最新刊期
卷 12 ， 期 4 ， 1991
- 摘要：The continuously tunable sum frequency output of 217.3-221.4nm has been obtained by the frequency mixing between third harmonic (355nm) of Q-YAG laser and tuning Rh. 6G dye laser in β-BaB2O4 (BBO) crystal. The largest sum frequency output energy is about 250uJ, and the conversion efficiency is about 11%. Experimental conditions to obtain the largest sum-frequency output energy are discussed.110|49|1更新时间：2020-08-11
- 摘要：A growth method for the physical vapor transport of high purity CdS single crystals in a capsule with component pressure is described. The stoichiometry of CdS crystals can be adjusted by the control of Cd temperature which is located in a reservoir. With purification technique of the starting materials. Single crystals can be grown at lower temperature than previously used. The photo luminescence spectra of CdS were measured at 11K using 457.9nm line from an Ar+ laser. It is found that the intensity of free exciton increases with times of purification while the intensity of bound exciton decreases. This is a new attempt to judge the purity of CdS single crystals by PL intensity ratio of free to bound exciton.110|52|1更新时间：2020-08-11
- 摘要：It is reported in this paper that CdxZn1-x has been used to replace ZnS as the host in order to improve SmF3 red thin film electrolu-minesence.According to the PL excitation spectra shown in Fig.2,SmF3 exhibits better EL characteristics in CdxZn1-x than in ZnS crystal.The TFEL panels prepared for the experiment were made with the usual MISIM structure. It is demonstrated in Fig. 3 and Fig. 4 that the luminescence of SmF3 in CdS doped ZnS host shows higher brightness at the same applied voltage than in pure ZnS when the dope concentration is appropriate.Comparison between the simultaneous emission of Er3+ and SmEr3+ in the two different hosts has been made to investigate the cause of brightness increase. As Er3+ is considered having approximately the same exciting cross-section, it can be deduced from Fig. 6 that Sm has larger cross-section in CdxZn1-x than in ZnS. This is probably due to the change of crystal field of Sm3+ luminecence center.However, the Cd concentration in host influences Sm3+ TFEL characteristics not only in increasing the SmEr3+ exciting cross-section, but also in causing the drop of the high field in thin film. This is because of the narrower forbidden band and higher mobility of holes and electrons of CdS.The drop of high field will destroy the SmEr3+ TFEL when the CdS dope is too high. The best value of x in CdxZn1-x obtained in our lab is around 0.13.113|31|2更新时间：2020-08-11
- 摘要：The optical properties of TiO2 semiconductor ultrafine particles with surface modification was investigated, in contrast with those of bulk and naked TiO2 ultrafine particles. The experimental results show that the strong chemical interactions between the surface of the particles and the organic molecules has significantly changed their properties.100|42|1更新时间：2020-08-11
- 摘要：Light-emitting diodes are frequently fabricated from homoepitaxial gallium phosphide films doped with nitrogen with an isoelectronic impurity. A convenient way to introduce nitrogen is by use of vapour phase dopant. The nitrogen doping of the p-and n-layer was performed by ammonia vapour. The problem of nitrogen doping in liquid phase epitaxy (LPE) is more complex than in vapour phase epitaxy where nitrogen is incorporated directly at the growth interface.In LPEthe interaction of NH3 with Ga melt and the diffusion rate of nitrogen in gallium also have to be considered. We have investigated the kinetics process of nitrogen doping in GaP-LPE using NH3 vapour dopant. The way to measure NH3 concentration of the carrier gas H2 was determined by neutralization of a HCl solution of molarity. These investigations have shown that the reaction of NH3 with Ga is present when ammonia is highly dissociated in GaP-LPE precess. It is known from equation (3) that the GaN concentration in Ga melt is directly proportional to PNH3 the partial pressure of NH3. According to Henry's law:in equilibrium, the concentration of a species within a solid is proportional to the partial pressure of that [species in the surrounding gas. Thus, the nitrogen concentration in GaP-LPE layer is directly proportial to the GaN concentration in gallium melt (i.e. the ammonia partial pressure in hytrogen as expressed in equation(4).Also we have found that nitrogen doping is a kinetics process which is strongly dependent upon the diffusion rate of nitrogen through the growth melt. Using the condition of steady state (F1=F2=F3),we get the express) ons(8), (9) for the concentration of the gallium melt-LPE growth interface C1 and the gas-gallium melt interface C0.112|41|0更新时间：2020-08-11
- 摘要：By using the elect ron-phonon interaction theory developed by Wendler and Pan Jinsheng, A calculation is given for the coupling function of electron and long wave optical surface phonon and the dispersion relation of long wave optical surface (SO) phonons in biquantum well. The general formula of the electron-phonon coupling function in multilayer polar medium is given by the equation.108|59|0更新时间：2020-08-11
- 摘要：CaS:Cu phosphors were prepared and their luminescence properties were studied. Copper is proved to be existed as monovalence in calcium sulphide from X-ray photoelectron spectra. In excitation spectra of CaS:Cu phosphors, three peaks have been observed. The peaks locate at 268nm,307nm and 400nm respectively.The peak of 268nm is overlapped between the excited state 1T2 (37700cm-1) of Cu+ ions and the absorption edge of calcium sulphide, The peak of 307nm is caused by the excited state 1E(32500cm-1) of Cu+ ions. The peak of 400nm is produced by the transformation process of Cu+→Cu2+ e.95|59|4更新时间：2020-08-11
- 摘要：Amplification in Fabry-Perot type semiconductor laser amplifiers has been observed with a directly coupled laser-amplifier pair. Amplifier gain as a function of amplifier injection current was measured and compared with theoretical models. Regarding F-P type semiconductor laser amplifier as a photodiode, the optical coupling efficiency between amplifier and laser can be measured by the short photocurrent of laser amplifier.95|69|1更新时间：2020-08-11
- 摘要：A series of uranium(Ⅳ) metaphosphate U(PO3)4 and uranium (Ⅳ) doped thorium metaphosphate crystals Th(PO3)4:U4+ were grown from phosphoric acid solution by the method of solution evaporation.Th(PO3)4 and U(PO3)4 crystal compositions were checked and their crystal structures were determined. Th(PO3)4 and ar-U(PO3)4 belong to triclinic system, P1 or P1-space group.β-U(PO3)4 is orthorhombic system,Cmca-D2h18 space group. The crystallographic data are given. Absorption spectra of U(PO3)4 and the excitation spectra and fluorescence spectra of Th(PO3)4:U4+crystals have been measured at room temperature. Under the excitation with 253nm UV light, U4+ ions doded in Th(PO3)4 matrix emit a series of wide bands of violet fluorescence, which belong to 6d-5f electronic transition of activated U4+ ion. When the crystal is excited by 552nm green light, two narrow bands were found at 358nm and 533nm which might belong to 3P2-3H4 and 1l6-3H4 electronic transitions of U4+respectively. These types of transition can be explained by up-conversion mechanism. The radiation sheme of U4+doped in Th(PO3)4 are given. The fluorescence lifetime of 270nm and 298nm emission of Th(PO3)4 :U4+ crystals is only about ions. This means that the fluorescent emission is responsible for electric dipole transition,121|71|0更新时间：2020-08-11
- 摘要：According to Förster's energy transfer mechanism the energy transfer from acriflavine to 5,10-b.is (P-aminenyl)-l5-20-bispheny]porphin (TBP) and sensitive luminescence of TBP in chloroform solution have been studied by luminescence spectroscopy. The results show that the energy transfer from acriflavine to TBP can be explained simply in terms of Förster's energy transfer mechanism.In the present system we have found that R value of critical trans-fer distance for the donor (acriflavine)-acceptor (TBP) system equals to 0.42nm and the energy transfer effeciency is about 0.72. When the concentration of acceptor increased the lifetime of the donor decreased and the transfer rate increased.The transfer rate given in Table 1 have been calculated from the lifetimes obtained by fitting the date with single exponential decay. From Table i it is clear that the transfer rate is increased from 1.07×107S-1 to 1.42×10S-1.Therefore,it is concluded that in the present system energy transfer from donor to acceptor at this concentration is governed by Förster's energy transfer theory.100|60|2更新时间：2020-08-11
- 摘要：The fluorescence and reflection spectra of ASm2I5 (A=:K,Rb,Cs,Tl) in solid state were studied systematically. The splitting energy(Δ) and f-d excited energy (Efd)of Sm2+ in cubic crystal lattice field are discussed. It is indicated that the increase in r(A+) leads to the decrease in the crystal lattice field effect, and the covalence effect is decreased because of the increase of electronegativity difference between A+ and I-. As a consequence the Efd is reduced. The fact that the fluorescence spectra shift to red or blue among ASm2I5 can be explained by these effects.119|35|1更新时间：2020-08-11
- 摘要：A multi-colour LED flat panel display has been fabricated with 122880 (160×768, matrix) picture elements. The influence of the structure of picture elements on LED flux output efficiency and LED intensity polar distribution is investigated. The mix-colour problem, the hardwares and softwares of the three stages computers used for the display are described.102|55|0更新时间：2020-08-11
- 摘要：Effects of endotoxin-induced lung injury on chemiluminescence(CL) of polymophoneuclear leukocytes (PMNs) are described. In 24 hours after endotoxin injection the peak value of CL of PMNs enhanced markedly though the peak time had no change. Zymosans opsonized by normally pooled plasma and normal self-plasma as well as injuried self-plasma respectively had no effects on CL. The plasma and lung lymph after 2 hours of injury had no activity of promoting CL. These results suggest that a single dose of E. Coli endotoxin should have a strong and lasting effect of activating PMNs and that the Opsonic activity in plasma have no change.114|71|0更新时间：2020-08-11
- 摘要：The study on photoluminescence spectra of GaAs/GaAlAs hetero-NIPI structure is described in this paper. The influence of emission intensity on the transitions among various energy levels is reported. Dependence of emission peaks on the emission intensity is explained by the competition between the neutralization of impurities caused by the injection of photocarriers and the migration of carriers from doped layer to triangular barriers.101|66|0更新时间：2020-08-11
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