IL spectra in the range of 200- 900 nm have been collected for each one using a fiber optic coupled spectrometer. Light emissions have been related to Cr{sup 3+}, Mn{sup 2+} and Pr{sup 3+} ions, as well as intrinsic defects in these minerals. Results show the potential of IL for impurity characterization with high detection limits, local symmetry studies, and the study of the origin of minerals. (Author)

  4. A low-cost smartphone-based platform for highly sensitive point-of-care testing with persistent luminescent phosphors.

    Science.gov (United States)

    Paterson, Andrew S; Raja, Balakrishnan; Mandadi, Vinay; Townsend, Blane; Lee, Miles; Buell, Alex; Vu, Binh; Brgoch, Jakoah; Willson, Richard C

    2017-03-14

    Through their computational power and connectivity, smartphones are poised to rapidly expand telemedicine and transform healthcare by enabling better personal health monitoring and rapid diagnostics. Recently, a variety of platforms have been developed to enable smartphone-based point-of-care testing using imaging-based readout with the smartphone camera as the detector. Fluorescent reporters have been shown to improve the sensitivity of assays over colorimetric labels, but fluorescence readout necessitates incorporating optical hardware into the detection system, adding to the cost and complexity of the device. Here we present a simple, low-cost smartphone-based detection platform for highly sensitive luminescence imaging readout of point-of-care tests run with persistent luminescent phosphors as reporters. The extremely bright and long-lived emission of persistent phosphors allows sensitive analyte detection with a smartphone by a facile time-gated imaging strategy. Phosphors are first briefly excited with the phone's camera flash, followed by switching off the flash, and subsequent imaging of phosphor luminescence with the camera. Using this approach, we demonstrate detection of human chorionic gonadotropin using a lateral flow assay and the smartphone platform with strontium aluminate nanoparticles as reporters, giving a detection limit of ≈45 pg mL -1 (1.2 pM) in buffer. Time-gated imaging on a smartphone can be readily adapted for sensitive and potentially quantitative testing using other point-of-care formats, and is workable with a variety of persistent luminescent materials.

  5. Three-photon-induced upconversion luminescence of lead bromide CH3NH3PbBr3 perovskites

    Science.gov (United States)

    Bagherzadeh-Khajehmarjan, Elnaz; Mirershadi, Soghra; Ahmadi-Kandjani, Sohrab

    2017-10-01

    In this paper, upconversion luminescence from CH3NH3PbBr3 perovskite under pulsed laser illumination is reported. Excitation of bromide perovskite powders with a UV wavelength results in green PL bands at 562 nm. Infrared-to-visible upconversion luminescence is demonstrated in CH3NH3PbBr3 hybrid perovskites under 1064 nm nanosecond pulsed laser irradiation at room temperature. The shapes of both emission spectra are nearly identical, with a maximum at 562 nm. The green fluorescence emission is discernible by the naked eye. A remarkable feature of CH3NH3PbBr3 perovskite is the fact that fluorescence emission can be induced UV or NIR wavelength through different absorption processes. Upconversion luminescence is identified by measuring the NIR pump beam intensity dependence of luminescence which illustrates that the upconverted emission is induced by three-photon absorption process. The quadratic dependency of PL peak position on incident intensity is also another verification for the three-photon absorption process.

  6. Aromatic compounds in molecular phase of Baltic amber-synchronous luminescence analysis.

    Science.gov (United States)

    Matuszewska, Aniela; Czaja, Maria

    2002-04-08

    Synchronous luminescence analysis was performed in order to identify aromatic compounds in solvent extracts of Baltic amber. The investigated extracts were obtained, for comparisons, as products of extraction by various techniques and solvents. Methylene chloride and ethanol were applied independently for extraction at the ambient temperature (conservative extraction), as well as at the temperature of solvent boiling (extraction in Soxhlet apparatus). Ethanol, as the solvent, was also used for extraction in an ultrasonic bath and for the decoction process. The extraction, by techniques mentioned, of the analysed amber has resulted in products generally containing the same groups of aromatics: mainly naphthalenes, phenanthrenes and anthracenes. Among phenanthrenes, in all samples the retene was also identified, being one of the characteristic links of the diagenetic chain of chemical transformations of vegetal precursors. The identification of a series of individual compounds made, using the synchronous luminescence technique, was verified by the record of conventional emission and excitation spectra. Presented identified compounds were also confirmed by the results of GC-MS analysis. The luminescence analysis was also performed comparatively for fossil resin from Galicia, Spain (Cretaceous) older than Baltic amber (Tertiary, Eocene). The obtained preliminary results of synchronous luminescence analysis suggest the possibility of diversification in this manner of fossil resins of various ages by characterisation of aromatisation degree and alkyl substitution of aromatic rings. It is since well known that aromatisation progress is an indicator of a natural process of maturation of fossil organic matter. However, a greater number of samples should be taken to further testify to the investigations.

  7. Reverse lyotropic liquid crystals from europium nitrate and P123 with enhanced luminescence efficiency.

    Science.gov (United States)

    Yi, Sijing; Li, Qintang; Liu, Hongguo; Chen, Xiao

    2014-10-02

    Fabrication of lyotropic aggregates containing the lanthanide ions is becoming a preferable way to prepare novel functional materials. Here, the lyotropic liquid crystals (LLCs) of reverse hexagonal, reverse bicontinuous cubic, and lamellar phases have been constructed in sequence directly from the mixtures of Eu(NO3)3·6H2O and Pluronic P123 amphiphilc block copolymer with increasing the salt proportion. Their phase types and structural characteristics were analyzed using polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements. The driving forces of reverse LLC phase formation were investigated using Fourier-transformed infrared spectroscopy (FTIR) and rheological measurements. The hydrated europium salt was found to act not only as a solvent here, but also as the bridge to form hydrogen bonding between coordinated water molecules and PEO blocks, which played a key role in the reverse LLCs formation. Compared to those in aqueous solutions and solid state, the enhanced luminescence quantum yields and prolonged excited state lifetimes were observed in two europium containing reverse mesophases. The luminescence quenching effect of lanthanide ions was efficiently suppressed, probably due to the substitution of coordinated water molecules by oxyethyl groups of P123 and ordered phase structures of LLCs, where the coordinated europium ions were confined and isolated by PEO blocks. The optimum luminescence performance was then found to exist in the reverse hexagonal phase. The obtained results on such lanthanide-induced reverse LLCs should be referable for designing new luminescent soft materials construction to expand their application fields.

  8. Fabrication and luminescent properties of Ce:LaAlO3 translucent ceramics

    Science.gov (United States)

    Lu, Qing; Yang, Qiuhong; Wang, Yonggang; Duan, Qizhen; Yuan, Ye; Cen, Jiang

    2015-04-01

    Ce3+ doped LaAlO3 translucent ceramics were fabricated with solid-state reaction method and sintered in vacuum condition. LaAlO3 single phase was formed at 1200 °C. Their microstructures were observed and luminescent properties were investigated. The average grain size increases with the increase of sintering temperature. A dense and pore-free microstructure is displayed at 1700 °C. A band to band absorption of LaAlO3 host is round 220 nm. Three excitation peaks at 249, 317 and 354 nm were observed in the Ce3+:LaAlO3 ceramics, they were attributed to the 4f-5d transition of Ce3+ ions. The scintillation properties were investigated by X-ray excited radioluminescence in Ce3+:LaAlO3 ceramics and the emission peak is 428 nm.

  9. Electron beam excitation assisted optical microscope with ultra-high resolution.

    Science.gov (United States)

    Inami, Wataru; Nakajima, Kentaro; Miyakawa, Atsuo; Kawata, Yoshimasa

    2010-06-07

    We propose electron beam excitation assisted optical microscope, and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.

  10. Excitations in organic solids

    CERN Document Server

    Agranovich, Vladimir M

    2009-01-01

    During the last decade our expertise in nanotechnology has advanced considerably. The possibility of incorporating in the same nanostructure different organic and inorganic materials has opened up a promising field of research, and has greatly increased the interest in the study of properties of excitations in organic materials. In this book not only the fundamentals of Frenkel exciton and polariton theory are described, but also the electronic excitations and electronic energytransfers in quantum wells, quantum wires and quantum dots, at surfaces, at interfaces, in thin films, in multilayers,

  11. Luminescent microporous metal-organic framework with functional lewis basic sites on the pore surface: specific sensing and removal of metal ions.

    Science.gov (United States)

    Jayaramulu, Kolleboyina; Narayanan, Raghu Pradeep; George, Subi J; Maji, Tapas Kumar

    2012-10-01

    A three-dimensional luminescent metal-organic framework, {Mg(DHT)(DMF)(2)}(n) (1), based on an excited-state intramolecular proton-transfer (ESIPT) responsive linker, 2,5-dihydroxyterephthalic acid (H(2)DHT), has been synthesized, and its desolvated microporous framework with pendent -OH groups on the pore surface was exploited for the binding and specific sensing of metal ions via Lewis acid-base interactions. The luminescence intensity significantly quenches with Cu(II) among various s- and d-block metal ions, and highly selective sensing of Cu(II) ions has been realized in both solid and solution states (up to nanomolar concentration). The immobilized Cu(II) metal ions can be selectively removed by chelating agents like ethylenediaminetetraacetic acid without any structural disintegration of the framework, as revealed by the luminescence and gas-adsorption studies.

  12. Excitation Methods for Bridge Structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  13. Luminescent polymethacrylate composite nanofibers containing a benzoic acid rare earth complex: Morphology and luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Fulai [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); Xi, Peng, E-mail: xpsyq0007@sina.com [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); State Key laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing (China); Xia, Haiying; Wang, Chaohua; Gao, Li [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); Cheng, Bowen, E-mail: Bowen@tjpu.edu.cn [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China)

    2015-08-25

    Highlights: • We synthesize PMMA composite nanofibers containing benzoic acid rare earth complex. • We investigate the effects of nanofiber morphology on luminescence properties. • Nanofibers with different morphologies had different luminescence characteristics. • Fluorescence intensity and emission lifetime of porous nanobeads were the highest. • Nanofibers with a porous structure showed the stronger fluorescent recognition ability. - Abstract: In this study, we systematically investigated the morphologies and luminescence properties of luminescent polymethacrylate composite nanofibers containing a benzoic acid rare earth complex. The analysis results indicated that the benzoic acid rare earth complex, Tb(4-methylbenzoic acid){sub 3}phen, was distributed uniformly in the polymethacrylate nanofibers, which were fabricated by electrostatic spinning. The Tb(4-methylbenzoic acid){sub 3}phen content in the polymethacrylate nanofibers was as high as 20% (mass%). The emission peaks of the as-prepared polymethacrylate composite nanofibers corresponded to the characteristic {sup 5}D{sub 4}–{sup 7}F{sub 6,5,4,3} transitions of Tb{sup 3+} ions. The highest emission peak was observed at 548 nm and corresponded to the {sup 5}D{sub 4}–{sup 7}F{sub 5} transition. When the Tb(4-methylbenzoic acid){sub 3}phen content was less than 1%, even a 0.2% increase in the content increased the fluorescence intensity markedly. The thermal stability of the rare earth complex was higher in the as-prepared nanofibers; the initial decomposition temperature of the polymethacrylate composite nanofiber reached 291 °C. Composite nanofibers with different morphologies exhibited different luminescence characteristics. The fluorescence intensity and emission lifetime of porous nanobeads were nine and two times higher, respectively, than those of smooth nanofibers. The better morphological and luminescence properties exhibited by the synthesized luminescent polymethacrylate composite

  14. Photostimulable near-infrared persistent luminescent nanoprobes for ultrasensitive and longitudinal deep-tissue bio-imaging.

    Science.gov (United States)

    Chuang, Yen-Jun; Zhen, Zipeng; Zhang, Fan; Liu, Feng; Mishra, Jyoti P; Tang, Wei; Chen, Hongmin; Huang, Xinglu; Wang, Lianchun; Chen, Xiaoyuan; Xie, Jin; Pan, Zhengwei

    2014-01-01

    In vivo fluorescence imaging suffers from suboptimal signal-to-noise ratio and shallow detection depth, which is caused by the strong tissue autofluorescence under constant external excitation and the scattering and absorption of short-wavelength light in tissues. Here we address these limitations by using a novel type of optical nanoprobes, photostimulable LiGa5O8:Cr(3+) near-infrared (NIR) persistent luminescence nanoparticles, which, with very-long-lasting NIR persistent luminescence and unique photo-stimulated persistent luminescence (PSPL) capability, allow optical imaging to be performed in an excitation-free and hence, autofluorescence-free manner. LiGa5O8:Cr(3+) nanoparticles pre-charged by ultraviolet light can be repeatedly (>20 times) stimulated in vivo, even in deep tissues, by short-illumination (~15 seconds) with a white light-emitting-diode flashlight, giving rise to multiple NIR PSPL that expands the tracking window from several hours to more than 10 days. Our studies reveal promising potential of these nanoprobes in cell tracking and tumor targeting, exhibiting exceptional sensitivity and penetration that far exceed those afforded by conventional fluorescence imaging.

  15. Characterization and Luminescence Properties of Color-Tunable Dy3+-Doped BaY2ZnO5 Nanophosphors

    Science.gov (United States)

    Sonika; Khatkar, S. P.; Khatkar, Avni; Kumar, Rajesh; Taxak, V. B.

    2015-01-01

    Dy3+-doped BaY2ZnO5 nanophosphors were successfully synthesized by use of a solution combustion process. The effects of sintering temperature and dysprosium concentration on the structural and luminescence characteristics of the phosphors were investigated. X-ray diffraction (XRD) analysis confirmed the formation of pure orthorhombic BaY2ZnO5 with the space group Pbnm at 1100°C. Morphological investigation revealed spherical nanoparticles with smooth surfaces. The luminescence features of the nanophosphor were studied by use of photoluminescence excitation (PLE) and photoluminescence emission (PL), with luminescence decay curves and color ( x, y) coordinates. On excitation at 355 nm, BaY2ZnO5 nanophosphor doped with trivalent dysprosium ion emits white light as a mixture of blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emission. Concentration quenching is explained on the basis of cross-relaxation between intermediate Dy3+ states. Thus, BaY2ZnO5:Dy3+ nanophosphor may be suitable for producing efficient white light for ultraviolet-light-emitting diodes (UV-LEDs), fluorescent lamps, and a variety of optical display panels.

  16. Synthesis and Luminescence Properties of Eu3+ Doped High Temperature Form of Bi2MoO6

    Science.gov (United States)

    Han, Bing; Zhang, Jie; Li, Pengju; Li, Jianliang; Bian, Yang; Shi, Hengzhen

    2015-03-01

    This work reports on the luminescence properties of the Eu3+-doped high-temperature form of Bi2MoO6 by a solid-state reaction technique at high temperature. Various characterization methods including x-ray diffraction, scanning electron microscopic, Fourier transform infrared, and fluorescence spectroscopy measurements were utilized in order to investigate the phase purity and surface morphology as well as photoluminescence properties for as-prepared phosphors. The spectroscopic characteristics including excitation and emission spectrum, concentration quenching phenomenon, decay curves, and chromaticity coordinates are discussed in detail. The nature of the luminescence behavior of Eu3+ was understood in term of the Judd-Ofelt theory, and the luminescent quantum efficiency of 5D0 → 7F2 transition of Eu3+ was estimated. The as-prepared phosphors can be effectively excited with a 465-nm blue light, and exhibit a reddish-orange emission belonging to the prevailing 5D0 → 7F2 transition of Eu3+ with a decay time of milliseconds. This indicates that the Bi2MoO6:Eu3+ phosphors could have potential application in white light-emitting diodes (w-LEDs) based on blue LED chips.

  17. Non-blinking and photostable upconverted luminescence from single lanthanide-doped nanocrystals

    Science.gov (United States)

    Wu, Shiwei; Han, Gang; Milliron, Delia J.; Aloni, Shaul; Altoe, Virginia; Talapin, Dmitri V.; Cohen, Bruce E.; Schuck, P. James

    2009-01-01

    The development of probes for single-molecule imaging has dramatically facilitated the study of individual molecules in cells and other complex environments. Single-molecule probes ideally exhibit good brightness, uninterrupted emission, resistance to photobleaching, and minimal spectral overlap with cellular autofluorescence. However, most single-molecule probes are imperfect in several of these aspects, and none have been shown to possess all of these characteristics. Here we show that individual lanthanide-doped upconverting nanoparticles (UCNPs)—specifically, hexagonal phase NaYF4 (β-NaYF4) nanocrystals with multiple Yb3+ and Er3+ dopants—emit bright anti-Stokes visible upconverted luminescence with exceptional photostability when excited by a 980-nm continuous wave laser. Individual UCNPs exhibit no on/off emission behavior, or “blinking,” down to the millisecond timescale, and no loss of intensity following an hour of continuous excitation. Amphiphilic polymer coatings permit the transfer of hydrophobic UCNPs into water, resulting in individual water-soluble nanoparticles with undiminished photophysical characteristics. These UCNPs are endocytosed by cells and show strong upconverted luminescence, with no measurable anti-Stokes background autofluorescence, suggesting that UCNPs are ideally suited for single-molecule imaging experiments. PMID:19541601

  18. Chromophore-immobilized luminescent metal-organic frameworks as potential lighting phosphors and chemical sensors.

    Science.gov (United States)

    Wang, Fangming; Liu, Wei; Teat, Simon J; Xu, Feng; Wang, Hao; Wang, Xinlong; An, Litao; Li, Jing

    2016-08-11

    An organic chromophore H4tcbpe-F was synthesized and immobilized into metal-organic frameworks along with two bipyridine derivatives as co-ligands to generate two strongly luminescent materials [Zn2(tcbpe-F)(4,4'-bpy)·xDMA] (1) and [Zn2(tcbpe-F)(bpee)·xDMA] (2) [4,4'-bpy = 4,4'-bipyridine, bpee = 4,4'-bipyridyl-ethylene, tcbpe-F = 4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl)tetrakis(3-fluoro-[1,1'-biphenyl]-4-carboxylic acid), DMA = N,N-dimethylacetamide]. Compounds 1 and 2 are isoreticular and feature a 2-fold interpenetrated three-dimensional porous structure. Both compounds give green-yellow emission under blue light excitation. Compound 1 has a high internal quantum yield of ∼51% when excited at 455 nm and shows selective luminescence signal change (e.g. emission energy and/or intensity) towards different solvents, including both aromatic and nonaromatic volatile organic species. These properties make it potentially useful as a lighting phosphor and a chemical sensor.

  19. Microscale luminescence imaging of defects, inhomogeneities, and secondary phases in halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Lam, S., E-mail: lam@capesym.com; Swider, S.; Fiala, J.; Datta, A.; Motakef, S.

    2015-06-01

    A microscale luminescence system was custom-built to investigate crystallinity, crystal quality, and emission homogeneity in scintillator crystals. This system consists of a fluorescence microscope that has been integrated with a spectrometer and custom-software for both manual and automated collection of two-dimensional reflection and emission images and maps of scintillators under excitation. The system’s capabilities are demonstrated through imaging studies on samples of CsBa{sub 2}I{sub 5} (2%Eu) (CBI), CsI (5%Ba, 3%Eu), and SrI{sub 2} (5%Eu). Emission images obtained under 365 nm excitation reveal features that cannot be visualized using light microscopy alone. In the CBI samples, rod-like structures of 100–200 μm in diameter were observed. Using electron probe microanalysis (EPMA), these rods were found to be rich in barium and poor in cesium and europium. In CsI (Ba, Eu), oblong features were observed. Electron probe microanalysis confirmed that these regions varied in composition. Finally, an emission map of a one-inch diameter disk of SrI{sub 2} (Eu) indicated a uniform distribution of the dopant. This study demonstrates that the microscale luminescence system is a valuable complement to the current suite of scintillator characterization tools. Its capabilities for evaluating crystal quality and homogeneity will provide useful feedback for crystal growth optimization.

  20. Ce3+-sensitized red Mn2+ luminescence in calcium aluminoborate phosphor material

    Science.gov (United States)

    Puchalska, M.; Zych, E.

    2017-12-01

    Ce3+ doped and Ce3+,Mn2+ co-doped calcium aluminoborate (CAB) phosphors were synthesised by solid-state reaction method and their optical properties were studied. X-ray powder diffraction, SEM and TEM studies indicated the crystallization of the main trigonal CaAl2B2O7 phase and the presence of an additional non-crystalline phase. It was also observed that increasing dopant concentration promotes phase separation. Hence, both series of phosphors demonstrated the changes in luminescence properties via activator concentration variation. Upon UV excitation (λex = 310 nm) Ce3+ doped and Ce3+,Mn2+ co-doped materials yielded intensive blue and pinkish luminescence, respectively. The spectra of CAB:Ce3+ samples showed a broad emission band due to 5d→4f transition of Ce3+, which broadened and shifted to longer wavelengths with increasing dopant content. Mn2+ co-doping caused appearance of another broad-band emission with a maximum of 680 nm, resulting from the 4T1(4G) →6A1(6S) transition of Mn2+. Detailed analysis of the emission and excitation spectra as well as decay time traces as a function of dopant concentration showed that efficient resonant energy transfer mainly occurs between Ce3+ and Mn2+ incorporated in the non-crystalline phase in CAB material. The estimated values of energy transfer efficiency of CAB:Ce3+(3%),Mn2+(4%) is close to 52%.

  1. Thermal annealing effects on ultra-violet luminescence properties of Gd doped AlN

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Takashi; Ishizu, Yuta; Tsuji, Kazuma; Harada, Yukihiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan); Chigi, Yoshitaka; Nishimoto, Tetsuro; Tanaka, Hiroyuki; Kobayashi, Mikihiro [YUMEX INC., 400 Itoda, Yumesaki, Himeji, Hyogo 671-2114 (Japan); Ishihara, Tsuguo; Izumi, Hirokazu [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira, Suma, Kobe 654-0037 (Japan)

    2015-04-28

    We studied energy transfer from AlN to doped Gd{sup 3+} ions as a function of the post-thermal annealing temperature. Gd-doped AlN thin films were deposited on fused-silica substrates using a reactive radio-frequency magnetron sputtering technique. The film is a c-axis oriented polycrystal. The intra-orbital electron transition in Gd{sup 3+} showed an atomically sharp luminescence at 3.9 eV (318 nm). The photoluminescence (PL) excitation spectrum exhibited a resonant peak, indicating efficient energy transfer from the host AlN crystal to Gd{sup 3+} ions. The PL intensity increases approximately ten times by thermal annealing. The PL decay lifetime becomes long with annealing, and mid-gap luminescence relating to the crystal defects in AlN was also found to be reduced by annealing. These results suggest that energy dissipation of excited carriers in AlN was suppressed by annealing, and the efficiency of energy transfer into Gd{sup 3+} was improved.

  2. Two-photon absorption and upconversion luminescence of colloidal CsPbX3 quantum dots

    Science.gov (United States)

    Han, Qiuju; Wu, Wenzhi; Liu, Weilong; Yang, Qingxin; Yang, Yanqiang

    2018-01-01

    The nonlinear optical and the upconversion luminescence (UCL) properties of CsPbX3 (X = Br or its binary mixtures with Cl, I) quantum dots (QDs) are investigated by femtosecond open-aperture (OA) Z-scan and time-resolved luminescence techniques in nonresonant spectral region. The OA Z-scan results show that CsPbX3 QDs have strong reverse saturable absorption (RSA), which is ascribed to two-photon absorption. Partially changing halide composition from Cl to Br, to I, two-photon absorption cross sections become larger at the same laser excitation intensity. The composition-tunable nonlinear absorption should be attributed to the gradual decrease of the lowest direct band gaps with the halide substitute. Moreover, the strong UCL can be observed under near infrared femtosecond laser excitation. Halide composition-tunable UCL dynamics of CsPbX3 QDs is analyzed by use of two-exponential fitting with deconvolution. When CsPbX3 QDs have similar sizes (10-13 nm), with partially changing halide composition from Cl to Br, to I, the average UCL lifetime becomes longer due to the variation of Kane energy. Our findings suggest all-inorganic perovskite QDs can be used as excellent gain medium for high-performance frequency-upconversion lasers and provide reference to engineer such QDs toward practical optoelectronic applications.

  3. Photo-luminescent quantum dots used for security identification

    Science.gov (United States)

    Chang, Shoude; Yu, Kui; Liu, Jiaren

    2007-10-01

    Information retrieval is critical in security technologies such as those for status identification and documentation authentication. Ideally, coding materials should be difficult to locate, impossible to counterfeit, and easy to process. This presentation addresses a novel information retrieval technology with these ideal features of its coding materials: the photo-luminescent (PL) quantum-dots (QD) synthesized via wet-chemistry approaches. As compared to traditional PL materials, they exhibit emission with narrower full width at half maximum, greater brightness, and higher photo-stability; also, their PL wavelength can be easily and accurately tuned via their size, structure, and composition. Due to such a feasible tune-ability, mainly, QDs have demonstrated enormous potential applications in security and defense. When QDs are excited, they can provide coded information with their PL wavelength and intensity. If the coding wavelengths from the QD PL are designed as the Fraunhofer lines, i.e. black lines in solar spectrum, the retrieval system can extract the useful information even under sunshine covering areas. Multi-photon excitation (MPE) technologies can further extend applications of QDs to multi-layer information extraction. For an info-label of 2-millimeter in depth, a MPE system with the depth resolution less than one micro-meter can thus achieve 2 GB resolutions, when a coding material exhibiting 6 PL wavelengths with 10 intensity levels. In general, transparent thin-film coating of QDs can be applied to various substrates, such as documents, fingernails, and military helmets and vehicles. Moreover, QD based security information can be easily destroyed by preset expiration in the presence of timing agents.

  4. Positron excitation of neon

    Science.gov (United States)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  5. Hardness and excitation energy

    Indian Academy of Sciences (India)

    It is shown that the first excitation energy can be given by the Kohn-Sham hardness (i.e. the energy difference of the ground-state lowest unoccupied and highest occupied levels) plus an extra term coming from the partial derivative of the ensemble exchange-correlation energy with respect to the weighting factor in the ...

  6. Excitation of Stellar Pulsations

    DEFF Research Database (Denmark)

    Houdek, G.

    2012-01-01

    In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

  7. Characterization of a nondestructive beam profile monitor using luminescent emission

    CERN Document Server

    Variola, A; Ferioli, G

    2007-01-01

    The LHC (large hadron collider) [LHC study group: LHC. The large hadron collider conceptual design; CERN/AC/95-05] is the future p-p collider under construction at CERN, Geneva. Over a circumference of 26.7 km a set of cryogenic dipoles and rf cavities will store and accelerate proton and ion beams up to energies of the order of 7 TeV. Injection in LHC will be performed by the CERN complex of accelerators, starting from the source and passing through the linac, the four booster rings, the proton synchrotron (PS), and super proton synchrotron (SPS) accelerators. One of the main constraints on LHC performance is emittance preservation along the whole chain of CERN accelerators. The accepted relative normalized emittance blowup after filamentation is ±7%. To monitor the beam and the emittance blowup process, a study of different prototypes of nonintercepting beam profile monitors has been performed. In this context a monitor using the luminescent emission of gases excited by ultrarelativistic protons (450 GeV) ...

  8. Luminescence properties of Er3+-doped phosphate glasses

    Science.gov (United States)

    Hraiech, S.; Bouzidi, C.; Férid, M.

    2017-10-01

    Erbium doped phosphate glasses with composition P2O5 - Na2O - B2O3 -x Er2O3 were obtained using melt-quench method. The spectroscopic properties were analyzed using optical absorption and fluorescence spectra. Based on the absorption spectra and Judd-Ofelt theory, the Judd-Ofelt intensity parameters, Ω2, Ω4, and Ω6 were determined and then used to calculate the total spontaneous transition probability (Atot), radiative life time (τr) and the branching ratio (β), for various excited luminescent states. The spectroscopic quality factor Ω4/Ω6 has been calculated for the present Er3+ doped phosphate glasses (1.53, 1.69 and 1.02) and is found to be in the same order than the reported Er3+ glasses, that makes our glasses are suitable for various photonic applications. Optical band gap energy (Eopt) values through direct and indirect allowed transitions of the prepared Er3+ glasses have also been determined and compared with similar studies.

  9. Influence of Ag nanoparticles on the luminescence dynamics of Dy3+ ions in glass: the "plasmonic diluent" effect.

    Science.gov (United States)

    Jiménez, José A

    2013-10-28

    This work demonstrates that metallic nanoparticles (NPs) embedded in rare-earth (RE) co-doped dielectrics are able to produce an effect analogous to a reduction in the effective concentration of the luminescent RE ions in the matrix, herein coined the "plasmonic diluent" effect. This has been revealed explicitly for Dy(3+) and Ag NP co-doped aluminophosphate glasses, which were investigated using optical absorption and photoluminescence (PL) spectroscopy with emphasis on the influence of plasmonic NPs on the luminescence decay dynamics of Dy(3+) ions. The glasses were prepared using the melt-quenching technique, where the precipitation of Ag NPs was subsequently induced by heat treatment (HT). The development of the surface plasmon resonance (SPR) band of Ag NPs at around 410 nm resulted in the quenching of Dy(3+) emission for the (4)F9/2 → (6)H15/2, (6)H13/2 transitions (484, 574 nm) under resonant excitation of (6)H15/2 → (4)I15/2 transition at 450 nm. The decay of the (4)F9/2 excited state was monitored at 574 nm (away from SPR) under excitation at 450 nm (within SPR), where the PL dynamics indicated the presence of two populations of Dy(3+) ions in the glasses, in connection with slow (τs) and fast (τf) lifetime components. A tendency of the decay times to increase gradually with HT holding time was observed as the volume fraction of the plasmonic Ag particles increased. The data are interpreted in terms of an ion-to-particle excitation energy transfer operating via surface plasmons in the nanoscale metal. This produces a Dy(3+) deactivation effect analogous to a lowering in the effective concentration of emitting Dy(3+) ions in the matrix, i.e., the metal NPs play a role as a "plasmonic diluent" in the glass system with respect to the luminescent RE ions.

  10. Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

    Science.gov (United States)

    Liu, Pei; Cheng, Wenjing; Yao, Yunhua; Xu, Cheng; Zheng, Ye; Deng, Lianzhong; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

    2017-11-01

    Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

  11. Rechargeable and LED-activated ZnGa2O4 : Cr3+near-infrared persistent luminescence nanoprobes for background-free biodetection.

    Science.gov (United States)

    Zhou, Zhihao; Zheng, Wei; Kong, Jintao; Liu, Yan; Huang, Ping; Zhou, Shanyong; Chen, Zhuo; Shi, Jianlin; Chen, Xueyuan

    2017-05-25

    Persistent luminescence nanoparticles (PLNPs) have shown great promise in the field of biomedicine, but are currently limited by the challenge in the synthesis of high-quality PLNPs with bright persistent luminescence and a long afterglow time. Herein, we report a facile strategy for the synthesis of monodisperse, rechargeable and LED-activated ZnGa 2 O 4  : Cr 3+ near-infrared (NIR) PLNPs based on a modified solvothermal liquid-solid-solution method. The as-synthesized PLNPs are not only flexible for bioconjugation, but could also circumvent the limitation of the weak persistent luminescence and short afterglow time that most PLNPs confronted owing to their rechargeable capability. It was unraveled that both thermal activation and quantum tunneling mechanisms contributed to the afterglow decay of the PLNPs, and the quantum tunneling was found to dictate the LED-activated afterglow intensity and lasting time. Furthermore, by utilizing the superior excitation-free persistent luminescence, we demonstrated for the first time the application of biotinylated ZnGa 2 O 4  : Cr 3+ PLNPs as background-free luminescent nano-bioprobes for sensitive and specific detection of avidin in a heterogeneous assay with a limit of detection down to ∼150 pM, thus revealing the great potential of these NIR PLNPs in ultrasensitive biodetection and bioimaging.

  12. Synthesis, characterization and luminescent properties of europium complexes with 2,4,6-tris-(2-pyridyl)-s-triazine as highly efficient sensitizers.

    Science.gov (United States)

    Kang, Jie; Chen, Ying-Nan; Wang, Ai-Ling; Li, Hai-Yan; Qu, Yan-Rong; Zhang, Hai-Xia; Chu, Hai-Bin; Zhao, Yong-Liang

    2015-12-01

    Using 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) as a neutral ligand, and p-hydroxybenzoic acid, terephthalic acid and nitrate as anion ligands, five novel europium complexes have been synthesized. These complexes were characterized using elemental analysis, rare earth coordination titrations, UV/vis absorption spectroscopy and infrared spectroscopy. Luminescence spectra, luminescence lifetime and quantum efficiency were investigated and the mechanism discussed in depth. The results show that the complexes have excellent emission intensities, long emission lifetimes and high quantum efficiencies. The superior luminescent properties of the complexes may be because the triplet energy level of the ligands matches well with the lowest excitation state energy level of Eu(3+). Moreover, changing the ratio of the ligands and metal ions leads to different luminescent properties. Among the complexes, Eu2(TPTZ)2(C8H4O4)(NO3)4(C2H5OH)·H2O shows the strongest luminescence intensity, longest emission lifetime and highest quantum efficiency. Copyright © 2015 John Wiley & Sons, Ltd.

  13. Application of the Metal-Organic Framework [Eu(BTC)] as a Luminescent Marker for Gunshot Residues: A Synthesis, Characterization, and Toxicity Study.

    Science.gov (United States)

    Lucena, Marcella A M; Oliveira, Marina F L; Arouca, Aline M; Talhavini, Márcio; Ferreira, Eduardo A; Alves, Severino; Veiga-Souza, Fabiane H; Weber, Ingrid T

    2017-02-08

    The 3D metal-organic framework (MOF) [Eu(BTC)] (where BTC = trimesic acid) was synthesized in 20 min by a microwave-assisted hydrothermal method with a yield of 89%. A structural and spectroscopic study, performed by X-ray diffraction, thermogravimetry, and photoluminescence spectroscopy, showed that this framework has high crystallinity, thermal stability, and luminescence. This MOF had a red-orange luminescence when excited with ultraviolet (UV) radiation (λ = 254 nm) and a high potential for use as a luminescent marker for gunshot residues (GSR). When added to 9 mm nontoxic ammunition, it greatly improved quality of the crime scene investigation, allowing for direct visualization of the luminescent GSR on the shooter's hand and firearm and at the firing range using only a portable UV lamp. The marked luminescent GSR was easily collected and characterized by nondestructive techniques, including with a Video Spectral Comparator and scanning electron microscopy/energy-dispersive spectroscopy, wherein the presence of Eu 3+ ions was confirmed. Furthermore, the oral acute toxicity of this MOF was assessed in adult female Wistar rats using the Organisation for Economic Cooperation and Development 423 guidelines. This study classified the MOF [Eu(BTC)] in a less toxic Globally Harmonized System category (category 5), with a LD 50 (lethal dose) of 5000 mg/kg, ensuring a wide security range for its application.

  14. GeS2-In2S3-CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence.

    Science.gov (United States)

    Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

    2016-11-21

    Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm(3+), Er(3+), and Dy(3+)) doped 65GeS2-25In2S3-10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm(3+), Er(3+), and Dy(3+) ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions.

  15. Luminescent lanthanide chelates and methods of use

    Science.gov (United States)

    Selvin, Paul R.; Hearst, John

    1997-01-01

    The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

  16. Photo-Luminescent Targets in Space

    Science.gov (United States)

    Maida, James; Kolomenski, Andrei

    2017-01-01

    Photo-luminescent ("glow in the dark") products have seen a dramatic increase in performance is the last 15 years with the use of a strontium aluminate formulation. Because of this, ISS uses photo-luminescent markers for interior emergency egress guidance. The marker is COTS material composed of strontium aluminate doped with europium, imbedded in PVC and achieves a light emission performance rated at 600/90 (600 mcd at 10 minutes and 90 mcd at 1 hour, 2 mcd is minimum required for human visibility). The ICA goal is to determine this material's effectiveness for use externally on ISS and/or on visiting vehicles, when packaged in Lexan for UV protection. A thermal test was conducted by EC to characterize the luminance emission profile of the material at extreme cold and hot temperatures, such as experienced on ISS.

  17. Optically stimulated luminescence dating of rock surfaces

    DEFF Research Database (Denmark)

    Sohbati, Reza

    There are many examples of rock surfaces, rock art and stone structures whose ages are of great importance to the understanding of various phenomena in geology, climatology and archaeology. Optically stimulated luminescence (OSL) dating is a well-established chronological tool that has successfully...... determined the depositional age of a wide variety of fine-grained sediments, from several years to several hundred thousands of years. However, there is no routine OSL dating method applicable to larger clasts such as cobbles, boulders and other rock surfaces. Here the application of quartz OSL to the dating...... of rock surfaces is successfully tested by application to two different quartz-rich rock types (sandstone and quartzite). Together with the measurement of infrared stimulated luminescence (IRSL) signals as a function of depth into the surface of different granites it is clear that both OSL and IRSL can...

  18. New luminescence measurement facilities in retrospective dosimetry

    DEFF Research Database (Denmark)

    Lapp, Torben; Jain, Mayank; Thomsen, Kristina Jørkov

    2012-01-01

    thermoelectrically cooled NIR sensitive PMT (detection window peak at 855 nm, FWHM 27 nm). Software and electronics have been modified to allow standard TL and OSL measurements in the same sequence as RL measurements. Together with a new bleaching source based on a high-power UV LED (395 nm; 700 mW/cm2......), this facility has been used to measure natural doses in feldspar using the decaying NIR RL signal.Secondly, we present a method for mapping radiation field of the built-in 90Sr/90Y β-source and estimating grain-location specific dose-rates. This is important for the accuracy of single grain results, when......This paper gives a review of recent developments in luminescence measurement facilities on the Risø TL/OSL reader including radio-luminescence (RL), exo-electron and violet stimulation attachments, and a method for characterising and if necessary correcting for beta irradiation source non...

  19. Luminescence from Tube-Arrest Bubbles in Pure Glycerin

    Science.gov (United States)

    Chen, Qi-Dai; Wang, Long

    2004-09-01

    Single transient cavitation bubble with luminescence has been generated in pure glycerin by using the `tube arrest' method. The analyses of high-speed photograph and light emission data suggest that the light emission would be a single bubble sonoluminescence. The luminescence pulse width is observed to vary from sub-nanosecond to about 30 ns. The width and intensity of luminescence pulses increases with the height of the liquid column height and decreases with the liquid temperature.

  20. Submicron Y2O3 particles codoped with Eu and Tb ions: size controlled synthesis and tuning the luminescence emission.

    Science.gov (United States)

    Atabaev, Timur Sh; Kim, Hyung-Kook; Hwang, Yoon-Hwae

    2012-05-01

    Eu(3+) and Tb(3+) codoped Y(2)O(3) submicron particles were prepared using the simple urea homogeneous precipitation method. X-ray diffraction patterns revealed the synthesized particles to have a pure cubic Y(2)O(3) structure. Field-emission scanning electron microscopy and field-emission transmission electron microscopy showed that the synthesized particles had almost uniform spherical shapes. The luminescence color emission of the synthesized particles could be tuned from red due to the effective (5)D(0)→(7)F(j) (j=0, 1, 2 and 3) transitions within Eu(3+) to green due to the (5)D(4)→(7)F(5) transition within Tb(3+) by switching the excitation wavelength from 255 to 310 nm. Luminescence quenching was observed at high dopant concentrations. Strong and effective color-tunable emission is expected to find a wide range of applications in industry. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Tunable and white light emitting AlPO4 mesoporous glass by design of inorganic/organic luminescent species

    Directory of Open Access Journals (Sweden)

    Jin He

    2015-04-01

    Full Text Available The realization of tunable and white light emitting sources employed by UV-LED with single-host phosphors has been an exciting development in the search for high luminous efficiency and excellent color rendering index white-light source. A tunable and white light emitting mesoporous glass was prepared by utilizing both inorganic/organic (Europium/coumarin luminescent species in the meso-structure. The tunable and white light emission was deliberately designed by CIE calculation based on the individual emission spectra, which was realized by tailoring the emission of Eu2+/Eu3+ ions and coumarin 535 in sol-gel AlPO4 mesoporous glass. This simple and versatile procedure is not limited in the combination of rare earth and organic dye and is therefore extendable to other luminescent species in meso-structure for color-tunable efficient solid-state lighting sources.

  2. Localization induced intense red upconversion luminescence in monodispersed K3ZrF7:Yb3+/Er3+ nanocrystals

    Science.gov (United States)

    Luo, Wenqin; Wu, Haiyan; Li, Bin

    2016-08-01

    There are increasing demands for upconversion (UC) nanocrystals since they are found to have important applications in the field of bio-imaging. Herein, novel monodispersed Yb3+/Er3+ co-doped K3ZrF7 nanocrystals with tunable sizes of 6-30 nm were prepared by high temperature co-precipitation method. Intense UC emission of Er3+ with large red to green ratio was obtained under the excitation of 980 nm-laser due to the cation localization effects. The UC luminescent lifetimes of 4S3/2 and 4F9/2 were determined to be 0.137 and 0.217 ms, respectively. At last, the possible upconversion mechanism was proposed basing on the pump power dependent UC luminescence experiments.

  3. [Luminescent cytochemical methods of detecting microorganisms].

    Science.gov (United States)

    Ivanovskaia, N P; Osin, N S; Khramov, E N; Zlobin, V N

    1999-01-01

    The paper shows that the luminescence cytochemical technique can be used for identification of microorganisms and microbiological synthesis products. The method is based on the interaction of specific fluorescence probes (ANS, terbium ions, and beta-diketonate complexes of europium, as well as metal-containing porphyrines) with major microbial intracellular components and toxins. Unlike classical microbiological, immunochemical or biochemical methods of detection, the proposed method has a reasonable versatility, specificity, sensitivity, rapid action, and possible automation.

  4. Broadband luminescence in liquid-solid transition

    CERN Document Server

    Achilov, M F; Trunilina, O V

    2002-01-01

    Broadband luminescence (BBL) intensity behavior in liquid-solid transition in polyethyleneglycol-600 has been established. Oscillation of BBL intensity observed in liquid-polycrystal transition are not found to observed in liquid-amorphous solid transition. It is shown that application of the theory of electron state tails to interpretation of BBL spectral properties in liquids demands restriction. BBL spectroscopy may be applied for optimization of preparation of polymers with determined properties. (author)

  5. Enhanced luminescence via energy transfer from Ag+ to RE ions (Dy3+, Sm3+, Tb3+) in glasses.

    Science.gov (United States)

    Li, JingJing; Wei, RongFei; Liu, XueYun; Guo, Hai

    2012-04-23

    Oxyfluoride glasses containing Ag species and rare earth (RE) ions (Dy(3+), Sm(3+), Tb(3+)) were prepared by melt-quenching technique. The type of luminescent species of novel excitation band (230-300 nm peaked at 255 nm) and emission band (300-600 nm peaked at 350 nm) were investigated by absorption, excitation, emission spectra, as well as decay lifetime measurements and can be ascribed to isolated Ag(+) ions. Owing to energy transfer from Ag(+) to RE ions, significant enhancements of RE ions emission (76 times for Sm(3+), 41 times for Dy(3+)) were observed for non-resonant UV excitation (255 nm). Our research may extend the understanding of interactions between RE ions and Ag species. © 2012 Optical Society of America

  6. Power dependent effects in the luminescence decay of GaAs/electrolyte contacts at the flat band potential

    Energy Technology Data Exchange (ETDEWEB)

    Kauffman, J.F.; Balko, B.A.; Richmond, G.L. [Univ. of Oregon, Eugene, OR (United States)

    1992-07-23

    Saturation of surface traps has been observed in the GaAs/Na{sub 2}-S photoelectrochemical system under modest excitation conditions. Saturation is shown to result in a surface minority trapping velocity that is dependent on time as well as laser excitation power. These saturation effects are observed by studying the luminescence decays of GaAs as a function of excitation pulse power under potentiostatic control at the flat band potential. The decays also indicate that surface minority carrier trapping is fast compared with processes which remove minority carriers from trap states. These results suggest that time-resolved experiments under high injection open circuit conditions may underestimate the surface minority trapping rate under typical solar conditions. 21 refs., 2 figs., 1 tab.

  7. The deformation stimulated luminescence in KCl, KBr and KI crystals

    Science.gov (United States)

    Shunkeyev, K.; Sergeyev, D.; Drozdowski, W.; Brylev, K.; Myasnikova, L.; Barmina, A.; Zhanturina, N.; Sagimbaeva, Sh; Aimaganbetova, Z.

    2017-05-01

    Currently, strengthening of the intensity of luminescence in alkali halide crystals (AHC) at lattice symmetry lowering is discussed as a promising direction for the development of scintillation detectors [1-3]. In this regard, for the study of anion excitons and radiation defects in the AHC anion sublattice at deformation, the crystals with the same sizes of cations and different sizes of anions were chosen. In the X-ray spectra of KCl at 10 K, the luminescence at 3.88 eV; 3.05 eV and 2.3 eV is clearly visible. The luminescence at 3.05 eV corresponds to the tunneling recharge [F*, H]. Luminescence at 3.88 eV is quenched in the region of thermal destruction of F‧-centers and characterizes tunneling recharge of F‧, VK-centers. In KCl at 90 K, the luminescence of self-trapped excitons (STE) is completely absent. In KBr at deformation not only STE luminescence, but also deformation stimulated luminescence at 3.58 eV were recorded, the last one corresponds to tunneling recharge of F‧, VK-centers. In KI crystal at 10 K and 90 K at deformation, only STE luminescence is enhanced. There are no deformation luminescence bands in KI compares with KBr and KCl crystals.

  8. Luminescence color as a characteristic for selection in poultry eggs

    Science.gov (United States)

    Rybalova, Natalya B.; Vasiljeva, Ludmilia T.; Zamorskaja, Tatjana; Bychajev, Al.

    1996-12-01

    This work concerns luminescence of egg shell and chick down and livability and egg production of hens. It was established that the best layers showed orange color of egg shell luminescence at the beginning of the laying period. Yellow color of chick down luminescence indicates on the chicken's good development especially concerning its digestive and circulatory systems, and connects with its future high livability and egg production. So the use of the color of luminescence is advisable as an additional characteristic providing good possibility to forecast the development of a chicken, its resistance for stressors, its livability and egg production afterwards.

  9. Dislocation luminescence in GaN single crystals under nanoindentation

    Science.gov (United States)

    2014-01-01

    This work presents an experimental study on the dislocation luminescence in GaN by nanoindentation, cathodoluminescence, and Raman. The dislocation luminescence peaking at 3.12 eV exhibits a series of special properties in the cathodoluminescence measurements, and it completely disappears after annealing at 500°C. Raman spectroscopy shows evidence for existence of vacancies in the indented region. A comprehensive investigation encompassing cathodoluminescence, Raman, and annealing experiments allow the assignment of dislocation luminescence to conduction-band-acceptor transition involving Ga vacancies. The nanoscale plasticity of GaN can be better understood by considering the dislocation luminescence mechanism. PMID:25593548

  10. Dislocation luminescence in GaN single crystals under nanoindentation.

    Science.gov (United States)

    Huang, Jun; Xu, Ke; Fan, Ying Min; Wang, Jian Feng; Zhang, Ji Cai; Ren, Guo Qiang

    2014-01-01

    This work presents an experimental study on the dislocation luminescence in GaN by nanoindentation, cathodoluminescence, and Raman. The dislocation luminescence peaking at 3.12 eV exhibits a series of special properties in the cathodoluminescence measurements, and it completely disappears after annealing at 500°C. Raman spectroscopy shows evidence for existence of vacancies in the indented region. A comprehensive investigation encompassing cathodoluminescence, Raman, and annealing experiments allow the assignment of dislocation luminescence to conduction-band-acceptor transition involving Ga vacancies. The nanoscale plasticity of GaN can be better understood by considering the dislocation luminescence mechanism.

  11. Luminescent Metal Nanoclusters for Potential Chemosensor Applications

    Directory of Open Access Journals (Sweden)

    Muthaiah Shellaiah

    2017-12-01

    Full Text Available Studies of metal nanocluster (M-NCs-based sensors for specific analyte detection have achieved significant progress in recent decades. Ultra-small-size (<2 nm M-NCs consist of several to a few hundred metal atoms and exhibit extraordinary physical and chemical properties. Similar to organic molecules, M-NCs display absorption and emission properties via electronic transitions between energy levels upon interaction with light. As such, researchers tend to apply M-NCs in diverse fields, such as in chemosensors, biological imaging, catalysis, and environmental and electronic devices. Chemo- and bio-sensory uses have been extensively explored with luminescent NCs of Au, Ag, Cu, and Pt as potential sensory materials. Luminescent bi-metallic NCs, such as Au-Ag, Au-Cu, Au-Pd, and Au-Pt have also been used as probes in chemosensory investigations. Both metallic and bi-metallic NCs have been utilized to detect various analytes, such as metal ions, anions, biomolecules, proteins, acidity or alkalinity of a solution (pH, and nucleic acids, at diverse detection ranges and limits. In this review, we have summarized the chemosensory applications of luminescent M-NCs and bi-metallic NCs.

  12. Na-rich feldspar as a luminescence dosimeter in infrared stimulated luminescence (IRSL) dating

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew; Jain, Mayank

    2013-01-01

    One of the challenges in dating rock surfaces is the choice of the luminescence mineral. Although quartz is the preferred dosimeter in sediment dating, it is often not sufficiently sensitive when extracted from solid rocks. The intensity of signals from feldspars tends to be much less dependent...... for measurement. This latter problem does not apply to Na-rich feldspar because of the absence of internal radioactivity.The potential application of Na-rich feldspar as a luminescence dosimeter for the IRSL dating of rock surfaces is investigated using a variety of sediment samples from different geological...... settings for which independent age control is available. The blue and yellow luminescence emissions are measured for IR stimulation at 50 °C (IR50), and post-IR IR stimulation at 290 °C (pIRIR290). Thermal stability experiments imply that the corresponding signals in both emissions have comparable thermal...

  13. Exotic nuclear excitations

    CERN Document Server

    Pancholi, S C

    2011-01-01

    By providing the reader with a foundational background in high spin nuclear structure physics and exploring exciting current discoveries in the field, this book presents new phenomena in a clear and compelling way. The quest for achieving the highest spin states has resulted in some remarkable successes which this monograph will address in comprehensive detail. The text covers an array of pertinent subject matter, including the rotational alignment and bandcrossings, magnetic rotation, triaxial strong deformation and wobbling motion and chirality in nuclei. Dr. Pancholi offers his readers a clearly-written and up-to-date treatment of the topics covered. The prerequisites for a proper appreciation are courses in nuclear physics and nuclear models and measurement techniques of observables like gamma-ray energies, intensities, multi-fold coincidences, angular correlations or distributions, linear polarization, internal conversion coefficients, short lifetime (pico-second range) of excited states etc. and instrum...

  14. Excitable scale free networks

    Science.gov (United States)

    Copelli, M.; Campos, P. R. A.

    2007-04-01

    When a simple excitable system is continuously stimulated by a Poissonian external source, the response function (mean activity versus stimulus rate) generally shows a linear saturating shape. This is experimentally verified in some classes of sensory neurons, which accordingly present a small dynamic range (defined as the interval of stimulus intensity which can be appropriately coded by the mean activity of the excitable element), usually about one or two decades only. The brain, on the other hand, can handle a significantly broader range of stimulus intensity, and a collective phenomenon involving the interaction among excitable neurons has been suggested to account for the enhancement of the dynamic range. Since the role of the pattern of such interactions is still unclear, here we investigate the performance of a scale-free (SF) network topology in this dynamic range problem. Specifically, we study the transfer function of disordered SF networks of excitable Greenberg-Hastings cellular automata. We observe that the dynamic range is maximum when the coupling among the elements is critical, corroborating a general reasoning recently proposed. Although the maximum dynamic range yielded by general SF networks is slightly worse than that of random networks, for special SF networks which lack loops the enhancement of the dynamic range can be dramatic, reaching nearly five decades. In order to understand the role of loops on the transfer function we propose a simple model in which the density of loops in the network can be gradually increased, and show that this is accompanied by a gradual decrease of dynamic range.

  15. Luminescence of water or ice as a new detection method for magnetic monopoles

    Directory of Open Access Journals (Sweden)

    Pollmann Anna Obertacke

    2017-01-01

    We present analysis techniques to use luminescence in neutrino telescopes and discuss experimental setups to measure the light yield of luminescence for the particular conditions in neutrino detectors.

  16. Quantum lattice fluctuations in a 1-dimensional charge-density-wave material: Luminescence and resonance Raman studies of an MX solid

    Energy Technology Data Exchange (ETDEWEB)

    Long, F.H.; Love, S.P.; Swanson, B.I.

    1993-02-01

    Luminescence spectra, both emission and excitation, and the excitation dependence of the resonance Raman (RR) spectra were measured for a 1-dimensional charge-density-wave solid, [Pt(L){sub 2}Cl{sub 2}][Pt(L){sub 2}](ClO{sub 4}){sub 4} ; L=1, 2-diaminoethane. The luminescence experiments support the existence of tail states in the band gap region, which indicate the presence of disorder. In contrast, the RR measurements conclusively demonstrated that the effects of static structural disorder on the vibrational spectroscopy can be neglected. This apparently paradoxical result can be explained by considering the zero-point motion of the lattice. The experimental results are compared to recent theoretical models.

  17. Luminescence detection of DNA-[Ru(bpy) 2tatp] 2+ conjugates on a polyaniline/ITO electrode associated with in situ electrochemical tuning

    Science.gov (United States)

    Shao, Jiangyang; Sun, Ting; Ji, Shibo; Li, Hong; Lan, Sheng; Xu, Zhenghe

    2010-05-01

    A new method for luminescence detection of [Ru(bpy) 2tatp] 2+-based thin layer (where bpy = 2,2'-bipyridine, tatp = 1,4,8,9-tetra-aza-triphenylene) on a polyaniline (PANI)/ITO electrode in the absence and presence of herring sperm DNA tuned by applied electrode potentials has been developed under the excitation of CW green laser. It is found that the DNA-[Ru(bpy) 2tatp] 2+ conjugates are formed either in solution or on the PANI/ITO surface, exhibiting an effective enhancement in the luminescence by DNA. More interestingly, the application of anodic potentials significantly enhances the emission intensities of both [Ru(bpy) 2tatp] 2+ and DNA-[Ru(bpy) 2tatp] 2+ conjugates on the PANI/ITO surface excited with green laser.

  18. Near-infrared luminescence of Bi2ZnOB2O6:Nd3+/PMMA composite

    Science.gov (United States)

    Jaroszewski, K.; Głuchowski, P.; Chrunik, M.; Jastrząb, R.; Majchrowski, A.; Kasprowicz, D.

    2018-01-01

    Near-infrared luminescence of a novel polymer composite system: PMMA doped with Bi2ZnOB2O6:Nd3+ microparticles, is reported for the first time. Luminescence properties of Bi2ZnOB2O6:Nd3+/PMMA were analyzed on the basis on excitation and emission spectra as well as fluorescence decay profiles. Excitation spectra monitored at 1062 nm (4F3/2 → 4I11/2) indicate numerous bands related to the optical transition of Nd3+ ions: from the 4I9/2 ground state to the 4D3/2, 2P1/2, 2K15/2, 4G7/2 + 4G9/2, 2K13/2, 4G5/2 + 2G7/2, 2H11/2, 4F9/2, 4F7/2 + 4S3/2, 4F5/2 + 2H9/2, 4F3/2 excited states. Many of them may be utilized to excite near-infrared emission of Nd3+ ions. In particular, distinctive Nd3+ emissions of the 4F3/2 → 4I9/2 and 4F3/2 → 4I11/2 transitions were detected, under excitation at 514 nm. The fluorescence decay profiles monitored at 1062 nm, excited at 514 nm, show relatively long emission lifetime of the 4F3/2 → 4I11/2 transition equal to 85 μs. Raman spectroscopy was used to determine vibrational properties and homogeneity of Bi2ZnOB2O6:Nd3+/PMMA composites. The obtained results suggest that Bi2ZnOB2O6:Nd3+/PMMA composite may be applied as an effective source of near-infrared emission in a new integrated optoelectronic devices.

  19. Laser-Induced Luminescence Study of Samarium(III) Thiodiglycolate Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Dong Yong; Lee, Eil Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kimura, Takaumi [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)

    2003-09-15

    The hydration number of Sm(III) has been obtained by using the difference in the decay rate constants in H{sub 2}O and D{sub 2}O solutions. In general, k{sub obs}(H{sub 2}O) >> k{sub obs}(D{sub 2}O), k{sub obs}(D{sub 2}O) ≅ constant, and ligands are not as effective in causing non-radiative de-excitation of the excited state. For Sm(III), a relationship has been proposed in which the hydration number is related directly to the decay rate constant in H{sub 2}O. If there is no contribution from the ligand to the de-excitation of the luminescence excited state, the hydration of Sm(III) in the different complexes can be obtained directly from the values of k{sub obs} measured in H{sub 2}O. The number and the geometric distribution of solvent molecules around a metal ion in solution are an important factor in the structural and chemical behavior of cation. Indeed, such information has been utilized to design novel ionophores and receptors. However, there have been few studies of hydration structure for lanthanides. The fact that many f-element salts which have relatively large lattice energies are fairly soluble in water is a reflection of the strength of the interactions between the metal cations and water molecules.

  20. Luminescent single-walled carbon nanotube-sensitized europium nanoprobes for cellular imaging

    Science.gov (United States)

    Avti, Pramod K; Sitharaman, Balaji

    2012-01-01

    Lanthanoid-based optical probes with excitation wavelengths in the ultra-violet (UV) range (300–325 nm) have been widely developed as imaging probes. Efficient cellular imaging requires that lanthanoid optical probes be excited at visible wavelengths, to avoid UV damage to cells. The efficacy of europium-catalyzed single-walled carbon nanotubes (Eu-SWCNTs), as visible nanoprobes for cellular imaging, is reported in this study. Confocal fluorescence microscopy images of breast cancer cells (SK-BR-3 and MCF-7) and normal cells (NIH 3T3), treated with Eu-SWCNT at 0.2 μg/mL concentration, showed bright red luminescence after excitation at 365 nm and 458 nm wavelengths. Cell viability analysis showed no cytotoxic effects after the incubation of cells with Eu-SWCNTs at this concentration. Eu-SWCNT uptake is via the endocytosis mechanism. Labeling efficiency, defined as the percentage of incubated cells that uptake Eu-SWCNT, was 95%–100% for all cell types. The average cellular uptake concentration was 6.68 ng Eu per cell. Intracellular localization was further corroborated by transmission electron microscopy and Raman microscopy. The results indicate that Eu-SWCNT shows potential as a novel cellular imaging probe, wherein SWCNT sensitizes Eu3+ ions to allow excitation at visible wavelengths, and stable time-resolved red emission. The ability to functionalize biomolecules on the exterior surface of Eu-SWCNT makes it an excellent candidate for targeted cellular imaging. PMID:22619533

  1. SPECTRAL-LUMINESCENT CHARACTERISTICS OF FLUOROPHOSPHATE GLASSES ACTIVATED WITH MANGANESE AND CADMIUM SULPHIDE QUANTUM DOTS

    Directory of Open Access Journals (Sweden)

    Zhanna O. Lipatova

    2014-11-01

    Full Text Available Research and development of phosphors based on quantum dots (QD is a perspective problem of photonics. The main advantages of fluorophosphate glass with quantum dots are: high absorption coefficient, solid matrix and a broad band luminescence with high quantum efficiency of QD. Manganese ions have an intense band luminescence in the red region of the spectrum. Thus, the addition of manganese ions in the glass with quantum dots leads to a broadening of the spectrum in the long wavelength region. Such emission is closer to natural sunlight and has a high color rendering index. The work objective is the study of the spectral and luminescent properties of fluorophosphate glasses doped with manganese and CdS quantum dots. Fluorophosphate glasses (47NaPO3-30H3PO4-10Ga2O3-5ZnO-xMnS-7,5NaALF6-4,2CdS, where x = 3, 6, 8 mol. % were synthesized. The secondary heat treatment at the temperature of 430 ° C for 90 minutes has led to the growth of quantum dots in glass volume. Absorption spectra have been measured in the visible range (from 300 to 600 nm. Heat treatment has led to a shift of the fundamental absorption edge in the visible region of the spectrum. This change is due to the growth of quantum dots. Maximum intensity of luminescence is shifted to the red region of the spectrum from 620 nm to 660 nm under laser excitation at 410 nm. The maximum shift was observed in the glass with a concentration of 3 mol. % of manganese, the minimum one - in the glass with a concentration of 8 mol. %. Values of manganese ions lifetime from18 ms for a sample with a concentration of MnS 3 mol. % to15 ms for MnS 8 mol % were obtained. The decrease in the lifetime with concentration increasing of manganese ions is due to the concentration quenching of the luminescence. The growth of CdS quantum dots in the heat treatment leads to a decrease of the lifetimes to the values below 9-3 ms (3 and 8 - mol. % MnS, respectively. Obtained findings prove that fluorophosphate

  2. Blue-emissive upconversion nanoparticles for low-power-excited bioimaging in vivo.

    Science.gov (United States)

    Liu, Qian; Yang, Tianshe; Feng, Wei; Li, Fuyou

    2012-03-21

    Water-soluble upconversion luminescent (UCL) nanoparticles based on triplet-triplet annihilation (TTA) were successfully prepared by coloading sensitizer (octaethylporphyrin Pd complex) and annihilator (9,10-diphenylanthracene) into silica nanoparticles. The upconversion luminescence quantum yield of the nanoparticles can be as high as 4.5% in aqueous solution. As determined by continuous kinetic scan, the nanoparticles have excellent photostability. Such TTA-based upconversion nanoparticles show low cytotoxicity and were successfully used to label living cells with very high signal-to-noise ratio. UCL imaging with the nanoparticles as probe is capable of completely eliminating background fluorescence from either endogenous fluorophores of biological sample or the colabeled fluorescent probe. In particular, such blue-emissive upconversion nanoparticles were successfully applied in lymph node imaging in vivo of living mouse with excellent signal-to-noise ratio (>25), upon low-power density excitation of continuous-wave 532 laser (8.5 mW cm(-2)). Such high-contrast and low-power excited bioimaging in vivo with a blue-emissive upconversion nanoparticle as probe may extend the arsenal of currently available luminescent bioimaging in vitro and in vivo.

  3. Synthesis, characterization and luminescence of europium perchlorate with MABA-Si complex and coating structure SiO2@Eu(MABA-Si) luminescence nanoparticles.

    Science.gov (United States)

    Fu, Zhi-Fang; Li, Wen-Xian; Bai, Juan; Bao, Jin-Rong; Cao, Xiao-Fang; Zheng, Yu-Shan

    2017-05-01

    This article reports a novel category of coating structure SiO 2 @Eu(MABA-Si) luminescence nanoparticles (NPs) consisting of a unique organic shell, composed of perchlorate europium(III) complex, and an inorganic core, composed of silica. The binary complex Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O was synthesized using HOOCC 6 H 4 N(CONH(CH 2 ) 3 Si(OCH 2 CH 3 ) 3 ) 2 (MABA-Si) and was used as a ligand. Furthermore, the as-prepared silica NPs were successfully coated with the -Si(OCH 2 CH 3 ) 3 group of MABA-Si to form Si-O-Si chemical bonds by means of the hydrolyzation of MABA-Si. The binary complexes were characterized by elemental analysis, molar conductivity and coordination titration analysis. The results indicated that the composition of the binary complex was Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O. Coating structure SiO 2 @Eu(MABA-Si) NPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared (IR) spectra. Based on the SEM and TEM measurements, the diameter of core-SiO 2 particles was ~400 and 600 nm, and the thickness of the cladding layer Eu(MABA-Si) was ~20 nm. In the binary complex Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O, the fluorescence spectra illustrated that the energy of the ligand MABA-Si transferred to the energy level for the excitation state of europium(III) ion. Coating structure SiO 2 @Eu(MABA-Si) NPs exhibited intense red luminescence compared with the binary complex. The fluorescence lifetime and fluorescence quantum efficiency of the binary complex and of the coating structure NPs were also calculated. The way in which the size of core-SiO 2 spheres influences the luminescence was also studied. Moreover, the luminescent mechanisms of the complex were studied and explained. Copyright © 2016 John Wiley & Sons, Ltd.

  4. The effect of furcated hydrogen bond and coordination bond on luminescent behavior of metal-organic framework [CuCN·EIN]: a TDDFT study.

    Science.gov (United States)

    Wu, Danyang; Mi, Weihong; Ji, Min; Hao, Ce; Qiu, Jieshan

    2012-11-01

    The hydrogen bonding in electronically excited-state of the metal-organic framework [CuCN·EIN] was studied using time-dependent density functional theory (TDDFT). The representative fragment of [CuCN·EIN] was employed for the computation. The geometric structures, binding energies and IR spectra in both ground state and electronically excited state S(1) of the complex were computed using DFT and TDDFT methods to investigate excited-state hydrogen-bonding and coordination bonding, respectively. Based on the analysis of the frontier molecular orbitals and the electronic configuration of the complex, the ligand-to-metal charge transfer (LMCT) luminescence was confirmed. Furthermore, furcated hydrogen bonds are both strengthened in the S(1) state slightly. And then, the strengthening of the hydrogen bonds in the S(1) state goes against the charge transfer from ligand to metal and then should be in favor of the luminescence. In particular, we also discuss strengthening or weakening behavior of the coordination bonds in the S(1) state for the first time. Based on the results of the bond lengths and vibration frequency of the coordination bond, we can conclude that the coordination bond Cu(7)-N(8) is strengthened in the S(1) state. And the strengthening of the coordination bond Cu(7)-N(8) should also be in favor of the luminescence. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Luminescent properties of Ce{sup 3+}ions in Ca {sub 2}B {sub 5}O {sub 9}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, V.P.; Berezovskaya, I.V.; Efryushina, N.P.; Shabanov, E.V. [A.V. Bogatsky Physico-Chemical Institute, Ukrainian Academy of Sciences, Lustdorfskaya doroga 86, 65080 Odessa (Ukraine); Voloshinovskii, A.S. [Lviv Franko State University, Kirilo i Mefodii 8, 79005 Lviv (Ukraine)

    2006-04-15

    The luminescent properties of Ce{sup 3+} ions in Ca{sub 2}B{sub 5}O{sub 9}Cl have been studied upon excitation in the 3.5-25 eV region. The energies of all 5d crystal field levels of Ce{sup 3+} ions in double doped Ca{sub 2}B{sub 5}O{sub 9}Cl:Ce{sup 3+}, Na{sup +} have been determined. In addition to the 4f {yields} 5d excitation bands, the excitation spectrum of the Ce{sup 3+} emission shows a band with a maximum at 7.7 eV, which is attributed to the absorption of the borate groups. The influence of the structural features of Ca{sub 2}B{sub 5}O{sub 9}Cl on the luminescent behavior of Ce{sup 3+} is discussed. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Tuning luminescence intensity of RHO6G dye using silver ...

    Indian Academy of Sciences (India)

    The photoluminescence (PL) from rhodamine (RHO6G) dye dispersed in ethanol has been studied in the presence of different amounts of citrate stabilized silver nanoparticles of size, ∼10 nm. Enhancement as well as quenching of luminescence intensity has been observed and it was found that luminescence intensity can ...

  7. Performance of Harshaw 6600 thermo-luminescence dosimeter (TLD)

    African Journals Online (AJOL)

    Performance of Harshaw 6600 thermo-luminescence dosimeter (TLD) system for personal monitoring. ... Fading of 19 % of thermo-luminescence (TL) readout was observed in 90 days when TLD chips were stored at room temperature (~ 27º C). The TL sensitivities of chips in three holder types were close to that for Cs-137 ...

  8. Tuning Luminescent Converters Based on Coumarins and Their Photostability

    Science.gov (United States)

    Tsaplev, Yu. B.; Trofimov, A. V.; Pershukevich, P. P.; Pavich, T. A.; Zak, P. P.; Trofimova, N. N.; Lapina, V. A.

    2017-11-01

    We have studied the feasibility of using luminophores in the coumarin series in luminescent filters for correcting the spectra of light-emitting diode (LED) light sources. Fine tuning of the emission spectra of luminophores in polymer matrices is achieved by introducing nonionic surfactants into the matrix. We propose a method for estimating the photostability of luminescent filters and we determine the photostability parameters.

  9. Effect of second ligand on the luminescence of Samarium (III ...

    Indian Academy of Sciences (India)

    Effect of second ligand on the luminescence of Samarium (III) dibenzoylmethane complexes: Syntheses, crystal structures, thermal analysis and luminescence study. MUHAMMAD IDIRIS SALEH, MIN YEE CHOO, TAI WEI CHAN and MOHD R RAZALI. ∗. School of Chemical Sciences, Universiti Sains Malaysia, Penang, ...

  10. Luminescence imaging using radionuclides: a potential application in molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Chan [Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 700-422 (Korea, Republic of); Il An, Gwang [Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Park, Se-Il [Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 700-422 (Korea, Republic of); Oh, Jungmin [Korea Basic Science Institute Chuncheon Center, Gangwon-do 200-701 (Korea, Republic of); Kim, Hong Joo [Department of Physics and Energy Science, Kyungpook National University, Daegu 702-710 (Korea, Republic of); Su Ha, Yeong; Wang, Eun Kyung [Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 700-422 (Korea, Republic of); Min Kim, Kyeong; Kim, Jung Young [Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Lee, Jaetae [Department of Nuclear Medicine, School of Medicine, Kyungpook National University, Daegu 700-422 (Korea, Republic of); Welch, Michael J. [Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Yoo, Jeongsoo, E-mail: yooj@knu.ac.k [Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 700-422 (Korea, Republic of)

    2011-04-15

    Introduction: Nuclear and optical imaging are complementary in many aspects and there would be many advantages when optical imaging probes are prepared using radionuclides rather than classic fluorophores, and when nuclear and optical dual images are obtained using single imaging probe. Methods: The luminescence intensities of various radionuclides having different decay modes have been assayed using luminescence imaging and in vitro luminometer. Radioiodinated Herceptin was injected into a tumor-bearing mouse, and luminescence and microPET images were obtained. The plant dipped in [{sup 32}P]phosphate solution was scanned in luminescence mode. Radio-TLC plate was also imaged in the same imaging mode. Results: Radionuclides emitting high energy {beta}{sup +}/{beta}{sup -} particles showed higher luminescence signals. NIH3T6.7 tumors were detected in both optical and nuclear imaging. The uptake of [{sup 32}P]phosphate in plant was easily followed by luminescence imaging. Radio-TLC plate was visualized and radiochemical purity was quantified using luminescence imaging. Conclusion: Many radionuclides with high energetic {beta}{sup +} or {beta}{sup -} particles during decay were found to be imaged in luminescence mode due mainly to Cerenkov radiation. 'Cerenkov imaging' provides a new optical imaging platform and an invaluable bridge between optical and nuclear imaging. New optical imaging probes could be easily prepared using well-established radioiodination methods. Cerenkov imaging will have more applications in the research field of plant science and autoradiography.

  11. Bright stable luminescent yeast using bacterial luciferase as a sensor.

    NARCIS (Netherlands)

    Szittner, R; Jansen, G.; Thomas, DY; Meighen, E

    2003-01-01

    24h while luminescence of yeast with decanal decayed to less than 0.01% of that with Z-9-tetradecenal after 2min. Moreover, yeast survived in 0.5% (v/v) Z-9-tetradecenal while 0.005% (v/v) decanal was lethal. Luminescence of yeast (+luxAB) was also stimulated 100-fold by transformation with the

  12. Enhanced multi-spectral imaging of live breast cancer cells using immunotargeted gold nanoshells and two-photon excitation microscopy

    Science.gov (United States)

    Bickford, Lissett; Sun, Jiantang; Fu, Kun; Lewinski, Nastassja; Nammalvar, Vengadesan; Chang, Joseph; Drezek, Rebekah

    2008-08-01

    We demonstrate the capability of using immunotargeted gold nanoshells as contrast agents for in vitro two-photon microscopy. The two-photon luminescence properties of different-sized gold nanoshells are first validated using near-infrared excitation at 780 nm. The utility of two-photon microscopy as a tool for imaging live HER2-overexpressing breast cancer cells labeled with anti-HER2-conjugated nanoshells is then explored and imaging results are compared to normal breast cells. Five different imaging channels are simultaneously examined within the emission wavelength range of 451-644 nm. Our results indicate that under near-infrared excitation, superior contrast of SK-BR-3 cancer cells labeled with immunotargeted nanoshells occurs at an emission wavelength ranging from 590 to 644 nm. Luminescence from labeled normal breast cells and autofluorescence from unlabeled cancer and normal cells remain imperceptible under the same conditions.

  13. Enhanced multi-spectral imaging of live breast cancer cells using immunotargeted gold nanoshells and two-photon excitation microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bickford, Lissett; Sun Jiantang; Fu, Kun; Lewinski, Nastassja; Nammalvar, Vengadesan; Chang, Joseph; Drezek, Rebekah [Department of Bioengineering, Rice University, Houston, TX 77005 (United States)], E-mail: drezek@rice.edu

    2008-08-06

    We demonstrate the capability of using immunotargeted gold nanoshells as contrast agents for in vitro two-photon microscopy. The two-photon luminescence properties of different-sized gold nanoshells are first validated using near-infrared excitation at 780 nm. The utility of two-photon microscopy as a tool for imaging live HER2-overexpressing breast cancer cells labeled with anti-HER2-conjugated nanoshells is then explored and imaging results are compared to normal breast cells. Five different imaging channels are simultaneously examined within the emission wavelength range of 451-644 nm. Our results indicate that under near-infrared excitation, superior contrast of SK-BR-3 cancer cells labeled with immunotargeted nanoshells occurs at an emission wavelength ranging from 590 to 644 nm. Luminescence from labeled normal breast cells and autofluorescence from unlabeled cancer and normal cells remain imperceptible under the same conditions.

  14. High efficiency white luminescence in Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} tri-doped oxyfluoride glass ceramic microsphere pumped by 976 nm laser

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jing; Huang, Yantang, E-mail: huangyantang@fzu.edu.cn; Wu, Tianjiao; Huang, Yu; Zhang, Peijin

    2015-01-15

    In this paper, transparent Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} tri-doped oxyfluoride glass ceramic samples containing LaF{sub 3} nanocrystals were prepared by a melt quenching method, and were subsequently fabricated into transparent microspheres with handles. A new method to study the luminescent properties of Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} tri-doped oxyfluoride glass ceramic was proposed, which was using the biconical tapered fiber-microsphere coupled structure. The structure has characteristics of low excitation optical power, easy preparation and convenient testing. We obtained strong white light including the blue (471 nm), green (523 nm and 544 nm) and red (651 nm) emission under the excitation of a 976 nm laser diode (LD) and the relationship of the luminous flux of white light versus pump power simultaneously. In addition, the up-conversion (UC) luminescence mechanism of rare earth (RE) ions and the reason of high luminescence efficiency in our experiment were also explained. The white light obtained by UC of 976 nm laser has more advantages than that by down-conversion of blue light. It may be applied in many fields such as background light, lighting, etc. - Highlights: • A new method to study the luminescent properties of glass materials is proposed. • The white light was obtained by up-conversion of 976 nm laser. • The mechanism of up-conversion luminescence was clearly explained. • The advantages of the white luminescence excited by 976 nm were reported.

  15. Luminescence and white-light emitting luminescent sensor of tetrafluoroterephthalate-lanthanide metal-organic frameworks.

    Science.gov (United States)

    Han, Yongqiang; Yan, Pengfei; Sun, Jingwen; An, Guanghui; Yao, Xu; Li, Yuxin; Li, Guangming

    2017-04-05

    Two types of sixteen complexes 1-16, namely, {[Ln(TFBDC)1.5(H2O)]·2H2O}n [Ln = Pr (1) and Nd (2)] and {[Ln(TFBDC)1.5(H2O)2]·H2O}n [Ln = Ce (3), Pr (4), Nd (5), Sm (6), Eu (7), Gd (8), Tb (9), Dy (10), Ho (11), Er (12), Yb (13) and Lu (14)], {[Dy0.281Eu0.719(TFBDC)1.5(H2O)2]·H2O}n (15) and {[Gd0.871Eu0.103Tb0.026(TFBDC)1.5(H2O)2]·H2O}n (16), were isolated by the reaction of LnCl3·6H2O with 2,3,5,6-tetrafluoroterephthalic acid (H2TFBDC). X-ray crystallographic analysis revealed that 1 and 2 exhibit 3D network structures and complexes 3-14 feature 2D network structures formed via three different coordination modes of the ligand. Luminescence spectra revealed that these complexes exhibit broad-spectrum luminescence from the visible to the near-infrared (NIR) region. Unexpectedly, complex 1 exhibits a unique NIR luminescence pattern and the longest lifetime among reported molecular praseodymium complexes. White-light emission was realized via three approaches using the single-component complex 6 (Sm), the two-component complex 15 (Eu and Dy) and the three-component complex 16 (Eu, Tb and Gd). Complex 9 exhibits high sensitivity and selectivity in its luminescence response to benzaldehyde, which provides a promising luminescent sensor for the detection of benzaldehyde.

  16. White light source with laser-excited phosphor

    Science.gov (United States)

    Abdullaev, O. R.; Aluev, A. V.; Akhmerov, Yu. L.; Kourova, N. V.; Mezhennyi, M. V.; Chelny, A. A.

    2017-11-01

    The principles of operation of a white light source based on a remote phosphor, made of cerium-doped yttrium aluminium garnet (YAG : Ce3+), whose luminescence is excited by a blue laser diode, are considered. The colorimetric and photometric characteristics of phosphors of different types are analysed as functions of the phosphor film thickness. The following parameters are obtained at an output power of 1 W and a wavelength of 445±3 nm in the cw regime: luminous flux of 165 lm, correlated colour temperature of 5595 K, colour rendering index of 66, colour coordinates x = 0.3303 and y = 0.3427, luminous efficiency of 165 lm W‑1, and light efficacy of 30 lm W‑1. These characteristics are comparable with similar parameters of commercial white LEDs.

  17. Persistent luminescent sub-10 nm Cr doped ZnGa2O4 nanoparticles by a biphasic synthesis route.

    Science.gov (United States)

    Srivastava, Bhupendra B; Kuang, Anxiu; Mao, Yuanbing

    2015-04-30

    This communication highlights a simple and facile biphasic synthesis of sub-10 nm Cr doped ZnGa2O4 nanoparticles (NPs) for the first time. These smallest Cr:ZnGa2O4 NPs demonstrate stable persistent luminescence emission more than 40 min after excitation. This synthesis strategy not only enables the controlled synthesis of these mixed metal oxide NPs unprecedentedly with smallest size to date but also allows them to be solution processable, which is advantageous for relevant applications with feasible and economic device fabrication.

  18. Luminescence Materials as Nanoparticle Thermal Sensors

    Science.gov (United States)

    2016-06-01

    6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-16-71 Luminescence Materials as Nanoparticle Thermal Sensors ...10 12 joule (J) British thermal unit (Btu) (thermochemical) 1.054 350 × 10 3 joule (J) foot-pound-force (ft lbf) 1.355 818 joule (J) calorie...theoretical investigations on thermal history extraction III. Materials Testing TL in te ns ity Temperature (K) te m pe ra tu re time • nanophosphors

  19. Thermal luminescence spectroscopy chemical imaging sensor.

    Science.gov (United States)

    Carrieri, Arthur H; Buican, Tudor N; Roese, Erik S; Sutter, James; Samuels, Alan C

    2012-10-01

    The authors present a pseudo-active chemical imaging sensor model embodying irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. We elaborate on various optimizations, simulations, and animations of the integrated sensor design and apply it to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor must measure and process a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully.

  20. Laser-induced luminescence in hybrid nanofilms

    Science.gov (United States)

    Saifutyarov, R. R.; Khomyakov, A. V.; Akkuzina, A. A.; Avetisov, R. I.; Petrova, O. B.; Avetisov, I. Kh.; Kravchenko, S. V.

    2015-07-01

    Tris(8-hydroxyquinoline) boron (Bq3) was synthesized by a high-temperature exchange reaction. Bq3 powders containing various polymorphous modifications were synthesized, and their photoluminescent characteristics were analyzed. Films of Alq3/B2O3/Al hybrid materials (HMs) were deposited on glass substrates by vacuum thermal evaporation. It is shown that local heating by a diode laser (785 nm) with an intensity of 150 W/cm2 for one second causes irreversible transformation in the HM film structure. The chromaticity coordinates of the photoluminescence of laser-irradiated regions considerably differ from those of the initial HM film luminescence.

  1. Development of novel edible luminescent nanoparticle sensors

    Science.gov (United States)

    Jalalian, Sanaz

    This project has developed a novel class of edible hydrocolloid food nanosensors which are doped with luminescent chromophores and investigated whether they can be used to provide information about the local food matrix - temperature, oxygen concentration, and the presence of food-borne pathogens. The luminescence properties of the probes such as phosphorescence and fluorescence provide the sensor sensitivity to the food properties. Hydrocolloid nanoparticles were made from gelatin and starch with diameters ranging from 50 to ˜200 nm and labeled with food grade luminescent probes. The chromophore was covalently and non-covalently attached to the nanoparticle and the photophysical properties of the probe in the food system were studied. Temperature sensors were developed by using the phosphorescence sensitivity of a chromophore to temperature. Experiments with two different probes, namely erythrosine B labeled gelatin nanoparticles and phloxine B labeled gelatin nanoparticles have demonstrated that both probes can be effectively used as temperature sensors in liquid and solid food. The Van't Hoff plots of ln(IDF/IP) versus 1/T vary monotonically over a relatively wide temperature range and thus provide a basis for estimating temperature from measurements of phosphorescence and delayed fluorescence. The tests indicated that the presence of some ingredients such as tannin and anthocyanins in the composition of the food may prohibit the use of gelatin nanoparticle probes due to precipitation of gelatin nanoparticles. The luminescence quenching of the probe by oxygen was used to develop a nanoparticle sensor for oxygen. The results of experiments on liquid and solid food samples indicate that erythrosine B labeled gelatin nanoparticles can be used as a probe to detect the presence or absence of oxygen in some liquid foods. Precise control of oxygen concentration in solutions will pose a challenge as has been observed in this study. The probe did not work as an

  2. Research Update: Luminescence in lead halide perovskites

    Directory of Open Access Journals (Sweden)

    Ajay Ram Srimath Kandada

    2016-09-01

    Full Text Available Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  3. Fast field-induced dissociation and recombination of optical excitations in a pi-conjugated polymer

    CERN Document Server

    Lupton, J M; Baessler, H

    2003-01-01

    We present time resolved photoluminescence measurements on thin films of a phenyl-substituted poly(phenylene-vinylene) incorporated in a diode structure. Under reverse bias conditions rapid exciton dissociation is observed leading to luminescence quenching by up to 30%. In contrast, under forward bias conditions the initial quenching is substantially reduced due to shielding by space charges. At longer times thermally activated exciton quenching by injected polarons dominates the quenching process. At 3 ns after excitation, the external field is found to enhance the delayed luminescence. We attribute this to increased recombination of spatially correlated charge carrier pairs in the presence of the electric field, which are generated by exciton dissociation by bimolecular annihilation or on defect states.

  4. Preparation, and characterizations of a novel luminescence Lu{sub 2}WO{sub 6}:Eu{sup 3+} film as potential scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiang-Yang [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Zhang, Zhi-Jun, E-mail: zhangzj@mail.sic.ac.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhu, Lin-Lin; Xu, Meng [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Wang, Hong [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai 200050 (China); Li, Ai-Guo [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); Zhao, Jing-Tai, E-mail: jtzhao@shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

    2014-10-30

    Graphical abstract: - Highlights: • Novel Lu{sub 2}WO{sub 6}:Eu{sup 3+} luminescence films with micron-thickness were first fabricated on Si (1 0 0) wafer by a chemical route. • Lu{sub 2}WO{sub 6}:Eu{sup 3+} films with dense and homogeneous morphology exhibit good scintillation properties. • Luminescence mechanism associated with Eu{sup 3+} site occupation and possible energy transfer of Lu{sub 2}WO{sub 6}:Eu{sup 3+} films have also been proposed. • A new method of hydrophilizing Si (1 0 0) wafers without HF is proposed. - Abstract: Novel Lu{sub 2}WO{sub 6}:Eu{sup 3+} films with excellent luminescence performance were successfully prepared by Pechini method for the first time and characterized with X-ray diffraction (XRD), micro X-ray fluorescence imaging (μ-XRF), atomic force microscope (AFM), and X-ray excited luminescence (XEL), etc. Eu{sup 3+}-doped films emitted strong red light peak wavelength at 612 nm under both UV light or X-ray excitation. The optimal annealing temperature and Eu{sup 3+}-doped concentration are around 950 °C and 10 mol%, respectively. In addition, luminescence mechanism associated with Eu{sup 3+} site occupation and possible energy transfer of Lu{sub 2}WO{sub 6}:Eu{sup 3+} films have also been proposed. The optimized thin film shows great potential for applications as a candidate for X-ray imaging due to its high density, suitable emission wavelength and high light yield.

  5. Energy levels in YPO{sub 4}:Ce{sup 3+},Sm{sup 3+} studied by thermally and optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Bos, Adrie J.J., E-mail: a.j.j.bos@tudelft.n [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Poolton, Nigel R.J. [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Institute of Maths and Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom); Wallinga, Jakob [Netherlands Centre for Luminescence Dating, Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands); Bessiere, Aurelie [Ecole Nat. Superieure de Chimie de Paris, 11 Rue P et M Curie, 75231 Paris Cedex 05 (France); Dorenbos, Pieter [Delft University of Technology, Mekelweg 15, NL 2629 JB Delft (Netherlands)

    2010-03-15

    Energy-resolved optically stimulated luminescence (OSL) spectra and thermoluminescence (TL) glow curves of a powder sample of YPO{sub 4}:Ce{sup 3+},Sm{sup 3+} were measured to investigate the nature of the trapping centre and to locate its energy level relative to the valence and conduction bands of the YPO{sub 4} host. The high-temperature glow peak could unequivocally be assigned to Sm{sup 2+} (thus Sm{sup 3+} acts as an electron trap). The trap depth of this centre, as derived from the OSL excitation spectra, is in good agreement with the Dorenbos model prediction. The OSL excitation spectra also reveal excited states of Sm{sup 2+} well below the conduction band. These excited states produce a broadening of the high-temperature TL glow peak and also cause the activation energy determined by the Hoogenstraten method to underestimate the trap depth.

  6. Visualization of hot spot formation in energetic materials under periodic mechanical excitation using phosphor thermography

    Science.gov (United States)

    Casey, Alex; Fenoglio, Gabriel; Detrinidad, Humberto

    2017-06-01

    Under mechanical excitation, energy is known to localize within an energetic material resulting in `hot spot' formation. While many formation mechanisms have been proposed, additional insight to heat generation mechanisms, the effect of binder/crystal interfaces, and predication capabilities can be gained by quantifying the initiation and growth of the hot spots. Phosphor thermography is a well established temperature sensing technique wherein an object's temperature is obtained by collecting the temperature dependent luminescence of an optically excited phosphor. Herein, the phosphor thermography technique has been applied to Dow Corning Sylgard® 184/octahydro 1,3,5,7 tetranitro 1,3,5,7 tetrazocine (HMX) composite materials under mechanical excitation in order to visualize the evolution of the temperature field, and thus hot spot formation, within the binder. Funded by AFOSR. Supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

  7. Luminescence properties of Ga-graded Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haarstrich, J., E-mail: jakob.haarstrich@uni-jena.de [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Metzner, H.; Ronning, C. [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Undisz, A. [Institut fuer Materialwissenschaft und Werkstofftechnologie, Metallische Werkstoffe, Friedrich-Schiller-Universitaet Jena, Loebdergraben 32, 07743 Jena (Germany); Rissom, T.; Kaufmann, C.A.; Schock, H.W. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Solar Energy Research, Institute for Technology, Lise-Meitner-Campus, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2012-02-29

    Cathodoluminescence (CL) has been measured at 10 K in cross-section and plan-view configuration on Cu(In,Ga)Se{sub 2} thin films with Ga-grading as they are used in high-efficiency solar cells. Measurements on cross-section samples show the vertical profile of the emission energy to correspond to the band-gap profile of the film as calculated from measurements of the Ga-grading. Hence, the CL method is capable to directly measure the band-gap grading in semiconductor thin-films, but often the influence of the grading on the emission energy is generally ignored in recent literature. At the same time, we observe a strong drift of excited charge carriers toward the minimum of the band-gap. The transport process can be explained by the quasi-electric field induced by the Ga-grading and applied to determine transport properties of the Cu(In,Ga)Se{sub 2} material. Implications for luminescence investigations on band-gap graded thin-films are discussed. - Highlights: Black-Right-Pointing-Pointer The influence of Ga-grading on the luminescence of Cu(In,Ga)Se{sub 2} (CIGS) films is investigated. Black-Right-Pointing-Pointer The emission energies from Ga-graded CIGS films correspond to the local band-gaps. Black-Right-Pointing-Pointer The band-gap grading is measured using monochromatic cathodoluminescence cross section imaging. Black-Right-Pointing-Pointer Charge carrier drift to the band-gap minimum is observed and described in a model. Black-Right-Pointing-Pointer Ignoring grading related effects leads to misinterpretation of luminescence data.

  8. Radiance limits of ceramic phosphors under high excitation fluxes

    Science.gov (United States)

    Lenef, Alan; Kelso, John; Zheng, Yi; Tchoul, Maxim

    2013-09-01

    Ceramic phosphors, excited by high radiance pump sources, offer considerable potential for high radiance conversion. Interestingly, thermodynamic arguments suggest that the radiance of the luminescent spot can even exceed that of the incoming light source. In practice, however, thermal quenching and (non-thermal) optical saturation limit the maximum attainable radiance of the luminescent source. We present experimental data for Ce:YAG and Ce:GdYAG ceramics in which these limits have been investigated. High excitation fluxes are achieved using laser pumping. Optical pumping intensities exceeding 100W/mm2 have been shown to produce only modest efficiency depreciation at low overall pump powers because of the short Ce3+ lifetime, although additional limitations exist. When pump powers are higher, heat-transfer bottlenecks within the ceramic and heat-sink interfaces limit maximum pump intensities. We find that surface temperatures of these laser-pumped ceramics can reach well over 150°C, causing thermal-quenching losses. We also find that in some cases, the loss of quantum efficiency with increasing temperature can cause a thermal run-away effect, resulting in a rapid loss in converted light, possibly over-heating the sample or surrounding structures. While one can still obtain radiances on the order of many W/mm2/sr, temperature quenching effects ultimately limit converted light radiance. Finally, we use the diffusion-approximation radiation transport models and rate equation models to simulate some of these nonlinear optical pumping and heating effects in high-scattering ceramics.

  9. X-ray luminescence computed tomography: a sensitivity study

    Science.gov (United States)

    Lun, Michael C.; Zhang, Wei; Li, Changqing

    2017-03-01

    X-ray luminescence computed tomography (XLCT) is a hybrid molecular imaging modality that uses high energy x-ray photons to excite nanophosphors (e.g. Europium doped Gadolinium Oxysulfide - GOS: Eu3+) emitting optical photons to be measured by a sensitive detector for image reconstruction. XLCT has potentials to combine both the merits of x-ray imaging (high spatial resolution) and optical imaging (high sensitivity), which makes XLCT an attractive imaging modality to image nanophosphor targets deeply embedded in turbid media. In this study, we have evaluated the sensitivity of XLCT with phantom experiments by scanning targets of different phosphor concentrations at different depths. Cylindrical phantoms embedded with a cylindrical target with varying concentrations of GOS: Eu3+ (27.6 mM, 2.76 mM, 276 μM, and 27.6 μM) were scanned inside our lab made XLCT imaging system for varying scanning depths (6, 11, 16, and 21 mm). We found that XLCT is capable of imaging targets of very low concentrations (27.6 μM or 0.01 mg/mL) at significant depths, such as 21 mm. Our results demonstrate that there is also little variation in the reconstructed target size for different imaging depths for XLCT. We have for the first time, compared the sensitivity of XLCT with that of traditional computed tomography (CT) for phosphor targets. We found that XLCT's use of x-ray induced photons provides much higher measurement sensitivity and contrast compared to CT which provides image contrast solely based on x-ray attenuation.

  10. CINE: Comet INfrared Excitation

    Science.gov (United States)

    de Val-Borro, Miguel; Cordiner, Martin A.; Milam, Stefanie N.; Charnley, Steven B.

    2017-08-01

    CINE calculates infrared pumping efficiencies that can be applied to the most common molecules found in cometary comae such as water, hydrogen cyanide or methanol. One of the main mechanisms for molecular excitation in comets is the fluorescence by the solar radiation followed by radiative decay to the ground vibrational state. This command-line tool calculates the effective pumping rates for rotational levels in the ground vibrational state scaled by the heliocentric distance of the comet. Fluorescence coefficients are useful for modeling rotational emission lines observed in cometary spectra at sub-millimeter wavelengths. Combined with computational methods to solve the radiative transfer equations based, e.g., on the Monte Carlo algorithm, this model can retrieve production rates and rotational temperatures from the observed emission spectrum.

  11. Luminescence quenching and scintillation response in the Ce3+ doped GdxY3-xAl5O12 (x = 0.75, 1, 1.25, 1.5, 1.75, 2) single crystals

    Science.gov (United States)

    Bartosiewicz, K.; Babin, V.; Kamada, K.; Yoshikawa, A.; Mares, J. A.; Beitlerova, A.; Nikl, M.

    2017-01-01

    The luminescence and scintillation properties of the gadolinium yttrium aluminium garnets, (Gd,Y)3Al5O12 doped with Ce3+ are investigated as a function of the Gd/Y ratio with the aim of an improved understanding of the luminescence quenching, energy transfer and phase stability in these materials. An increase of both crystal field strength and instability of the garnet phase with increasing content of Gd3+ is observed. The instability of the garnet phase results in an appearance of the perovskite phase inclusions incorporated into the garnet phase. The luminescence features of Ce3+ in the perovskite phase inclusions and in the main garnet phase are studied separately. The thermal quenching of the 5 d → 4f emission of Ce3+ in the latter phase is determined by temperature dependence of the photoluminescence decay time. The results show that the onset of the thermal quenching is moved to lower temperatures with increasing gadolinium content. The measurements of temperature dependence of delayed radiative recombination do not reveal a clear evidence that the thermal quenching is caused by thermally induced ionization of the Ce3+ 5d1 excited state. Therefore, the main mechanism responsible for the luminescence quenching is due to the non-radiative relaxation from 5d1 excited state to 4f ground state of Ce3+. The energy transfer processes between Gd3+ and Ce3+ as well as between perovskite and garnet phases are evidenced by the photoluminescence excitation and emission spectra as well as decay kinetic measurements. Thermally stimulated luminescence (TSL) studies in the temperature range 77-497 K and scintillation decays under γ excitation complete the material characterization.

  12. Luminescent and scintillation properties of CsI:Tl films grown by the liquid phase epitaxy method

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu. [Laboratory of Optoelectronic Materials (LOM), Electronics Department of Ivan Franko National University of Lviv, 107 Gen. Tarnawskogo Str., 70017 Lviv (Ukraine); Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Voznyak, T.; Turchak, R. [Laboratory of Optoelectronic Materials (LOM), Electronics Department of Ivan Franko National University of Lviv, 107 Gen. Tarnawskogo Str., 70017 Lviv (Ukraine); Fedorov, A. [Institute for Scintillation Materials of NAS of Ukraine, 60 Lenina Ave., 61001 Kharkiv (Ukraine); Wiesniewski, K.; Grinberg, M. [Institute of Experimental Physics of Gdansk University, 57 Wita Stwoza, 80-952 Gdansk (Poland)

    2010-10-15

    CsI:Tl films have been crystallized by the liquid phase epitaxy (LPE) method from CsI:Tl (0.3 mol.%) crystalline salt onto CsI substrates. The luminescent and scintillation properties of CsI:Tl films are systematically compared with the corresponding properties of CsI:Tl (0.3 and 0.03%) crystals grown from the melt. The luminescence of CsI:Tl films and CsI:Tl (0.03%) crystals in the bands peaked at 2.52 and 2.22 eV is related to the radiative relaxation from the weak-off and strong-off configurations of excitons localized around Tl{sup +} ions, respectively. Apart from single Tl{sup +} centers, in highly doped CsI:Tl (0.3%) crystals creation of Tl{sup +} dimer centers occurs. These centers form the additional emission bands peaked at 2.42 and 1.98 eV related to the weak-off and strong-off configurations of excitons localized around Tl{sup +} dimer centers. We found that the dominant mechanism of excitation of the strong-off luminescence of localized excitons in CsI:Tl films and crystals is the charge-transfer transition between I{sup -} anions and Tl{sup +} ions in single and dimer centers. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  13. A Phosphorescent Iridium(III) Complex-Modified Nanoprobe for Hypoxia Bioimaging Via Time-Resolved Luminescence Microscopy.

    Science.gov (United States)

    Lv, Wen; Yang, Tianshe; Yu, Qi; Zhao, Qiang; Zhang, Kenneth Yin; Liang, Hua; Liu, Shujuan; Li, Fuyou; Huang, Wei

    2015-10-01

    Oxygen plays a crucial role in many biological processes. Accurate monitoring of oxygen level is important for diagnosis and treatment of diseases. Autofluorescence is an unavoidable interference in luminescent bioimaging, so that an amount of research work has been devoted to reducing background autofluorescence. Herein, a phosphorescent iridium(III) complex-modified nanoprobe is developed, which can monitor oxygen concentration and also reduce autofluorescence under both downconversion and upconversion channels. The nanoprobe is designed based on the mesoporous silica coated lanthanide-doped upconversion nanoparticles, which contains oxygen-sensitive iridium(III) complex in the outer silica shell. To image intracellular hypoxia without the interferences of autofluorescence, time-resolved luminescent imaging technology and near-infrared light excitation, both of which can reduce autofluorescence effectively, are adopted in this work. Moreover, gradient O2 concentration can be detected clearly through confocal microscopy luminescence intensity imaging, phosphorescence lifetime imaging microscopy, and time-gated imaging, which is meaningful to oxygen sensing in tissues with nonuniform oxygen distribution.

  14. Influence of surface functionalization on structural and photo-luminescence properties of CeF{sub 3}:Tb nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Anees A., E-mail: aneesaansari@gmail.com

    2017-07-01

    Graphical abstract: We designed highly aqueous dispersible CeF{sub 3}:Tb@LaF{sub 3}@SiO{sub 2} nanoparticles. The epitaxial growth of inert LaF{sub 3} shell and further amorphous silica, respectively, enhanced their optical and luminescence properties, which is highly usable for luminescent biolabeling, and optical bio-probe etc. - Abstract: Highly luminescent and aqueous soluble CeF{sub 3}:Tb (core),CeF{sub 3}:Tb@LaF{sub 3}(core/shell) and CeF{sub 3}:Tb@LaF{sub 3}@ SiO{sub 2} (core/shell/Si) nanoparticles(NPs) with mean particle size 12 nm were prepared by co-precipitation method at low temperature. X-ray diffraction pattern verified the phase purity, high crystallinity of hexagonal structure. The TEM image and SAED pattern revealed the single phase polycrystalline nature, well-dispersed irregular shaped hexagonal structure. FTIR spectra show the characteristic infrared peaks of silica, it suggests the successful silica surface coating around the core/shell NPs. The excitation and emission intensity of core/shell NPs were remarkably increased then their counterpart core NPs. It implies that a significant amount of nonradiative transition centers existing on the surface of core NPs has been eliminated due to the formation of passivated LaF{sub 3} layer. The silica surface modification over the core/shell NPs strikingly enhanced the solubility character in an aqueous environment.

  15. Microprobe analysis, iono- and photo-luminescence of Mn2+ activated ZnGa2O4 fibres

    Science.gov (United States)

    Santos, N. F.; Fernandes, A. J. S.; Alves, L. C.; Sobolev, N. A.; Alves, E.; Lorenz, K.; Costa, F. M.; Monteiro, T.

    2013-07-01

    Cubic ZnGa2O4 fibres have been grown by the laser floating zone technique with different pulling rates. In fibres activated with manganese ions, the room temperature photo- and iono-luminescence is dominated by an intense green emission which is observed by the naked eye. The green band is due to an overlap of the 4T1 → 6A1 intraionic transitions of the Mn2+ ions in different sites in the gallate host. The fibres' photoluminescence spectra have been found to be dependent on the excitation energy. Additionally, the intensity of the green photo- and iono-luminescence is strongly sensitive to the measurement temperature and proton irradiation time. Micro PIXE analysis was used in order to verify the homogeneous distribution of the Mn luminescence activators and determine its concentration as well as for verification of impurity contents that may have been incorporated during the fibres growth. The potential of ionoluminescence measurements for characterization of optical materials is discussed.

  16. On the origin of stretched exponential (Kohlrausch) relaxation kinetics in the room temperature luminescence decay of colloidal quantum dots.

    Science.gov (United States)

    Bodunov, E N; Antonov, Yu A; Simões Gamboa, A L

    2017-03-21

    The non-exponential room temperature luminescence decay of colloidal quantum dots is often well described by a stretched exponential function. However, the physical meaning of the parameters of the function is not clear in the majority of cases reported in the literature. In this work, the room temperature stretched exponential luminescence decay of colloidal quantum dots is investigated theoretically in an attempt to identify the underlying physical mechanisms associated with the parameters of the function. Three classes of non-radiative transition processes between the excited and ground states of colloidal quantum dots are discussed: long-range resonance energy transfer, multiphonon relaxation, and contact quenching without diffusion. It is shown that multiphonon relaxation cannot explain a stretched exponential functional form of the luminescence decay while such dynamics of relaxation can be understood in terms of long-range resonance energy transfer to acceptors (molecules, quantum dots, or anharmonic molecular vibrations) in the environment of the quantum dots acting as energy-donors or by contact quenching by acceptors (surface traps or molecules) distributed statistically on the surface of the quantum dots. These non-radiative transition processes are assigned to different ranges of the stretching parameter β.

  17. Luminescence features from conical bubble collapse in 1,2 propanediol and its perturbation adding sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete, M; Godinez, F A [Universidad Nacional Autonoma de Mexico, Ciudad Universitaria No. 3000, Col. Copilco Universidad, Delegacion de Coyoacan, Mexico, D. F. Codigo Postal 04360, Instituto de Ingenieria, Lab. de Fotofisica (Mexico); Sanchez, C [Universidad Nacional Autonoma de Mexico, Ciudad Universitaria No. 3000, Col. Copilco Universidad, Delegacion de Coyoacan, Mexico, D. F. Codigo Postal 04360, Lab. de Fotonica y Microondas (Mexico); Mejia, E V; Villagran, M, E-mail: mnm@pumas.iingen.unam.mx [Universidad Nacional Autonoma de Mexico, Ciudad Universitaria No. 3000, Col. Copilco Universidad, Delegacion de Coyoacan, Mexico, D. F. Codigo Postal 04360 (Mexico)

    2011-01-01

    A summary of experimental findings on the luminescence from bubble collapse, CBL, varying the gas inert bubble content, the driving pressure and perturbing the liquid piston with small quantities of sulfuric acid is presented. The temporal, spectral, and spatial characteristics of the luminescence regarding with dynamic features of collapse are also examinees. CBL was reproduced using Argon gas, and 1, 2-propanediol as liquid piston. In general, the pulse shape exhibits a large variety of profiles. The luminescence intensity was increased two-fold and the pulse width decreased almost to half when the liquid was disturbed with sulfuric acid. Spectrally, the Swan, CH and CN lines were observed at low volume of Ar gas and low driving pressure, lines of OH{sup 0}, Na*, K* always appear superimposed on an underlying continuum background. De-excitation of sodium atom at 589 nm and two satellites diffuse bands at {approx}554 nm and {approx}620 nm from alkali-metal-argon exciplexes was observed in both systems under certain conditions. All these findings point towards several sources of light emission that are generated during the compression time line, resulting in temporally and spatially inhomogeneous pulse. A mechanism for explain the bright CBL is broached.

  18. Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

    Energy Technology Data Exchange (ETDEWEB)

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E.; Derenzo,Stephen E.

    2007-01-18

    Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependence of BGO, X-ray excited luminescence intensities ofall three phases remain relatively constant throughout the temperaturerange 10 - 295 K. This result indicates that the Sillen phases undergoless thermal quenching than BGO. The low temperature and room temperatureradio-luminescence decay times were determined from pulsed x-raymeasurements. At room temperature, SrBiO2Cl exhibits faster decays thanBGO, while, BaBiO2Cl and BaBiO2Br have decay times similar toBGO.

  19. Intense up-conversion luminescence in Er3+/Yb3+ co-doped CeO2 powders

    Science.gov (United States)

    Singh, Vijay; Rathaiah, M.; Venkatramu, V.; Haase, Markus; Kim, S. H.

    2014-03-01

    The Er3+ and Er3+/Yb3+ co-doped CeO2 powders have been prepared by a urea combustion route. The structural, morphological, compositional and vibrational analysis of the Er3+:CeO2 and Er3+/Yb3+:CeO2 powders have been studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy. The optical and luminescence properties of Er3+:CeO2 and Er3+/Yb3+:CeO2 powders have been studied by using laser excited spectroscopy. The effects of Yb3+ doping on up-conversion luminescence of Er3+ co-doped CeO2 powders were studied. The ratio of red to green intensity is decreased in Er3+:CeO2 whereas the ratio is increased in Er3+/Yb3+:CeO2 powders with increase of power. The effect of co-doping with the Yb3+ ions on the visible luminescence of Er3+ and the energy transfer mechanism responsible for the variation in the green and red intensity are discussed. The results indicate that these materials may be suitable for display and light emitting devices.

  20. Molecular Tectonics: Design of Enantiopure Luminescent Heterometallic Ir(III)-Cd(II) Coordination Network.

    Science.gov (United States)

    Xu, Chaojie; Guenet, Aurélie; Kyritsakas, Nathalie; Planeix, Jean-Marc; Hosseini, Mir Wais

    2015-11-02

    With the aim of combining luminescence and chirality in heterometallic Ir(III)-Cd(II) coordination networks, synthetic strategies for the formation of new Ir(III)-based chiral metallatectons ([Ir(dFppy)2(1)][PF6]), both as a racemic mixture of Δ and Λ enantiomers (rac-[Ir(dFppy)2(1)][PF6]) and as enantiopure complexes (Δ-[Ir(dFppy)2(1)][PF6] and Λ-[Ir(dFppy)2(1)][PF6]), were developed. The final compounds were characterized both in solution and in the crystalline phase. Notably, their crystal structures were determined by single crystal X-ray diffraction, and their photophysical properties in solution and in the solid state were investigated. Combination of the cationic linear metallatecton with Cd(2+) iodide salt ([CdI3](-)), behaving as an anionic two-connecting node, leads to the formation of 1D chiral and neutral heterometallic Ir(III)-Cd(II) luminescent coordination networks both as a racemic mixture and as enantiomerically pure infinite architectures. The latter have been structurally studied in the solid state by X-ray diffraction both on single crystals and on microcrystalline powders. The infinite coordination networks display phosphorescence in the solid state at ca. 600 nm upon excitation at 400 nm.

  1. Heterogeneously Nd(3+) doped single nanoparticles for NIR-induced heat conversion, luminescence, and thermometry.

    Science.gov (United States)

    Marciniak, Lukasz; Pilch, Aleksandra; Arabasz, Sebastian; Jin, Dayong; Bednarkiewicz, Artur

    2017-06-22

    The current frontier in nanomaterials engineering is to intentionally design and fabricate heterogeneous nanoparticles with desirable morphology and composition, and to integrate multiple functionalities through highly controlled epitaxial growth. Here we show that heterogeneous doping of Nd(3+) ions following a core-shell design already allows three optical functions, namely efficient (η > 72%) light-to-heat conversion, bright NIR emission, and sensitive (SR > 0.1% K(-1)) localized temperature quantification, to be built within a single ca. 25 nm nanoparticle. Importantly, all these optical functions operate within the transparent biological window of the NIR spectral region (λexc ∼ 800 nm, λemi ∼ 860 nm), in which light scattering and absorption by tissues and water are minimal. We find NaNdF4 as a core is efficient in absorbing and converting 808 nm light to heat, while NaYF4:1%Nd(3+) as a shell is a temperature sensor based on the ratio-metric luminescence reading but an intermediate inert spacer shell, e.g. NaYF4, is necessary to insulate the heat convertor and thermometer by preventing the possible Nd-Nd energy relaxation. Moreover, we notice that while temperature sensitivity and luminescence intensity are optically stable, increased excitation intensity to generate heat above room temperature may saturate the sensing capacity of temperature feedback. We therefore propose a dual beam photoexcitation scheme as a solution for possible light-induced hyperthermia treatment.

  2. Determination of veterinary penicillin antibiotics by fast high-resolution liquid chromatography and luminescence detection.

    Science.gov (United States)

    Castillo-García, M L; Aguilar-Caballos, M P; Gómez-Hens, A

    2017-08-01

    A chromatographic method based on the use of a fused-core column and luminescence detection is described for the determination of six penicillin antibiotics used in veterinary practice, namely amoxicillin, ampicillin, penicillin G, oxacillin, cloxacillin and nafcillin. The use of this column provides the separation of these antibiotics with retention times lower than 4.5min. The tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)] - Ce(IV) system has been used as post-column derivatization reagent, obtaining a luminescence signal (λem 610nm) proportional to the analyte concentration when the system is excited at 450nm. The dynamic ranges of the calibration graphs are 100-10,000ngmL(-1) for all the antibiotics assayed and the limits of detection are in the range of 44-51ngmL(-1). The precision, established at two concentration levels of each analyte and expressed as the percentage of the relative standard deviation is in the range of 6.9-9.8%. The method has been satisfactorily applied to the analysis of water and pharmaceutical samples, with recoveries ranging from 88.6% to 108.5%. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Regularities of intermittent luminescence from spherical and tetrapod-shaped quantum dots

    CERN Document Server

    Vitukhnovsky, A G; Lidsky, V V; Khokhlov, E M

    2011-01-01

    Intermittent photoluminescence of colloidal core/shell semiconductor nanocrystals of spherical and branched shape was studied under CW-laser excitation. Luminescent multichannel registration system was applied for the fluorescence detection of single quantum dots (QDs) in the polystyrene matrix. Comparative statistical data were obtained and analyzed for nano-sphere CdSe/CdS and nano-tetrapod CdTe/CdSe crystals. It was found that "on-" and "off-" blinking times are distributed according to the power law both for spherical CdSe/CdS and tetrapod shape CdTe/CdSe samples in spite of significant QD formfactor differences. We have also found that regardless of the QD-shape both successive "on"-times and successive "off "-times are correlated and pointing out to the memory effect in the mechanism of QD re-emission comprising the prehistory of exciton birth and recombination. Pearson-s co-efficients were calculated for the correlations of QD-luminescence behavior. Results of experimental measurements were compared wi...

  4. Polysiloxane-based luminescent elastomers prepared by thiol-ene "click" chemistry.

    Science.gov (United States)

    Zuo, Yujing; Lu, Haifeng; Xue, Lei; Wang, Xianming; Wu, Lianfeng; Feng, Shengyu

    2014-09-26

    Side-chain vinyl poly(dimethylsiloxane) has been modified with mercaptopropionic acid, methyl 3-mercaptopropionate, and mercaptosuccinic acid. Coordinative bonding of Eu(III) to the functionalized polysiloxanes was then carried out and crosslinked silicone elastomers were prepared by thiol-ene curing reactions of these composites. All these europium complexes could be cast to form transparent, uniform, thin elastomers with good flexibility and thermal stability. The networks were characterized by FTIR, NMR, UV/Vis, and luminescence spectroscopy as well as by scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The europium elastomer luminophores exhibited intense red light at 617 nm under UV excitation at room temperature due to the (5)D0 →(7)F2 transition in Eu(III) ions. The newly synthesized luminescent materials offer many advantages, including the desired mechanical flexibility. They cannot be dissolved or fused, and so they have potential for use in optical and electronic applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Persistently luminescent and photocatalytic properties of ZnGa2O4 phosphors

    Science.gov (United States)

    Li, Darong; Wang, Yinhai; Xu, Ke; Li, Lei; Hu, Zhengfa

    2015-04-01

    The phosphors ZnGa2O4 were synthesized via high temperature solid-state reaction. The crystal structure, photoluminescence, persistent luminescence, and photocatalytic properties of ZnGa2O4 were studied in detail. The x-ray diffraction patterns showed that some remaining phases of ZnO and β-Ga2O3 appeared with the excess amount of ZnO and Ga2O3, respectively. The results of the Raman spectra indicated that the first order Raman active modes of ZnGa2O4 were attributed to O2- ions and Zn2+ ions in tetrahedral sites. The phosphors exhibited a broad-band emission around 430 nm, which could be ascribed to the Ga-O transition of regular octahedral sites in the spinel lattice of ZnGa2O4. It also exhibited the emission peak around 430 nm shift to longer wavelength with the amount of the excess ZnO. The persistent luminescence of ZnGa2O4 could be observed for 10 min by naked eyes at room temperature under 254 nm ultraviolet (UV) excitation. In addition, photocatalytic activity test showed that ZnGa2O4 exhibited excellent photocatalytic activity for the degradation of Rhodamine B by the UV irradiation. It was indicated that the traps played an important role in trapping the electrons or holes to decrease the combination of the holes or electrons producing by the irradiation.

  6. Fabrication and luminescent properties of highly transparent Er3Al5O12 ceramics

    Science.gov (United States)

    Hu, Song; Qin, Xianpeng; Liu, Xiaoxia; Zhou, Guohong; Lu, Chunhua; Wang, Shiwei; Xu, Zhongzi

    2017-09-01

    Highly transparent Er3Al5O12 (ErAG) ceramic was fabricated by a solid-state reactive sintering method under vacuum. The optical property, microstructure and up-conversion luminescence of the ErAG ceramic were investigated. For the 3 mm thick sample, the in-line transmittance at the wavelength of 3000 nm and 425 nm were about 84% and 81%, respectively, which was very close to the theoretical transmittance of the Er3Al5O12 single crystal. Micrograph of the ErAG transparent ceramic exhibited a pore-free structure and the density of the ceramic was measured to be 6.38 g/cm3. Average grain size of the ceramic was about 9 μm. When pumped by a 980 nm laser diodes (LD), strong green and red emission in the ErAG ceramic was observed from the photoluminescence (PL) spectrum. The luminescent properties of the ceramic under the excitation of LD with various pumping power were investigated.

  7. FORMATION OF LUMINESCENT OPTICAL WAVEGUIDES IN SILICATE GLASS MATRIX BY THE ION-EXCHANGE TECHNIQUE

    Directory of Open Access Journals (Sweden)

    I. A. Dyomichev

    2015-01-01

    Full Text Available We present spectra of the alkali-silicate glasses with copper ions in near-surface area, introduced by ion exchange of different temperature and duration. It is shown that the reduction of Cu2+ in the near-surface area causes existence of Cu+ and neutral atoms in glass after the ion-exchange in divalent salt. The ion-exchange itself involves only Cu+ and Na+ ions. The formation of subnanometer clusters Cun is due to neutral copper atoms staying in near-surface zone. We have shown that the waveguide layer in near-surface area, made by ion-exchange, has а visible luminescence with the excitation by UVradiation. At the same time, the contribution to luminescence is made by Cu+ ions, molecular clusters Cun and by dimers Cu+ - Cu+ . During the high-temperature ion-exchange at 600 °С the formation and destruction equilibrium shift of molecular clusters Cun can be seen. An hour ion-exchange leads to molecular clusters Cun destruction, while at time periods less than 30 min and around 18 hours it leads to the formation of Cun. The sample turns green after 18,5 hours ion-exchange showing formation of a considerable amount of divalent copper ions Cu2+ therein.

  8. Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

    Energy Technology Data Exchange (ETDEWEB)

    Page, R.H.; Schaffers, K.I.; Waide, P.A.; Tassano, J.B.; Payne, S.A.; Kruplce, W.F.; Bischel, W.K. [Gemfire Corporation, Palo Alto, CA (United States)

    1997-07-26

    We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beam profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.

  9. Optical and luminescence properties of Dy3+ doped sodium silicate glass

    Science.gov (United States)

    Srisittipokakun, N.; Kaewkhao, J.

    2017-07-01

    The aim of the present work is to study the optical and luminescence properties of Dy2O3 doped Na2O-BaO-Bi2O3-SiO2 glasses. The Dy3+ ion is chosen as dopant because it emits three visible bands, blue (470-485 nm; 4F9/2→6H15/2), yellow (570-580 nm; 4F9/2→6H13/2) and red (640-655 nm; 4F9/2→6H11/2) luminescence and finds its applications in the fields of laser, white LEDs, telecommunication technology and display devices. NaBaBiSiDy glasses with the compositions of (30-x)SiO2: 10Bi2O3: 30Na2O: 30BaO: xDy2O3 where x=0.0, 0.1, 0.5, 1.0, 1.5 and 2.0 mol% were prepared by melt-quenching technique and characterized by using density, optical absorption photoluminescence (PL) and decay rate measurements as function of different concentrations. The density (ρ), molar volume (VM) and refractive index obtained were found to increase with increase in the concentration of Dy2O3 in the glass matrix. The chromaticity coordinates were calculated from emission spectra and analyzed with CIE color diagram and appear in the white light region under ultraviolet excitation.

  10. submitter Preparation and luminescence properties of ZnO:Ga – polystyrene composite scintillator

    CERN Document Server

    Burešová, Hana; Turtos, Rosana Martinez; Jarý, Vítězslav; Mihóková, Eva; Beitlerová, Alena; Pjatkan, Radek; Gundacker, Stefan; Auffray, Etiennette; Lecoq, Paul; Nikl, Martin; Čuba, Václav

    2016-01-01

    Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-...

  11. Identification of Lanthanide(III) Luminophores in Magnetic Circularly Polarized Luminescence Using Raman Optical Activity Instrumentation.

    Science.gov (United States)

    Wu, Tao; Kapitán, Josef; Andrushchenko, Valery; Bouř, Petr

    2017-05-02

    Luminescence of lanthanide(III) ions sensitively reflects atomic environment. However, the signal may be weak and covered by Raman scattering. In the present study magnetic circularly polarized luminescence (MCPL) is explored as a more sensitive tool to recognize the lanthanide signal and assign underlying electronic transitions. MCPL spectra of the Na3[Ln(DPA)3] (Ln = Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Er) complexes were recorded on a Raman optical activity (ROA) instrument. The ROA spectrometer equipped with the 532 nm laser excitation sensitively detects differences in scattering of left- and right-circularly polarized light caused by the magnetic field. Weak bands sometimes invisible in unpolarized measurement could be detected as MCPL. Observed transitions were assigned with the aid of the ligand-field theory. MCPL also reflects the environment: chloride and nitrate salts (LnCl3 and Ln(NO3)3) provide a different signal than the complex; for Nd(III) the signal responds to distribution of chloride and nitrate ions around the metal. The MCPL technique thus appears useful for identification and assignment of lanthanide transitions and increases the potential of fluorescent probes for applications in analytical chemistry and imaging.

  12. Structural and luminescence study of antimony-zinc borophosphate glass doped with iron

    Science.gov (United States)

    Pang, Xie Guan; Eeu, Tien Yew; Leow, Ting Qiao; Shamsuri, Wan Nurulhuda Wan; Hussin, Rosli

    2013-05-01

    Antimony zinc borophosphate glass were prepared with the composition of 20ZnO-30B2O3-xP2O5-(50-x)Sb2O3-2Fe2O3 (0≤x≤50 mol%) using the melt quenching method. The starting materials were mixed and preheat for 30 minutes and transfer into high temperature furnace for melting. The structure of samples were measured using Fourier-Transform Infrared (FT-IR) Spectroscopy. The spectra showed that network structure in the samples are mainly based on P=O, PO2, P-O, B-O-B and B-O units. With increasing P2O5 content, the vibration of P-O tends to shift towards lower wavenumber. Meanwhile, the luminescence was studied using Photoluminescence (PL) Spectroscopy. The samples were excited at specific wavelengths (265 - 300 nm). The emission profiles were obtained to study the energy transfer process. Luminescence of violet colour from samples were also recorded to correlate with PL results.

  13. A solid-state dedicated circularly polarized luminescence spectrophotometer: Development and application.

    Science.gov (United States)

    Harada, Takunori; Hayakawa, Hiroshi; Watanabe, Masayuki; Takamoto, Makoto

    2016-07-01

    A new solid-state dedicated circularly polarized luminescence (CPL) instrument (CPL-200CD) was successfully developed for measuring true CPL spectra for optically anisotropic samples on the basis of the Stokes-Mueller matrix approach. Electric components newly installed in the CPL-200CD include a pulse motor-driven sample rotation holder and a 100 kHz lock-in amplifier to achieve the linearly polarized luminescence measurement, which is essential for obtaining the true CPL signal for optically anisotropic samples. An acquisition approach devised for solid-state CPL analysis reduces the measurement times for a data set by ca. 98% compared with the time required in our previous method. As a result, the developed approach is very effective for samples susceptible to light-induced degradation. The theory and implementation of the method are described, and examples of its application to a CPL sample with macroscopic anisotropies are provided. An important advantage of the developed instrument is its ability to obtain molecular information for both excited and ground states because circular dichroism measurements can be performed by switching the monochromatic light to white light without rearrangement of the sample.

  14. Microwave synthesis of homogeneous and highly luminescent BCNO nanoparticles for the light emitting polymer materials

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, Hideharu [Battery Materials Laboratory, Kurashiki Research Center, Kuraray Co., Ltd., 2045-1, Sakazu, Kurashiki, Okayama 710-0801 (Japan); Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan); Ogi, Takashi, E-mail: ogit@hiroshima-u.ac.jp [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan); Iskandar, Ferry [Department of Physics, Institute of Technology Bandung, Ganesha 10, Bandung 40132, West Java (Indonesia); Aishima, Kana; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan)

    2015-10-15

    Nano-sized boron carbon oxynitride (BCNO) phosphors around 50 nm containing no rare earth metal and free from color heterogeneity were synthesized from mixtures of boric acid, urea, and citric acid by microwave heating with substantially shorter reaction times and lower temperatures than in the conventional BCNO preparation method such as electric-furnace heating. The emission wavelength of the phosphors varied with the mixing ratio of raw materials and it was found that lowering the proportion of urea to boric acid or citric acid tended to increase the internal quantum yield and shorten the emission wavelength under excitation at 365 nm. It was also found for the first time that a light-emitting polymer could be synthesized from a mixture of the prepared BCNO nanoparticles and a polyvinyl alcohol. This polymer composite exhibited uniform dispersion and stabilization of the luminescence and had a high internal quantum yield of 54%, which was higher than that of the phosphor alone. - Highlights: • Nano-sized BCNO phosphor was synthesized via microwave heating. • BCNO nanophosphor has homogeneous and high luminescence. • Emission wavelength was tunable by changing the ratio of precursor components. • BCNO nanophosphor can be easily dispersed in a polyvinyl alcohol. • BCNO–polymer composite exhibited uniform high internal quantum yield.

  15. High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings.

    Science.gov (United States)

    Benseman, Timothy M; Hao, Yang; Vlasko-Vlasov, Vitalii K; Welp, Ulrich; Koshelev, Alexei E; Kwok, Wai-Kwong; Divan, Ralu; Keiser, Courtney; Watanabe, Chiharu; Kadowaki, Kazuo

    2017-04-16

    Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

  16. Visible-light sensitized luminescent europium(III)-β-diketonate complexes: bioprobes for cellular imaging.

    Science.gov (United States)

    Reddy, M L P; Divya, V; Pavithran, Rani

    2013-11-21

    Visible-light sensitized luminescent europium(III) molecular materials are of considerable importance because their outstanding photophysical properties make them well suited as labels in fluorescence-based bioassays and low-voltage driven pure red-emitters in optoelectronic technology. One challenge in this field is development of visible-light sensitizing ligands that can form highly emissive europium(III) complexes with sufficient stability and aqueous solubility for practical applications. Indeed, some of the recent reports have demonstrated that the excitation-window can be shifted to longer-wavelengths in europium(III)-β-diketonate complexes by appropriate molecular engineering and suitably expanded π-conjugation in the complex molecules. In this review, attention is focused on the latest innovations in the syntheses and photophysical properties of visible-light sensitized europium(III)-β-diketonate complexes and their application as bioprobes for cellular imaging. Furthermore, luminescent nanomaterials derived from long-wavelength sensitized europium(III)-β-diketonate complexes and their application in life sciences are also highlighted.

  17. Synthesis of Luminescent Graphene Quantum Dots with High Quantum Yield and Their Toxicity Study.

    Directory of Open Access Journals (Sweden)

    Dan Jiang

    Full Text Available High fluorescence quantum yield graphene quantum dots (GQDs have showed up as a new generation for bioimaging. In this work, luminescent GQDs were prepared by an ameliorative photo-Fenton reaction and a subsequent hydrothermal process using graphene oxide sheets as the precursor. The as-prepared GQDs were nanomaterials with size ranging from 2.3 to 6.4 nm and emitted intense green luminescence in water. The fluorescence quantum yield was as high as 24.6% (excited at 340 nm and the fluorescence was strongest at pH 7. Moreover, the influences of low-concentration (12.5, 25 μg/mL GQDs on the morphology, viability, membrane integrity, internal cellular reactive oxygen species level and mortality of HeLa cells were relatively weak, and the in vitro imaging demonstrated GQDs were mainly in the cytoplasm region. More strikingly, zebrafish embryos were co-cultured with GQDs for in vivo imaging, and the results of heart rate test showed the intake of small amounts of GQDs brought little harm to the cardiovascular of zebrafish. GQDs with high quantum yield and strong photoluminescence show good biocompatibility, thus they show good promising for cell imaging, biolabeling and other biomedical applications.

  18. Synthesis of Luminescent Graphene Quantum Dots with High Quantum Yield and Their Toxicity Study

    Science.gov (United States)

    Jiang, Dan; Chen, Yunping; Li, Na; Li, Wen; Wang, Zhenguo; Zhu, Jingli; Zhang, Hong; Liu, Bin; Xu, Shan

    2015-01-01

    High fluorescence quantum yield graphene quantum dots (GQDs) have showed up as a new generation for bioimaging. In this work, luminescent GQDs were prepared by an ameliorative photo-Fenton reaction and a subsequent hydrothermal process using graphene oxide sheets as the precursor. The as-prepared GQDs were nanomaterials with size ranging from 2.3 to 6.4 nm and emitted intense green luminescence in water. The fluorescence quantum yield was as high as 24.6% (excited at 340 nm) and the fluorescence was strongest at pH 7. Moreover, the influences of low-concentration (12.5, 25 μg/mL) GQDs on the morphology, viability, membrane integrity, internal cellular reactive oxygen species level and mortality of HeLa cells were relatively weak, and the in vitro imaging demonstrated GQDs were mainly in the cytoplasm region. More strikingly, zebrafish embryos were co-cultured with GQDs for in vivo imaging, and the results of heart rate test showed the intake of small amounts of GQDs brought little harm to the cardiovascular of zebrafish. GQDs with high quantum yield and strong photoluminescence show good biocompatibility, thus they show good promising for cell imaging, biolabeling and other biomedical applications. PMID:26709828

  19. Luminescence optically stimulated: theory and applications; Luminiscencia opticamente estimulada: teoria y aplicaciones

    Energy Technology Data Exchange (ETDEWEB)

    Rivera M, T.; Azorin N, J. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, 09340 Mexico D.F. (Mexico)

    2002-07-01

    The thermally stimulated luminescence (Tl) has occupied an important place in the Solid state physics (FES) by the flexibility of the phenomena, mainly for its applications in the fields of Radiation Physics (FR) and Medical Physics (MF). The reason of this phenomena lies in the fact of the electrons release by the action of heat. Under that same reason, it can be used the action of another stimulant agent for releasing the trapped electrons in the metastable states (EM), this agent is the light which has the same effect that the heat, giving as result the production of light photons at using light in the visible spectra, of different wavelength that the excitation light. This phenomena is called Luminescence optically stimulated (LOE). The LOE has a great impact in the Solid State Physics (FES), dating and now in the use of the phenomena as a dosimetric method, alternate to the Tl, for its use in the ionizing and non-ionizing radiations fields. (Author)

  20. Near-infrared-light mediated ratiometric luminescent sensor for multimode visualized assays of explosives.

    Science.gov (United States)

    Hu, Xiaoxia; Wei, Ting; Wang, Jie; Liu, Zi-En; Li, Xinyang; Zhang, Binhao; Li, Zhihao; Li, Lele; Yuan, Quan

    2014-10-21

    The development of a portable and easy-to-use device for the detection of explosives with high sensitivity and selectivity is in high demand for homeland security and public safety. In this study, we demonstrate miniaturized devices depending on the upconversion ratiometric luminescent probe for point-of-care (POC) assay of explosives with the naked-eye. When the PEI-coated upconversion nanoparticles (UCNPs) selectively bonded to 2,4,6-trinitrotoluene (TNT) explosives by the formation of Meisenheimer complex, the formed of UCNP-Meisenheimer complexes show turned visible multicolor upconversion luminescence (UCL) on account of TNT-modulating Förster resonance energy transfer process under near-infrared excitation. With UCL emission at 808 nm as internal standard and ratiometric UCL at 477 nm to that at 808 nm (I477/I808) as output signal, the probe can simultaneously meet the accuracy for TNT explosives quantitative analysis. In addition, this easy-to-use visual technique provides a powerful tool for convenient POC assay of rapid explosives identification.

  1. The luminescence profile of carbon dots synthesized from α-cellulose under different acid hydrolysis conditions

    Science.gov (United States)

    Ng, Yann Huey; Chin, Suk Fun; Pang, Suh Cem; Ng, Sing Muk

    2017-08-01

    This work reports the study on the luminescence properties portrayed by carbon dots synthesized under different acid hydrolysis conditions. Sulphuric acid was employed to dehydrate and carbonize α-cellulose as starting precursor. We revealed that the emissions of carbon dots were strongly dependent on the reaction condition during the synthesis, which include hydrolysis time and temperature. Initial mild acid hydrolysis at 4 °C and followed by incubation at room temperature was found favourable to the production of carbon dots emitting green fluorescence, whereas higher temperatures of 50 and 70 °C would produce carbon dots emitting blue fluorescence. At fixed temperature of 50 °C, prolonged synthesis time could shift the emission of carbon dots from green to blue. The green emission was recorded to have a peak at 500 nm when excited at 450 nm; whereas the highest intensity for the blue emission was recorded at 456 nm when excited at 357 nm. Both as-synthesized carbon dots showed excitation-independent emission. The quantum yields for the green and blue carbon dots were evaluated to be 6.4% and 4.0% respectively. The carbon dots emitting blue emission was of better photostability as compared to the carbon dots emitting green fluorescence. Both types of carbon dots synthesized in this study showed significant pH-dependent trend with higher intensity at lower pH condition.

  2. Subsurface excitations in a metal

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Sosolik, C. E.

    2009-01-01

    We investigate internal hot carrier excitations in a Au thin film bombarded by hyperthermal and low energy alkali and noble gas ions. Excitations within the thin film of a metal-oxide-semiconductor device are measured revealing that ions whose velocities fall below the classical threshold given...... by the free-electron model of a metal still excite hot carriers. Excellent agreement between these results and a nonadiabatic model that accounts for the time-varying ion-surface interaction indicates that the measured excitations are due to semilocalized electrons near the metal surface....

  3. Excitation mechanism of Er{sup 3+} in a-Si:H; Anregungsmechanismus von Er{sup 3+} in a-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Kuehne, H.

    2004-07-01

    The aim of this work is the examination of the optoelectronical material a-Si:H (Er). It is characterised in the good electronic properties of the a-Si:H and the emission wavelength of 1.5 micrometer of erbium which coincides with the absorbtion minimum of glasfibres. Photoluminescence measurements confirm the assumption that oxigen is necessary for the optical activation of Er{sup 3+} in addition to the symmetrical breaking of the crystal field. The flexible lattice of a-Si:H enables a high concentration of Erbium up to 5.10{sup 21}/cm{sup 3} with a quantum efficiency of the luminescence of 0.5-1.5.10{sup -4} at room temperature. Photoluminescence excitation and absorption measurements of a-Si:H (Er) show, that there is no direct excitation of the erbium ions because the absorption of the Er{sup 3+} ions is two orders of magnitude below the absorption of silicon. The excitation or the Er{sup 3+} ions takes place through the absorption in silicon with additional energy transfer to Erbium. Photoluminescence measurements are done in order to differentiate between the possible excitation channels, the intrinsic bond-bond channel and the excitation through defects. The different temperature dependence of the intensity of the intrinsic luminescence (77 K - 300 K >3 orders of magnitude) in comparison with the defect luminescence and the Erbium luminescence (both 1-1.5 orders of magnitude) shows that the energy transfer takes place over defects. Luminescence and absorption measurements with boron doped a-Si:H (Er) show no dependence of the Erbium luminescence in dependence of defect density or the electrical charge of the defects. The luminescence spectra show a break in the defect luminescence at 0.84 eV. This agrees with the first excited state of the Er{sup 3+} ion combined with a clearly smaller line width of the defect luminescence (0.18 eV in comparision with >0.3 eV in erbium free a-Si:H). This result shows the resonance of the energy transfer. The resonance is

  4. Luminescent properties of ZrO2:Tb nanoparticles for applications in neuroscience

    Science.gov (United States)

    Słońska, A.; Kaszewski, J.; Wolska-Kornio, E.; Witkowski, B.; Wachnicki, Ł.; Mijowska, E.; Karakitsou, V.; Gajewski, Z.; Godlewski, M.; Godlewski, M. M.

    2016-09-01

    In this paper a new generation of non-toxic nanoparticles based on the zirconium oxide doped with 0.5%Tb and co-doped by the range of 0-70% with Y was evaluated for the use as a fluorescent biomarker of neuronal trafficking. The ZrO2:Tb nanoparticles were created by microwave driven hydrothermal method. Influence of the yttrium content and thermal processing on the Tb3+ related luminescence emission was discussed. The higher intensities were achieved, when host was cubic and for the nanoparticles with 33 nm. Presence of yttrium was associated with the energy coupling of the host and dopant, wide excitation band is present at 309 and 322 nm before and after calcination respectively.

  5. [The Development of Luminescent Nano-probes on Hard X-ray Irradiation].

    Science.gov (United States)

    Osakada, Yasuko

    2016-01-01

      X-rays are widely used in imaging applications such as diffraction imaging of crystals and medical imaging. In particular, X-ray computed tomography (CT) is a critical tool for clinical and disease diagnostics. The principle of conventional CT is based on X-ray attenuation caused by photoelectric absorption and scattering. In addition to conventional CT, a number of novel methodologies are presently under development, including state-of-the-art instrument technologies and chemical probes to fulfill diagnosis criteria. Among these novel methodologies, we have utilized hard X-ray-excited optical luminescence (hXEOL) as a new methodology to enhance the contrast of the image. Herein, we explored the possibility of hXEOL via iridium-doped polymer nanoparticles and biomolecule-directed metal clusters and propose it as a potential platform for new X-ray imaging.

  6. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand.

    Science.gov (United States)

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-25

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Non-blinking and photostable upconverted luminescence from single lanthanide-doped nanocrystals

    Science.gov (United States)

    Wu, Shiwei; Han, Gang; Milliron, Delia; Aloni, Shaul; Altoe, Virginia; Talapin, Dmitri; Cohen, Bruce; Schuck, Jim

    2010-03-01

    The development of probes for single-molecule imaging has dramatically facilitated the study of individual molecules in cells and other complex environments. Single-molecule probes ideally exhibit good brightness, uninterrupted emission, resistance to photobleaching, and minimal spectral overlap with cellular autofluorescence. However, most single-molecule probes are imperfect in several of these aspects, and none have been shown to possess all of these characteristics. In this talk, I will show that individual lanthanide-doped upconverting nanoparticles (UCNPs) emit non-blinking and photostable near-infrared to visible upconverted luminescence when excited by a 980-nm continuous wave laser, suggesting that UCNPs are ideally suited for single-molecule imaging experiments.

  8. Tunable upconversion luminescence of monodisperse Y2O3: Er3+/Yb3+/Tm3+ nanoparticles

    Science.gov (United States)

    Wu, Qibai; Lin, Shaoteng; Xie, Zhongxiang; Zhang, Liqing; Qian, Yannan; Wang, Yaodong; Zhang, Haiyan

    2017-12-01

    Monodisperse Y2O3: Er3+/Yb3+/Tm3+ nanoparticles with various dopant concentrations have been synthesized successfully by a homogeneous precipitation method. Their phase structures and surface morphologies have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diversities of upconversion luminescence spectra and CIE coordinates of prepared samples are investigated in detail at room temperature under 980 nm excitation. Through adjusting the concentrations of Yb3+, Tm3+ and Er3+ ions, three upconversion emission bands in red, green and blue region could be tunable to achieve the color of interest and near white light emission can be obtained in the tri-doped Y2O3 nanoparticles for a variety of application.

  9. Controlling the yellow luminescence intensity from n-GaN during cathodoluminescence

    Science.gov (United States)

    Dhamodaran, S.

    2011-01-01

    GaN grown on sapphire by hydride vapour phase epitaxy is probed by ion channeling, Raman and cathodoluminescence (CL) spectroscopy. Channeling and Raman spectroscopy indicate that the quality of GaN is very good. Spot mode CL measurement signifies intense near band edge emission as compared with yellow luminescence (YL). During scanning over an area, the YL intensity could be controlled by the electron beam dwell time (DT). The YL intensity decreases with the increase of DT and saturates beyond a threshold value due to overexposure of a given pixel leading to non-radiative emission. But for shorter dwell times repeated excitations of a given pixel increase the intensity of YL. These results may be explained invoking the decay time and density of defects responsible for YL. Control over YL intensity will be useful for assessing low defect concentrations, their origin and also to increase spatial resolution of CL measurements on nanostructures.

  10. Optically stimulated luminescence from quartz measured using the linear modulation technique

    DEFF Research Database (Denmark)

    Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

    2000-01-01

    The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonically...... stimulated component occurs at a shorter time. This allows the separation of the overlapping OSL components, which are assumed to originate from different traps. The LM-OSL curve from quartz shows an initial peak Followed by a broad one. Deconvolution using curve fitting has shown that the composite OSL...... curve from quartz can be approximated well by using a linear combination of first-order peaks. In addition to the three known components, i.e. fast, medium and slow components from continuous-wave-OSL studies, an additional slow component is also identified for the first time. The dose responses...

  11. Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release.

    Science.gov (United States)

    Büldt, Laura A; Wenger, Oliver S

    2017-11-01

    Some complexes of Cr(iii) and Cr(0) have long been known to exhibit interesting photophysical and photochemical properties, but in the past few years important conceptual progress was made. This Perspective focuses on the recent developments of Cr(iii) complexes as luminophores and dyes for solar cells, their application in photoredox catalysis, their use as sensitizers in upconversion processes, and their performance as photochemical nitric oxide sources. The example of a luminescent Cr(0) isocyanide complex illustrates the possibility of obtaining photoactive analogues of d(6) metal complexes that are commonly made from precious metals such as Ru(ii) or Ir(iii). The studies highlighted herein illustrate the favorable excited-state properties of robust first-row transition metal complexes with broad application potential.

  12. Sensitized luminescence of LaF3:Eu3+ nanoparticles through pyromellitic acid.

    Science.gov (United States)

    Li, S Wen; Ren, H Juan; Ju, S Guang

    2014-05-01

    The LaF3 nanoparticles doped with different concentration Eu3+ ions are prepared by a simple and low temperature synthetic route. The nanoparticles with the size of about 3.5 nm are roughly spherical and monodisperse. The emission of Eu3+ ions is sensitized through pyromellitic acid bonded onto the surface of nanoparticles. The structure, morphology, photoluminescence properties and fluorescence dynamics are studied systemically. The results show that the sensitized nanoparticles have a broad absorption band in the UV domain and high asymmetry radio, and enhanced Eu3+ luminescence by "antenna effect" of ligands. The excited state lifetimes of sensitized nanoparticles are longer than those of un-sensitized nanoparticles and corresponding europium complexes.

  13. Near-infrared ultrabroadband luminescence spectra properties of subvalent bismuth in CsI halide crystals.

    Science.gov (United States)

    Su, Liangbi; Zhao, Hengyu; Li, Hongjun; Zheng, Lihe; Ren, Guohao; Xu, Jun; Ryba-Romanowski, Witold; Lisiecki, Radosław; Solarz, Piotr

    2011-12-01

    We observed two ultrabroadband near-infrared (NIR) luminescence bands around 1.2 and 1.5 μm in as-grown bismuth-doped CsI halide crystals, without additional aftertreatment. Dependence of the NIR emission properties on the excitation wavelength and measurement temperature was studied. Two kinds of NIR active centers of subvalent bismuth and color centers were demonstrated to coexist in Bi:CsI crystal. The eye-safe 1.5 μm emission band with an FWHM of 140 nm and lifetime of 213 μs at room temperature makes Bi:CsI crystal promising in the applications of the ultrafast laser and ultrabroadband amplifier. © 2011 Optical Society of America

  14. Luminescent visualization of latent fingerprints by direct reaction with a lanthanide shift reagent.

    Science.gov (United States)

    Caldwell, J P; Henderson, W; Kim, N D

    2001-11-01

    The utilization of the lanthanide shift reagent tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium (III) [Eu(fod)3] as a simple one-step reagent for the luminescent visualization of latent fingerprints has been investigated. UV excitation of Eu(fod)3-treated prints, achieved by using a hand-held UV lamp or a Polilight, results in an orange emission at 614 nm. Time-resolved imaging is not required for visualization. Visualization of latent fingerprints on paper under the conditions used, although good, was found to be inferior to that obtained by standard DFO (1,8-diazafluoren-9-one) treatment, whereas visualization of prints obtained on aluminum drink cans and galvanized iron proved superior to that obtained by Superglue/panacryl treatment. Eu(fod)3 treatment can also be used first without compromising subsequent ninhydrin or DFO treatment, making it a 'nothing-to-lose" reagent.

  15. Power dependent effects in photoluminescence vs voltage scans of GaAs/electrolyte junctions using picosecond pulse excitation

    Energy Technology Data Exchange (ETDEWEB)

    Kauffman, J.F.; Balko, B.A.; Richmond, G.L. [Univ. of Oregon, Eugene, OR (United States)

    1992-07-23

    Photoluminescence from n-GaAs has been measured as a function of applied voltage under excitation with a picosecond laser at three excitation power levels. A large increase in the photoluminescence intensity at the flat band potential is observed as the excitation power is increased. Analysis of the data with the modified dead layer model shows that the surface minority trapping velocity decreases as the laser power is increased. The authors attribute this to a saturation of surface minority carrier traps resulting from picosecond pulse excitation and compare the results with a companion study in which surface minority trapping velocities at the flat band potential are determined from luminescence decay profiles. 8 refs., 3 figs.

  16. Axonal Excitability in Amyotrophic Lateral Sclerosis : Axonal Excitability in ALS.

    Science.gov (United States)

    Park, Susanna B; Kiernan, Matthew C; Vucic, Steve

    2017-01-01

    Axonal excitability testing provides in vivo assessment of axonal ion channel function and membrane potential. Excitability techniques have provided insights into the pathophysiological mechanisms underlying the development of neurodegeneration and clinical features of amyotrophic lateral sclerosis (ALS) and related neuromuscular disorders. Specifically, abnormalities of Na+ and K+ conductances contribute to development of membrane hyperexcitability in ALS, thereby leading to symptom generation of muscle cramps and fasciculations, in addition to promoting a neurodegenerative cascade via Ca2+-mediated processes. Modulation of axonal ion channel function in ALS has resulted in significant symptomatic improvement that has been accompanied by stabilization of axonal excitability parameters. Separately, axonal ion channel dysfunction evolves with disease progression and correlates with survival, thereby serving as a potential therapeutic biomarker in ALS. The present review provides an overview of axonal excitability techniques and the physiological mechanisms underlying membrane excitability, with a focus on the role of axonal ion channel dysfunction in motor neuron disease and related neuromuscular diseases.

  17. Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: a new luminescent uranyl benzoate specie.

    Science.gov (United States)

    Kumar, Satendra; Maji, S; Joseph, M; Sankaran, K

    2015-03-05

    Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3](-) which is highly luminescent. In particular, three sharp bands at 431, 443, 461nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68μs which is much more compared to the lifetime of uncomplexed uranyl (20μs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3](-) specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Thermoluminescence, luminescence optically stimulated and creation of defects in alkaline halogenides contaminated with Europium; Termoluminiscencia, luminiscencia opticamente estimulada y creacion de defectos en halogenuros alcalinos contaminados con Europio

    Energy Technology Data Exchange (ETDEWEB)

    Barboza F, M. [Centro de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, 83190 Hermosillo, Sonora (Mexico)

    1999-07-01

    The alkaline halogenides have been subject matter of investigations related with the search of sensor materials for X-ray bidimensional images or optical memories. The understanding of the damage formation processes generated by ionizing and non-ionizing radiations is important for the correct design of devices that working as detectors and dosemeters of both type of radiations. In this work we present the investigation results related with the defects produced by the ionizing radiation type X and ultraviolet light in the range of 200-360 nm in crystals of KCl: Eu{sup 2+} and KBr:Eu{sup 2+}. It is examined the thermoluminescence and luminescence spectra with the purpose of identifying the exciton processes, owing to the excitation of the halogenide ions in which the primary defects correspond to the F and H centers. It has been found that the 400-600 nm emission is associated with the luminescence type that in his turn can be associated with autotrapped excitons perturbed by the impurity. On the other hand, it is examined the emission spectra of the luminescence optically stimulated in crystals of KBr: Eu{sup 2+} and KCl: Eu{sup 2+} finding too that such materials would be used as optical memories susceptible of to store information, and through of photostimulation to read this. It was determined that the F centers participate in the luminescence optically stimulated in these crystals, as well as too in the recombination processes responsible by the thermoluminescent emission. (Author)

  19. Characterization and luminescent properties of Eu{sup 3+} doped Gd{sub 2}Zr{sub 2}O{sub 7} nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Rabasovic, M.S., E-mail: majap@ipb.ac.rs [Institute of Physics, University of Belgrade (Serbia); Sevic, D. [Institute of Physics, University of Belgrade (Serbia); Krizan, J. [Faculty for Mechanical Engineering, University of Ljubljana (Slovenia); Terzic, M. [Faculty of Science, University of Novi Sad (Serbia); Mozina, J. [Faculty for Mechanical Engineering, University of Ljubljana (Slovenia); Marinkovic, B.P.; Savic-Sevic, S. [Institute of Physics, University of Belgrade (Serbia); Mitric, M. [Vinča Institute of Nuclear Science, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Rabasovic, M.D.; Romcevic, N. [Institute of Physics, University of Belgrade (Serbia)

    2015-02-15

    Highlights: • Nanopowders Gd{sub 2}Zr{sub 2}O{sub 7} doped by europium ions (Eu{sup 3+}) have been synthesized. • Their luminescence properties have been measured at room temperature. • The temporal evolution of laser induced phenomena are presented using time-resolved technique. • Lifetime analysis for luminescence bands in emission spectra has been done. - Abstract: Nanopowders based on gadolinium zirconium oxide (Gd{sub 2}Zr{sub 2}O{sub 7}) doped by europium ions (Eu{sup 3+}) were successfully prepared using a flame combustion method. This material is suitable for various optical devices. The structure of prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques. The luminescence properties of synthesized nanopowders were characterized by emission spectra and luminescence lifetimes by using the streak camera system. PL spectra were obtained at three different excitation wavelengths (Optical Parametric Oscilator (OPO) at 360 nm, laser diode at 365 nm and Ar laser line at 514.5 nm). The strong emission lines at 611 nm and 630 nm corresponding to the {sup 5}D{sub 0} → {sup 7}F{sub 2} long lived transition could be used as a new red light source in optical devices.

  20. Intramolecular deactivation processes of electronically excited Lanthanide(III) complexes with organic acids of low molecular weight

    Science.gov (United States)

    Burek, Katja; Eidner, Sascha; Kuke, Stefanie; Kumke, Michael U.

    2018-02-01

    The luminescence of Lanthanide(III) complexes with different model ligands was studied under direct as well as sensitized excitation conditions. The research was performed in the context of studies dealing with deep-underground storages for high-level nuclear waste. Here, Lanthanide(III) ions served as natural analogues for Actinide(III) ions and the low-molecular weight organic ligands are present in clay minerals and furthermore, they were employed as proxies for building blocks of humic substances, which are important complexing molecules in the natural environment, e.g., in the far field of a repository site. Time-resolved luminescence spectroscopy was applied for a detailed characterization of Eu(III), Tb(III), Sm(III) and Dy(III) complexes in aqueous solutions. Based on the observed luminescence the ligands were tentatively divided into two groups (A, B). The luminescence of Lanthanide(III) complexes of group A was mainly influenced by an energy transfer to OH-vibrations. Lanthanide(III) complexes of group B showed ligand-related luminescence quenching, which was further investigated. To gain more information on the underlying quenching processes of group A and B ligands, measurements at different temperatures (77 K ≤ T ≤ 353 K) were performed and activation energies were determined based on an Arrhenius analysis. Moreover, the influence of the ionic strength between 0 M ≤ I ≤ 4 M on the Lanthanide(III) luminescence was monitored for different complexes, in order to evaluate the influence of specific conditions encountered in host rocks foreseen as potential repository sites.