共查询到20条相似文献,搜索用时 187 毫秒
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TL spectra of undoped lead tungstate crystals exhibit glow peaks at 30 v K and 85 v K centred at 440 v nm, plus a peak at 50 v K at 530 v nm in an annealed sample. Annealing adds a 170 v K peak. Trivalent dopants of La 3+ and Y 3+ reduce the green luminescence, and Nb 5+ introduces a peak near 100 v K centred at 530 v nm; Sb introduces features between 40 v K and 90 v K and 150 and 180 v K. The luminescence emissions around 50 v K may be attributed to complex intrinsic defect centres, including (WO 4 ) m 3 . Of the four dopants studied in the present research, Sb +5 has the highest luminescence intensity. CL spectra show interesting anomalies near 170 v K which are linked to a phase change of water/ice nanoparticles trapped at dislocations. 相似文献
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Abstract The origin of the luminescence bands at 7.5 eV anv 3.8 eV appearing additionaly to the luminescence of F- and F+- centres in pure Al2O3 are investigated. The time - resolved luminescence spectra, absorption and luminescence excitation spectra as well as trap spectroscopy data depending on deviation from the stochiometry of crystals are discussed in terms of self - trapping of excitons in two configurations. The role of defects due to annihilation of excitons is considered. 相似文献
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In this paper we report on the growth, luminescence and scintillation parameters of lead tungstate (PbWO4) single crystals and typical requirements on them, important for their application as scintillating medium for the electromagnetic
calorimeter detector in a future generation of energy physics accelerators.
Presented at the 6th Joint Seminar “Development of Materials Science in Research and Education”, Karlštejn, Czech Republic,
17–19 September 1996. 相似文献
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Radio-, photo- and thermo-luminescence were measured for two sets of PbWO 4 single crystal samples doubly doped with Mo and Nb 5+ /Ta 5+ ions. Pentavalent ion codoping of PbWO 4 :Mo enhances the radioluminescence intensity to the level exceeding that of BGO scintillator. However, it introduces a new trapping level, which is reflected by the intense thermoluminescence-glow-curve peak around 100 v K. This trapping center is probably responsible for the increased occurrence of slow decay components in such doubly doped PbWO 4 . 相似文献
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The electronic structures of luminescence centers in ZnWO4, ZnWO4:Mo, and ZnWO4:Cd crystals are calculated by the configuration interaction method using embedded cluster approach. Dependencies of energies of the ground and excited electronic states of the centers on vibration coordinates are computed. The energies and oscillator strengths of radiative transitions in the luminescence centers of regular and doped zinc tungstate crystals are obtained. Formation of emission spectra of ZnWO4, ZnMoO4, and CdWO4 are analyzed using results of the calculations. 相似文献
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V. Nagirnyi S. Chernov L. Grigorjeva L. Jönsson M. Kirm A. Kotlov 《辐射效应与固体损伤》2013,168(6-12):1123-1126
A systematic spectroscopic study of single ZnWO 4 :Fe crystals with different iron concentrations has been performed under excitation by ultraviolet light, by synchrotron radiation or under photostimulation by near-infrared light. The luminescence of Fe 3+ -related centres has been studied. It is shown that iron centres of different types efficiently promote the formation of crystal defects at low temperatures. Electrons and holes can be trapped near Fe 2+ or Fe 3+ ions, which is further revealed in phosphorescence, thermostimulated or photostimulated luminescence. At room temperature the main effect of iron impurity is to reduce the light yield of a ZnWO 4 scintillator. 相似文献
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S. S. Novosad 《Technical Physics》1999,44(1):124-125
The effect of the conditions of preparation, temperature, and the action of x rays on the luminescence properties of calcium-iodide
scintillation crystals is investigated. On the basis of the results of a study of the spectral characteristics of CaI2 and CaI2:H2 crystals for optical and x-ray excitation in the temperature range 90–400 K, also taking into account the results of a study
of the luminescence properties of CaI2 crystals activated by Cl−, Br−, OH−, and Ca2+ impurities, it is suggested that the 236-nm band observed in the excitation spectra of crystals of calcium iodide may be
caused by an uncontrollable hydrogen impurity. The luminescence of these crystals with maximum at 395 nm is ascribed to radiative
recombination of excitons trapped at H− ions.
Zh. Tekh. Fiz. 69, 135–136 (January 1999) 相似文献
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We demonstrate broadband light generation by focusing two-color ultrashort laser pulses into a Raman-active crystal, lead tungstate (PbWO(4)). As many as 20 anti-Stokes and 2 Stokes fields are generated due to strong near-resonant excitation of a Raman transition. The generated spectrum extends from the infrared, through the visible region, to the ultraviolet, and it consists of discrete spatially separated sidebands. Our measurements confirm good mutual spatial and temporal coherence among the generated fields and open possibilities for synthesis of subfemtosecond light waveforms. 相似文献
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Luminescence and thermoluminescence properties of nominally pure LiF and CaWO4 crystals are compared with those of the crystalline system LiF/CaWO4. Evidence is found which clearly indicates that from the various emission bands of CaWO4 crystals only the blue one is of intrinsic nature. Luminescence decay measurements are reported. Within the spectral range of the blue tungstate band in LiF/CaWO4 four different decay times are obtained. This result is interpreted as arising from WO2-4 luminescence centres with different environments in the LiF host. 相似文献
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Abstract Recombination luminescence emission spectra, TSL and trap spectra estimated by fractional glow technique (FGT), in nominally pure and Li-, Bi- and Ho-doped CdWO4, crystals are reported. According to the investigations by FGT heterovalent impurities Li, Bi and Ho causes localized electronic states which act as traps for charge carriers. It is shown that TSL results in emission of known blue-green luminescence band by emptying of the Li+-related traps in CdWO4-Li and yellow luminescence band by emptying of the Bi3+-related traps in CdWO4-Bi. It is proposed that blue-green and yellow luminescence occur by recombination correspondingly of free holes and free electrons at different intrinsic tungstate group related luminescence centers. 相似文献
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The transient absorption spectra and kinetics were studied for undoped, lead doped and high purity SrTiO 3 single crystals. The pulsed electron beam induced transient absorption is studied in all crystals. The strong absorption at 0.8 v eV was observed only in high purity SrTiO 3 . This absorption is suggested to arise from intrinsic electron polaron. The bound electron polarons are likely responsible for absorption band at 1.4 v eV. The main luminescence band under excitation pulse is observed at 2.75 v eV. The luminescence decay is faster than that of transient absorption. 相似文献
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O. V. Rzhevskaya D. A. Spasskiĭ V. N. Kolobanov V. V. Mikhaĭlin L. L. Nagornaya I. A. Tupitsina B. I. Zadneprovskiĭ 《Optics and Spectroscopy》2008,104(3):366-373
Luminescence properties of a pure CdWO4 crystal and a CdWO4:Mo crystal doped with molybdenum in different concentrations have been investigated. The effect of molybdenum impurity on the intrinsic luminescence of CdWO4 has been found, and the role of the impurity in the formation of new luminescence centers has been investigated. The features of the formation of the intrinsic and impurity luminescence excitation spectra of CdWO4 and CdWO4:Mo crystals in the fundamental-absorption region have been considered. The reflection spectra of the CdWO4 crystal have been investigated taking into account the crystal structure anisotropy. 相似文献
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S. Burachas M. Ippolitov V. Manko S. Nikulin A. Vasiliev A. Apanasenko A. Vasiliev A. Uzunian G. Tamulaitis 《Radiation measurements》2010,45(1):83-88
Influence of irradiation on the light yield of PWO (lead tungstate, PbWO4) scintillation crystals was studied in the temperature range from ?25 °C to +60 °C. Light output and optical transmittance were simultaneously measured as a function of time under irradiation in PWO single crystals grown in first and second recrystallization cycle of raw material, doped with different lanthanides and annealed in different conditions. Increased sensitivity to irradiation and slower recovery of the initial light yield were observed at decreased temperatures. The model of tungsten oxide clusters in a regular PWO lattice is used to interpret the experimental results, and dynamics of the light yield under irradiation at different temperatures are qualitatively explained using rate equations describing composition changes in the clusters. 相似文献
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The electronic structures and absorption spectra of PWO crystals containing interstitial oxygen ions have been calculated using density functional theory code CASTEP with lattice structure optimized. It is shown by calculation that: (1) the interstitial oxygen ion in the perfect PWO crystal doesn’t bring any obvious absorption in the visible region; (2) the green emission of lead tungstate origin is closely related to the interstitial oxygen ion, and probably originates from the center of “ WO4+Oi”. 相似文献
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白钨矿结构的钨,钼酸盐晶体的光吸收边及其起因 总被引:2,自引:0,他引:2
比较了一些白钨矿结构的钨,钼酸盐晶体(如未掺杂的CaWO4,PbWO4,CaMoO,PbMoO4晶体)的透射光谱,发现这些晶体的光吸收边的相对位置用普遍认为的观点,即白钨矿结构的钨,钼酸盐晶体的光吸收边起源于具有Td对称性的W(Mo)O^2-4基团的电子从t1轨道的2e轨道的转移激发,不能给出了圆满阐释,而应代之以新的观点,作者认为这类晶体的光吸收可能起因于D2d对称的W(Mo)O^2-4基团内的 相似文献