共查询到20条相似文献,搜索用时 609 毫秒
1.
V. Yu. Ivanov V. A. Pustovarov E. S. Shlygin A. V. Korotaev A. V. Kruzhalov 《Physics of the Solid State》2005,47(3):466-473
Low-temperature (T = 7 K) time-resolved selectively photoexcited luminescence spectra (2–6 eV) and luminescence excitation spectra (8–35 eV) of wide-bandgap chrysoberyl BeAl2O4, phenacite Be2SiO4, and beryl Be3Al2Si6O18 crystals have been studied using time-resolved VUV spectroscopy. Both the intrinsic luminescence of the crystals and the luminescence associated with structural defects were assigned. Energy transfer to impurity luminescence centers in alexandrite and emerald was investigated. Luminescence characteristics of stable crystal lattice defects were probed by 3.6-MeV accelerated helium ion beams. 相似文献
2.
The properties of polycrystalline CdTe with a grain size of 5–30 μm have been investigated using the microphotoluminescence
methods of spectral analysis and topography. This material has been prepared by direct synthesis in a vapor flow of components
at a low temperature. The dominance of the Y and Z bands in the spectra reflects a nonequilibrium character of the crystallization processes. The superlinear dependences of
the luminescence intensity on the level of the band-to-band excitation indicate the exciton nature of the corresponding transitions.
The activation energies for temperature quenching of luminescence in the temperature range T = 100–150 K are found to be 120 meV for the Y luminescence and 180 meV for the Z luminescence, which correspond to the dissociation of excitons bound to defects with the transition of charge carriers to
the conduction and valence bands. The monochromatic topography data indicate that Y and Z defects have different material bases. 相似文献
3.
M. M. Chugunova I. A. Kamenskikh V. V. Mikhailin S. A. Usenko 《Optics and Spectroscopy》2010,109(6):887-892
We present the results of studying the luminescence properties of transparent ceramics Y3Al5O12:Yb obtained by the vacuum sintering and nanocrystalline technology. In the course of research, we measured the luminescence
and luminescence excitation spectra, as well as the temperature and kinetic behavior of luminescence. Our results are analyzed
in comparison with the characteristics of corresponding single crystals. We revealed that processes of generation and relaxation
of electronic excitations that occur in ceramics, in particular, in the charge transfer state, are similar to processes occurring
in crystals. The behavior of two charge-transfer luminescence bands at 340 and 490 nm is studied. In the range 300–600 nm,
we revealed a broad emission band of radiation of other type, which is also observed in spectra of undoped ceramics. This
broad band is attributed to F+ centers. Emission and excitation spectra of charge transfer luminescence at a maximum of the temperature dependence of 100
K are measured for the first time. We found that, upon excitation in the charge transfer band, luminescence in ceramics is
more intense than in single crystals with similar concentrations of Yb and has a higher quenching temperature. 相似文献
4.
O. V. Ovchinnikov A. B. Evlev M. A. Efimova V. G. Klyuev A. N. Latyshev A. N. Utekhin A. M. Kholkina 《Journal of Applied Spectroscopy》2005,72(6):809-813
An anti-Stokes luminescence band with λmax = 515 nm of microcrystals of solid AgCl0.95I0.05 solutions excited by a radiation flux of density 1013–1015 quanta/cm2·sec in the range 600–800 nm at 77 K was detected. It is shown that the intensity of this luminescence and the frequency of
its excitation depend on the prior UV-irradiation of samples. Analysis of the stimulated-photoluminescence spectra and the
anti-Stokes luminescence excitation spectra of the indicated microcrystals has shown that to the centers of anti-Stokes luminescence
excitation correspond local levels in the forbidden band of the crystals. These states are apparently due to the atomic and
molecular disperse silver particles that can be inherent in character or formed as a result of a low-temperature photochemical
process.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 738–742, November–December, 2005. 相似文献
5.
M. D. Zimin V. P. Dresvyanskiy A. L. Rakevich E. F. Martynovich N. M. Kozhevnikova 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(1):78-80
The spectral properties of a promising laser material, ternary molybdate Li3Ba2Gd3(MoO4)8:Nd3+, are studied (i.e., its optical absorption spectra, luminescence spectra, kinetic of luminescence decay, and temperature dependence of luminescence). Luminescence of the crystalline matrix is detected, and the temperature dependence of its intensity and reabsorption by neodymium are investigated. 相似文献
6.
S. V. Zaitsev Yu. V. Ermolaeva N. A. Matveevskaya I. I. Zver’kova A. V. Tolmachev 《Optics and Spectroscopy》2017,122(6):906-911
A study of the luminescence of Eu3+ ions in Y2O3 nanospheres indicates a significant influence of the porous structure of nanoparticles on the luminescence of dopant ions. It is shown that filling the nanopores of initially porous Y2O3 nanospheres shortens the decay time of the spontaneous luminescence of doping europium ions. The change in the decay time is associated with the change in the effective refractive index of the porous nanospheres. 相似文献
7.
A. M. Ulyashenko N. V. Nikonorov A. K. Przhevuskii 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(2):159-163
Forsterite nano glass-ceramics doped with tetravalent chromium ions is synthesized, and the spectral and luminescence properties of this material are investigated. A technique for measuring the absolute quantum yield of Cr4+ luminescence is proposed and implemented experimentally. The luminescence spectra and the absolute quantum yield of Cr4+ luminescence of the forsterite nano glass-ceramics are compared with those of the forsterite single crystal and calcium aluminate glass doped with tetravalent chromium ions. 相似文献
8.
S. V. Zaitsev A. N. Gruzintsev Yu. V. Yermolayeva N. A. Matveevskaya I. I. Zverkova G. A. Emelchenko A. V. Tolmachev 《JETP Letters》2017,106(3):145-151
The kinetics of luminescence of Eu3+ ions in Lu2O3:Eu nanospheres with diameters of 100–270 nm and a small standard deviation of the size distribution <15% has been studied. A sharp decrease in the decay time of luminescence of Eu3+ ions in the red range with an increase in the diameter of nanospheres has been attributed to the appearance of a photon mode accelerating spontaneous luminescence, which is confirmed by the calculation of ranges of existence of whispering-gallery modes in studied nanospheres. 相似文献
9.
B. N. Kazakov A. V. Mikheev O. G. Goriev S. L. Korableva V. V. Semashko 《Optics and Spectroscopy》2016,121(4):523-533
The results of a complex analysis of the excitation mechanisms of the up conversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are presented. The spatial distribution of the upconversion luminescence intensity is studied by the photographs of longitudinal cross sections at different positions of the laser beam waist with respect to the sample. The surface power density of the pump laser diode radiation (0.755 W, λ = 933 nm) was changed by focusing the beam (similar to Z-scanning). The dependences of the longitudinal luminescence cross sections, as well as of the spectral and kinetic characteristics of Ho3+ and Yb3+ luminescence, on the position of the laser beam waist are determined. It is found that there exist two different mechanisms of the population of the energy levels of Ho3+ ions from which green and red luminescence occur, namely, cooperative sensitization of luminescence and absorption of induced photon groups (JETP Letters, 102 (5), 279 (2015)). It is shown that the contributions of these mechanisms vary both in time and over the crystal volume. All the observed spatial, spectral, and temporal specific features of the upconversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are qualitatively explained. 相似文献
10.
K. A. Subbotin V. A. Smirnov E. V. Zharikov A. V. Gaĭster I. A. Shcherbakov L. D. Iskhakova 《Optics and Spectroscopy》2000,89(1):56-61
Single crystals of a new promising laser material, Cr4+-doped germanium eucryptite Cr4+:LiAlGeO4, are grown from the melt for the first time. The crystals grown exhibit nonlinear optical properties. Absorption and luminescence spectra of the crystals and their luminescence decay are studied at various temperatures. The luminescence lifetime at 1.2 μ m at 300 K is 10 μ s. Active centers in the crystal are identified, and crystal field parameters are estimated. 相似文献
11.
Absorption and photoluminescence properties of silver clusters in SiO<Subscript>2</Subscript> matrix
Igor A. Gladskikh Polina V. Gladskikh Tigran A. Vartanyan 《Optical and Quantum Electronics》2017,49(1):41
Absorption and luminescence properties of silver nanoclusters embedded in SiO2 matrixes were studied experimentally. Thin SiO2 films with different amount of silver were produced by co-deposition of Ag and SiO2 onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350–450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties. 相似文献
12.
X‐ray‐excited optical luminescence (XEOL) emission and excitation spectra as well as the EXAFS signal of CdWO4 were measured in the energy region of the Cd and W absorption edges. From EXAFS refinement, structural parameters such as number of atoms, distance from the absorbing atom and width of coordination shells in the W neighborhood were determined. The role of W–O interactions on the intrinsic luminescence of CdWO4 is discussed. The efficiencies of conversion, transfer and emission processes involved in the scintillation mechanism showed to be high when self‐trapped excitons are formed locally by direct excitation of W ions. Annihilation of these excitons provides the characteristic scintillation of CdWO4, a broad band emission with maximum at 500 nm. The presence of two energetically different O positions in the lattice gives rise to the composite structure of the luminescence band, and no influence of extrinsic defects was noticed. A mismatch between the X‐ray absorption coefficient and the zero‐order luminescence curves corroborates that the direct excitation of Cd ions induces secondary electronic excitations not very effective in transferring energy to the luminescent group, WO6. 相似文献
13.
Near-infrared broadband luminescence from 1100 to 1600 nm was observed in Bi2O3-GeO2 binary glasses. The strongest emission can be observed with 30 mol % Bi2O3 when pumped at 808 nm. The lifetimes of all samples are longer than 200 μs. The glass network was studied by Raman spectra
and Bi+ ions are proposed as the infrared luminescence centers in this glass system. Thermal treatment in air results in partly oxidation
of Bi+ to Bi2+. 相似文献
14.
The effect of temperature on the spectral luminescence characteristics of PbWO4:Tb3+ crystals with synchrotron and laser excitation is studied. If PbWO4:Tb3+ is excited by synchrotron radiation with λ = 88 nm at 300 K, a faint recombination luminescence of the impurity terbium is
observed against the matrix luminescence. When the temperature is reduced to 8 K, the luminescence intensity of PbWO4:Tb3+ increases by roughly an order of magnitude and the characteristic luminescence of the unactivated crystal is observed. Excitation
of PbWO4:Tb3+ by a nitrogen laser at 300 K leads to the appearance of emission from Tb3+ ions. At 90 K, a faint matrix luminescence is observed in addition to the activator emission. The formation of the luminescence
excitation spectra for wavelengths of 60–320 nm is analyzed and the nature of the emission bands is discussed. 相似文献
15.
P. A. Rodnyĭ I. V. Berezovskaya A. S. Voloshinovskii G. B. Stryganyuk A. S. Potapov 《Optics and Spectroscopy》2003,94(4):550-555
Spectral and kinetic characteristics of the luminescence and luminescence excitation spectra of polycrystalline SrB4O7:Pr (1%) and SrB6O10:Pr (1%) samples are studied at 150–170 K. The samples show an intense luminescence band in the vicinity of 405 nm (1 S 0→1 I 6 transitions of Pr3+) and shorter wavelength bands also assigned to transitions from the 1 S 0 level. The main luminescence decay constant is ~2×10?7 s. The excitation spectra of the 1 S 0 luminescence in these crystals are significantly different. The SrB4O7:Pr crystal shows three well-resolved bands at 6.14, 6.55, and 6.91 eV in the region of the 4f 2→4f 15d transitions and a complex structure in the region of interband transitions (7.1–20 eV), whereas the SrB6O10:Pr crystal shows a weakly structured band at 6.31 eV and no excitation in the region of the interband transitions. The physical mechanisms that may be responsible for the observed features of the spectra are discussed. 相似文献
16.
V. S. Dneprovskii E. A. Zhukov V. L. Lyaskovskii M. V. Ryzhkov I. V. Tolpeikin A. I. Shatalin 《Physics of the Solid State》2004,46(9):1755-1760
Nonlinear dependence of the CdSe/Al2O3 quantum wire luminescence intensity on the photoexcitation level and an asymmetric broadening of luminescence spectra accompanied by a high-frequency shift of the maximum are observed and explained in terms of the dominant filling of exciton phase space in wires with different cross sections. 相似文献
17.
I. N. Ogorodnikov N. E. Poryvai I. N. Sedunova A. V. Tolmachev R. P. Yavetskiy 《Optics and Spectroscopy》2011,110(2):266-276
The luminescence and thermally stimulated recombination processes in lithium borate crystals Li6Gd(BO3)3 and Li6Gd(BO3)3:Ce have been studied. The steady-state luminescence spectra under X-ray excitation (X-ray luminescence), temperature dependences
of the intensity of steady-state X-ray luminescence (XL), and thermally stimulated luminescence (TSL) spectra of these compounds
have been investigated in the temperature range of 90–500 K. The intrinsic-luminescence 312-nm band, which is due to the 6
P
J
→ 8
S
7/2 transitions in Gd3+ matrix ions, dominates in the X-ray luminescence spectra of these crystals; in addition, there is a wide complex band at
400–420 nm, which is due to the d → f transitions in Ce3+ impurity ions. It is found that the steady-state XL intensity in these bands increases several times upon heating from 100
to 400 K. The possible mechanisms of the observed temperature dependence of the steady-state XL intensity and their correlation
with the features of electronic-excitation energy transfer in these crystals are discussed. The main complex TSL peak at 110–160
K and a number of minor peaks, whose composition and structure depend on the crystal type, have been found in all crystals
studied. The nature of the shallow traps that are responsible for TSL at temperatures below room temperature and their relation
with defects in the lithium cation sublattice are discussed. 相似文献
18.
Yu. V. Zorenko V. I. Gorbenko G. B. Stryganyuk V. N. Kolobanov D. A. Spasskii K. Blazek M. Nikl 《Optics and Spectroscopy》2005,99(6):923-931
The luminescence of excitons and antisite defects (ADs) was investigated, as well as the specific features of the excitation energy transfer from excitons and ADs to the activator (Ce3+ ion) in phosphors based on Lu3Al5O12:Ce (LuAG:Ce) single crystals and single-crystalline films, which are characterized by significantly different concentrations of ADs of the Lu Al 3+ type and vacancy-type defects. The luminescence band with λmax = 249 nm in LuAG:Ce single-crystal films is due to the luminescence of self-trapped excitons (STEs) at regular sites of the garnet lattice. The excited state of STEs is characterized by the presence of two radiative levels with significantly different transition probabilities, which is responsible for the presence of two excitation bands with λmax = 160 and 167 nm and two components (fast and slow) in the decay kinetics of the STE luminescence. In LuAG:Ce single crystals, in contrast to single-crystal films, the radiative relaxation of STEs in the band with λmax = 253.5 nm occurs predominantly near Lu Al 3+ ADs. The intrinsic luminescence of LuAG:Ce single crystals at 300 K in the band with λmax = 325 nm (τ = 540 ns), which is excited in the band with λmax = 175 nm, is due to the radiative recombination of electrons with holes localized near Lu Al 3+ ADs. In LuAG:Ce single crystals, the excitation of the luminescence of Ce3+ ions occurs to a large extent with the participation of ADs. As a result, slow components are present in the luminescence decay of Ce3+ ions in LuAG:Ce single crystals due to both the reabsorption of the UV AD luminescence in the 4f-5d absorption band of Ce3+ ions with λmax = 340 nm and the intermediate localization of charge carriers at ADs and vacancy-type defects. In contrast to single crystals, in phosphors based on LuAG:Ce single-crystal films, the contribution of slow components to the luminescence of Ce3+ ions is significantly smaller due to a low concentration of these types of defects. 相似文献
19.
T. N. Vasilevskaya A. A. Kaplyanskii A. B. Kulinkin S. P. Feofilov 《Physics of the Solid State》2003,45(5):961-968
The properties of Cr3+-doped Li2Ge7O15 (LGO) lithium germanate nanocrystals produced in lithium germanate glasses under isothermal heating were studied. The samples were characterized by x-ray diffraction and small-angle scattering, as well as by transmission electron microscopy. The luminescence spectra of the impurity chromium measured in lithium germanate glasses containing LGO crystals revealed transitions in Cr3+ ions residing in the glass phase and in LGO crystallites starting from extremely small clusters. This provided the possibility of following the process of crystallization of the lithium germanate glass from Cr3+ luminescence spectra. The effects observed in the Cr3+ luminescence spectrum revealed a ferroelectric phase transition in LGO nanocrystals embedded in the glass. 相似文献
20.
V. F. Lebedev I. D. Ryabov A. V. Gaister A. S. Podstavkin E. V. Zharikov A. V. Shestakov 《Physics of the Solid State》2005,47(8):1504-1506
Based on the results of a comparative analysis of luminescence spectroscopy and EPR spectroscopy data, it was found for the first time that the wide-band luminescence of Cr3+ ions in a forsterite crystal is due to the Cr3+-VMg center or, in a crystal additionally doped with lithium, to a Cr3+-Li+ center. For the first time, tunable laser action was obtained with Cr3+-Li+ centers responsible for the wide-band luminescence. 相似文献