最新刊期
卷 13 ， 期 1 ， 1992
- 摘要：The luminescence properties of Ce3+-and Mn2+-coactivated CaSiO3 have been studied with excitation of both UV light and cathode-ray. In both cases,the red Mn2+ emission is greatly enhanced by Ce3+. The very efficient Ce3+→Mn2+ energy transfer has been investigated by analyzing the optical spactra of Ce3+ and Mn2+ as well as the decay characteristics of Ce3+ luminescence at different Mn2+ concentrations.The energy transfer mechanism has been explored by applying both Förster-Dexter multipolar interaction theory and Inokuti-Hirayama direct energy transfer theory. The results obtained from the two approaches are in very good agreament, which clearly expounds that the efficient energy transfer is the result of cooperative action of electric dipole-dipole and dipole-quadrupole interactions and mainly of the dipole-dipole interaction.126|46|1更新时间：2020-08-11
- 摘要：Diamond-like films were prepared by laser ion beam deposition technique, and the optical absorption, photoluminescence and the dependence of photoluminescence on incident light intensity were measured. Our experimental results indicate that optical gaps vary in the range of 1.67-2.25eV,and the photoluminescance spectrum is a broad band with peak position in the range of visible light. The facts that superlinear luminescence photooxcited by lower incident light intensity and linear luminescencs photoexcited by higher incident light intensity have been explained in terms of the model of nongeminate radiative recombination. Using the model of tail state saturation we also illustrate the fact of blue shift of photoluminescence paak position when increasing the incident light intensity.122|68|0更新时间：2020-08-11
- 摘要：At 77K a peak at 17261cm-1 indicating only one Eu(Ⅲ) ion site in Eu(DBM)32AP (DBM:dibenzoylmethanate, AP:antipyrenc) complex was observed. Spectra of 5DO→7FJ(J=0~4) transitions show that the symmetry for Eu(Ⅲ) site is C2r. The total ligand charge observed was -2.75 which, is in good agreement with the calculated one -3.00.124|47|7更新时间：2020-08-11
- 摘要：As a transform-limited light source, we used a pulsed Rh6G dye laser synchronously pumped by a mode locked Ar+ lasar with, a repetition rate of 82 MHz. The operation wavelength was 514.5nm. The dye laser was tuned to 590 nm which was nearly the peak of the absorption spectrum of cresyl violet in methanol solution. The single mode-locked pulse duration, tp was 3 ps. The output beam of dye laser was split into two beams or the pump beam and the probe beam. The ratio of intensity between them was about 100:1. The light-spot-rodius ratio of the pump beam to the probu was 3:1. It means that the probe beam fell inside the pump beam on the sample. The energy change in the probe boam induced by the pump beam was selectively picked up by a lock-in amplifier.The dynamic equation to describe the absorption racovoiy process can be written as follows dN3(t)/dt=B&(t)N0-N3(t)/τ3 (1) dN2(t)/dt=N3(t)/τ32-N2(t)/τ21 (2) where N0 is the population in the ground state at t= 0. N3(t) and N2(t) arc the transient population in |3 >and|2 >state, respectively. B is a constant relating to the absorption cross suction σ13. Wo resolved eqs. (1) and (2) using N3(0)=N2(0)=0 , then N2(t)∝expτ21) can bo derived. Fitting the experimental data (curve a sea Fig. 4) with those calculated by eq. (3) (curve b), we got the absorption recovery time τ21=162 ps.108|45|0更新时间：2020-08-11
- 摘要：Since Haken had firstly studied the exciton in polar crystals, a lot of scholars discussed the exciton but many of them mainly concentrated their attention on the weak and intermediate coupling cases. In the early 1970's, Huybrechts proposed a linear combination operator method, by which a strong-coupling polaron was studied.S.W.Gu et al discussed the internal motion of strong-coupling exciton in polar "crystal by using the method advanced by Huybrechts. The properties of the exciton in the surface layer of crystals influenca the optical properties of the crystals very remarkably.Most polar crystals are diatomic.In these crystals there is only one mode of longitudinal optical (LO) phonon. The properties of crystals have been studied by a great variety of techniques, in which discussions are limited only for the case of one LO phonon branch. However, a large number of polar crystals, with several atoms per unit cell, have more than one LO phonon branch. For example, in cuprite such as CuO2 there are two LO phonon modes and TiO2, GaAs1-xPx,and, in a large number of perovskites (SrTiO3, LiNbO3....) and quaternary compound semiconductor crystal (AlGaAsSb....) there are more than two modes. In recent years, a lot of scholars investigated the polaron problem of multiple LO phonon branches. However, the exciton in polyatomic polar crystal has not yet been investigated. The ground state energy of the polaron in polyatomic polar crystal is now calculated by using Haga method and the effective Hamiltonian of the exciton in polyatomic polar crystal by means of perturbation method.In this paper, studies on some properties of a strong-coupling surface exciton in polyatomic polar crystals are reported. An effective Hamiltonian of the surfaca exciton is derived by using a linear-combination-operator and Lagrange multiplier method, The renormalized mass of a strong-coupling surface exciton is obtained.In the case of multiple LO phonon branches, the total Hamiltonian of a polyatomic crystal can be written by
We introduce the creation and annihilation operator b+ and b 
and carrying out the unitary transformation 
The ground state wave function of the system is Φ=φ(p)|0> We calculated the effective Hamiltonian and the renormalized mass of surface exciton by variational approach 
.The result indicates that the self-trapping energy and the effective potential of a Wannier exciton can be written as a series in orJ, the first term being proportional to a, the coupling constant. The self-trapping energy and the effective potential not only includes the coupling contribution between the electron-hole and the different LO phonon branches,but also an extra contribution due to crossed terms between the different branches and the different wave vector virtual phonons, which is emitted via the excitonic recoil. The renormalized mass is obtained by Lagrange multiplier method. For Wannier exciton increasing part of the renormalized mass is proportional to a. 107|66|0更新时间：2020-08-11 - 摘要：A simple technique for the preparation of powder compounds MeBeF4 (Me=Ca, Sr, Ba) doped with divalent samarium is described. The samarium impurity is introducad as samarium difluoride SmF2, and the phosphors are synthesized with successive firing of 6 hr in a stream of pure hydrogen in the temperature range of 800-900℃. The data of X-ray diffraction agree with that of references and standard cards. Using this method, samarium has beon stabilized in the divalent state in SrBeF4 and BaBeF4. But in CaBeF4, although in the same synthetic conditions, the emission spectrum of divalent samarium has not been observed either. This indicates that the stability of divalent samarium not only depends on the synthetic conditions but also the composition of the matrix. The data of ESCA indicate that with the increase of the radius of substituted cation, the stability of divalent samarium increases. The emission spectra of Sm2+ and Sm3+ in MeBeF4 are presented and briefly discussed. For the spectra of Sm2+ in SrBeF4 and BaBeF4 its excitation peak is due to the transition absorption of 4f6-4f5d, and the emission peak is due to the transition emission of 5D0-7F7. The transition emission designations of Sm3+ in MeBeF4 are due to4G5/2-8 Hj.107|40|2更新时间：2020-08-11
- 摘要：Based on the kinematical theory of X-ray diffraction, we have calculated the structure factors of X-ray diffraction for strain-layer superlat-tica in this paper. Structure parameters of strain-layer superlattice were succesfully resolved, using the simulation of the calculation.lt is demonstrated that the kinematical theory of X-ray diffraction is available and correct for the calculation of all suparlattices as the dynamical theory of X-ray diffraction. Furthermore, the calculation is simple.113|68|0更新时间：2020-08-11
- 摘要：A new method of studying frequency characteristics of powder EL devices is reported. The method is based on the principles as follows.97|74|0更新时间：2020-08-11
- 摘要：Ga1-xInxAs (x>0.53) may provide the basic of the device (emitter and detector) for the ultralow loss optical fiber communication system. But the Ga1-xInxAs (x>0.53) is lattice-mismatched with InP substrate. And a large number of misfit dislocations will be introduced in epi-layer. So it is difficult to grow high qulity Ga1-xInxAs (x>0.53) on InP substrate.To reduce misfit dislocations, it would be very effective to insert a step-graded composition layer of InAs1-vPr between Ga1-xInxAs and InP.90|25|0更新时间：2020-08-11
- 摘要：The organic emitting material 8-h.ydroxyl quinoline aluminium (Alqs) has bean prepared. The thin film of Alq3 and electroluminescent devices using Alq3 as the emitting element have been fabricated. The photolumi-nescence of this film and electroluminescence properties of the device were investigated. The EL device behaves like an injection-limited model. The device can be driven to produce a green emission with the brightness of 100cd/m2 at a dc voltage less than 30V.109|75|7更新时间：2020-08-11
- 摘要：Two homologous series, ono with a chalcone central linkage (Series Ⅰ) and other the esters of the series Ⅰ (Series Ⅱ) have been synthesised. Three compounds from each series have been inyestigatcd for their luminescent behaviour. All the members of both series show fluorescence. It is observed that the 360 nm emission which is present in series I compounds is absent in the emission spactra for series Ⅱ compounds. However, another emission at 470 nm is observed in compounds of both series. It has bean concluded that hydrogen bond which removes the perturbing effect of the non-bonding electron is responsible for the presence of 360 nm emission in the compounds of Series Ⅰ.109|64|0更新时间：2020-08-11
- 摘要：The generalized-master-cquation(GME) theory of excitation transfer and optical spectra were adopted to investigate the time characteristics of sxciton coherent transport in the molecular aggregates of identical and different chlorophylls for the first time. A coherent time of 200 fs was derived based on its memory function calculation for the transport be-tween chlorophyll a and chlorophyll b, and the results for chlorophyll a and chlorophyll b in solution were 350 fs and 160 fs, respectively. The exciton coherent transport in above aggregates is analysed to be a transfer before vibrational relaxation process. The effects of coherence on excitation transfer and some major factors affecting coherent time are also discussed.120|82|0更新时间：2020-08-11
- 摘要：In this paper,optics and chromaticity characteristics of red(R) ,grcen(G) and blue(B) filters for liquid crystal display are discussed. Fig.3~6 are spectral curves of R,G,B lamp and R,G,B filters respectively.In this report, we have measured values of X and Y of R,G,B filters and obtained sixteen kinds of color triangle region in color coordinates.Optics and chromaticity charateristics are dependent on dye concentrate, pH and temperature of dye sol vents, film thickness and mixture rate of dye.The clear and transparent R,G,B filter can be made because acid dyes are adoptted. Type of dyes,a mixture rate of dye and immersion condition can be controlled so that it is able to obtain different optics and chromaticity characteristics. Results of the experiment show that optics and chromaticity characteristics of R,G and B filter can meet requirements of color liquid crystal display.113|98|0更新时间：2020-08-11
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