最新刊期
卷 10 ， 期 4 ， 1989
- 摘要：In recent years, the research on Ⅱ-Ⅵ compound semiconductors such as ZnSe and CdS has special attention. The most interesting work is to study the free exciton emission in the Ⅱ-Ⅵ crystals under high excitation density[1]. Saito et al[2]. observed E and P bands in ZnSe in photoluminescence (PL) within 4.2-65K,which they attributed to exciton-electron(Ex-e)and exciton-exciton (Ex-Ex) interaction, respectively. Colak et al[3]. reported the stimulated emission in ZnSe crystal excited by electron beam. L. Ma et al. observed the P band excited by N2 Laser in VPE ZnSe epilayer at 64K. Up to now, there has been no report on Ex-Ex interaction in VPE ZnSe epilayer under high excitation density at 77K.In this work,a new band PA Was found at the low energy side of EA band under high excitation density. The origin of the new PA band was investigated.The ZnSe epilayer used in this work was grown on (100) GaAs substrate with VPE method. The ZnSe epilayer was excited by N2 Laser with the pulse width of 10ns, repetition frequency of 10Hz and the maximal pulse density of 2MW/cm2. PL spectra were measured using a grating spectrograph of model 44W with C31034 cooled photomultiplier.Fig.1 and Fig.2 show the PL spectra of the selected (specimen A) and ordinary (specimen B) ZnSe single crystal epilayers under different excitation . densities at 77K.102|48|1更新时间：2020-08-11
- 摘要：YAG:Er laser crystals were grown by Czochralski technique with Er3+ ion concentrations of 1.635×1021/cm3, 1.156×1021/cm3, 0.044×1021/cm3 and 0.029×1021/cm3 respectively. The spectral properties of YAG:Er3+ crystals were studied and the absorption cross sections were obtained. It is noted that YAG:Er3+ laser is optically pumped because there is absorption exsting in ultraviolet, visible and near infrared ranges. The energy gaps between some pairs of Er3+ levels in the YAG:Er3+ coincide each other,which can cause the cross relaxation process.By analysing the spectra of YAG:Er3+ crystal, the actions of radiative transition from 4S3/2、4I9/2、4I11/2 and 4I13/2 to 4I15/2 levels are discussed.The cross relaxation process between certain pairs of Er3+ levels in YAG:Er3+ is a nonradiative process under multipole interaction, in which dipole-dipole interactions are considered to play a dominant role. The fluorescence of 4I9/2 and 4S3/2 levels is quenched with the increase of Er3+ concentration, and that of 4I11/2 level presents an increase. For 4S3/2、4I9/2和4I13/2 there is an optimum concentration.111|38|2更新时间：2020-08-11
- 摘要：Recent years there has been considerable interest in the spontaneous and Stimulated emission of ZnSe crystals[1-3]. We have studied the effect of ZnSe crystal quality on its blue electroluminescence[4]. In this paper we rcport the effect of ZnSe single crystal quality on the high density excitation luminescence.Three types of ZnSe single crystal with different starling materials were grown by sublimation in our laboratory[4]. These were 408, 413 and 420 ZnSe single crystals with (110) surface. The starting material of 408 single crystal was ZnSe powder produced by direct synthesis from 6N-Zn and 5N-Se. The starting material of 413 and 420 single crystals was also ZnSe powder produced by sublimation once and twice from the starting material of 408 single crystal, respectively. Low resistivity crystals used in this experiment were obtained by annealing the single crystals in molten zinc at 900℃ for 80-120 hours118|60|0更新时间：2020-08-11
- 摘要：In principle all atoms in a finite solid are in a surface region. However the precision of measurement of many "bulk" parameters is such that the effects of the surface are below the limit of detection if thickness of the solid is more than a few tens of microns. Hence the effective surface region in practice is from a few atomic layers to several microns. (For insulators, the field from a surface charge can penetrate up to a few centimeters[1].) As we know, the mean particle size of powder DCEL phosphors is about 1-3μm. Therefore the surface effect on DCEL devices must be Very obvious. But there is no report on it up to now. In this work, Thermally Stimulated Current(TSC) method was used to study the surface state levels of DCEL panels, and two surface electron-trap levels were measured for the first time.104|45|2更新时间：2020-08-11
- 摘要：ACEL characteristics of metal Er and ErF3 doped thin films with different doping concentration have been studied. The relation of ACEL brightness with doping concentration shows that for ACEL the optimum doping concentration of ZnS:ErF3 thin film is 5×103g/g. It is lower than that of ZnS:Er3+ thin film (1×10-2g/g). The emission spectra of the two samples are obviously different. At nearly the same concentration, the red emission peak is stron-ger in ZnS:ErF3 than in ZnS:ErF3 thin film. The decay of excited state 2H11/2 is also different in two samples. At lower concentration (-10-3g/g), the decay of excited state 2H11/2 in ZnS:Er3+ thin film obeys single exponential form, but the decay of excited state 2H11/2 in ZnS:ErF3 thin film consists of two componentry-fast and "slow exponential "forms. We have studied the relation of latio of green emission peak to red one with applied voltage. This ratio increases with the applied voltage in" ZnS:Er3+ thin film when the concentration is low (-10-3g/g), but remains unchanged in ZnS:ErF3 thin film. At higher concentration (~10-2g/g) this ratio decrease with applied voltage in ZnS:ErF3 thin film. Therefore, the interaction between RE ions, the cross relaxation, becomes important when the concentration gets higher. This process is affected by surroundings of RE ions. The excistence of F- ion enhances the cross relaxation process and it is the main reason why ZnS:ErF3 thin film has lower optimum concentration for ACEL. Although ErF3 "lumocen" has large impact cross section but the optimum concentration is lower. To obtain higher green ACEL thin film, ZnS:Er3+ is better than ZnS:ErF3.106|45|0更新时间：2020-08-11
- 摘要：In this paper, fluorescent lifetimes of Sm3+ in SmxLa1-xP5O14 single crystals originating from transitions between 4G5/2 and 6HJ (J=5/2, 7/2, 9/2,11/2) energy levels and Dy3+ in DyxY1-xP5O14 single crystal originating from transitions between 4F9/2 and 6HJ (J=15/2, 13/2, 11/2, 9/2) energy levels at several concentrations were measured and investigated in detail.The measurement of lifetime was completed by pulse decay curve method and time resolved fluorescent spectrum method, the relative crror<15%. The set-up of lifetime measuring consists of a N2 laser and a photoelectricity detecting system with pulsed gated Boxcar averager. Measurement of fluorescent intensities of the rare earth pentaphosphate single crystals was completed by MPF-4 Fluorimetcr.109|26|0更新时间：2020-08-11
- 摘要：A scries of (Ce, Gd, Mn)Mg5O10 phospnors nave Dccn synthesized by solid state reaction method. The influences of the temperature,the fire time and the ratio of the raw material were investigated. X-ray diffraction patterns show that the structure of (Cc, Gd, Mn)MgB5O10 is the same as that of LaMgB5O10 and both of them belong to monoclinic System, space group P21/c.The EPR results show that the manganese ion has a valency of two in (Cr, Gd, Mn)MgB6O10.The spectra of (Ce0:2La0:8)MgB6O10, (Gd0:7La0:3) MgB5O10,(Mn0:05 La0:95)MgB5O10, (Ce0:2Mn0:05BLa0:75)Mg5O10, (Gd0:59Mno:06 )MgB5O10, (Ce0:2La0:8)MgB5O10 and (Ce0:2Mn0:05BLa0:75))MgB5O10 have been measured. The spectra show that the processes of energy transfer in the phosphors are Ce3+-Mn2+, Gd3+-Mn2+ and Ce3+-Gd3+-Mn2+.97|50|4更新时间：2020-08-11
- 摘要：It is interesting to investigate the rare-earth (RE) ion activated ZnS phosphor because ZnS:Cu+, ZnS:Ag+ and ZnS:Mn2+phosphors have high luminescence efficiency. Luminescence of ZnS:RE3+ has been well Studied by Some authors in various laborateries[1,2,3], but Eu2+ activated ZnS phosphor was seldom reported .In the investigation of RE activated ZnS material systems, we pay attention to the luminescence properties of the System which is activated by Eu2+ ions having f-d transition. We studied the preparation and fluorescence properties of ZnS:Eu2+ phosphor systematically.The preparation procedure of ZnS:Eu2+ was as follows. The dried mixture of ZnS with Eu(NO3)3 was put in a muff with two fused silica tubes. Sulfur and active cabon were placed in the gap between the two tubes. The mixture was fired in a furnace at the temperature of 1150-1200℃ for 1 hr .The concentration of Eu2+ in ZnS for all of the samples was about 0.07 a%.Spectral properties were discussed in detail and interesting afterglow was found for the first time. The emission spectra consist of a main band of 550 nm and a weak band of 650nm corresponding to 380nm and 338nm excitation bands, respectively. Thermoluminescence, the dependence of emission spectra on temperature and the effect of temperature on the decay time were observed. According to the results two kinds of associated europium center were presumed. The dependence of emission spectra of the phosphor on Cd2+ was also measured. It is considered that the short fluorescence lifetime is related to the electron traps in the band gap of ZnS. In addition, cathodoluminescence charatceris-tics were investigated too. It was found that ZnS:Eu2+ showed a long afterglow up to 50 ms, and its brightness dependence on applied voltage was better than standard P-1 Zn2SiO4:Mn phosphor. Therefore the phosphor ZnS:Eu2+ may be useful for industry in the future.120|59|5更新时间：2020-08-11
- 摘要：The excitation energy transfer between molcculars of laser dye dimethyl-POPOP and DCM in solution has been studied by measuring the fluorescence emission and decay kinetics. The results obtained show that the fluorescence of photoexcited dimethyl-POPOP was quenched by added DCM with the increase of the concentration of DCM. Though the fluorescence lifetime of DCM increased with the increase in dimethyl-POPOP's fluorescence quenching adding DCM did not change the fluorescence lifetime of dimethyl-POPOP anyway. The similar effect was also observed in the case of increasing the concentration of dimethyl-POPOP, when the DCM in solution was kept at constant concentration. These results convincingly indicate that there is an excitation transfer from photoexcited dimethyl-POPOP to DCM via radiative transfer mechanism. As a consequence the wavelength of incident radiation can be converted directly from UV into spectral region above 600nm. In addition, the possible approac-es to improve the efficiency of this process are discussed in brief.149|49|0更新时间：2020-08-11
- 摘要：The formation and luminescence properties of the complex of terbium ion (Tb3+)-salicylates (methyl salicylate MS, and phenyl salicylate PS) and the energy transfer processes from the complex to europium ion (Eu3+) have been investigated by use of the steady state and transient state time-resolved emission spectroscopy.From the fluorecence spectra and lifetime data of the MP system (Table 1), it can be seen that, with the increase of Tb3+ concentration, the fluorescence intensity of the MP decreases and the characteristic emission of Tb3+ ions increases.Plots of F0/F against the concentration of Tb3+ ions satisfy the Stern-Volmer equation.But the fluorescence lifetime remains constant, τ0/τ≈1. this is a typical static quenching process[4]. Absorption changes are also observed in the absorption spectra and the absorption peaks of complex appear at longer wavelength than those of MS and PS do.We can conclude from the study that Tb3+ ions form steady complex in ground state with MP, MS by certain proportion and transfer the absorption energy effectively to center Tb3+ ions. The terbium luminescence intensity is increased by many times in the complex than that in the studied systems.118|71|1更新时间：2020-08-11
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