最新刊期
卷 18 ， 期 1 ， 1997
- 摘要：3P0 to 3F2 fluorescence of Pr3+ in CaS:Pr, Na is studied by means of laser selective excitation. Five Pr centers are revealed. A three-parameter model is used to describe the Hamiltonian of rare earth ions in a cubic lattice with charge compensators. Two of the parameters are B 4 and B 6 of the original cubic crystal, the third is related to the distortion due to introducing the compensator. Fitting the splittings of 3F2 with such a model has shown that the observed centers are Pr3+ with charge compensator situated at different distances.关键词：laser selective excitation;spectra of praseodymium;calcium sulfide;charge compensation108|67|1更新时间：2020-08-11
- 摘要：In this paper we calculate 4A2(S=-3/2)→2E(S=-1/2) photon echo decay induced by Al nuclear spin flip in ruby. Using simple random telegraph model, we investigate Δi which is the variation of Cr resonant frequency caused by each Al nuclear spin(i) flip, and obtain the analytic expression of 〈Ei(t21)〉 through calculating total flip rate W i of Al nuclear(the i th) and Δi. Since the contribute to Cr optical dephasing from each Al nuclear spin flip is approximately independent, the total intensity is the product of 〈 Ei(t21)〉 caused by all Al nuclears. The obtained echo decay can be fitted by I=I0exp〔-(4t/tm)x〕with x, tm values of 2.56, and 50.6 μs which agree with experimental and computer simulated values.关键词：photon echo;ruby;random telegraph process99|72|0更新时间：2020-08-11
- 摘要：Several nanometer luminescent samples——crystal and amorphous——were prepared by sol-gel method. Their structure and optical spectra were measured. Extended X-ray absorption fine structure was used to determine the local environment of luminescent centres of Eu3+ in amorphous nanometer material Y2O3SiO2. It was shown that having the same average coordination number 6.4 and interatomic distances, the local structure of Eu3+ in amorphows nanometer Y2O3-SiO2 was similar to that of Eu3+ in X2 type crystal Y2-SiO5. According to the structure parameter of X2 type Y2SiO5, the crystal field parameter and intensity parameter were calculated using M. F. Reid's model with qL=-0.3,αL=0.2(A3), and so the theoretical spectra of Eu3+ in Y2SiO5 were obtainted. Once the broadening for amorphous was considered, the calculated spectra agreed with the experimental results.关键词：spectrum;nanometer amorphous;Eu3+ ion89|67|1更新时间：2020-08-11
- 摘要：This paper discusses the relaxation processes of exciton in ZnSe thin film and mul tiple quantum wells (MQW's) and the stimulated emission of exciton in narrow-well of MQW's. The nonradiative processes of exciton is the leading facter in the ZnSe thin film. The nonradiative relaxation processes were checked in MQW's. The check effectiveness increases with decreasing well-width. The stimulated emission have been acquired easily in low-dimension material.关键词：quantum well;exciton;relaxation processe;stimulated emission112|75|0更新时间：2020-08-11
- 摘要：The Zn0.8Cd0.2Se-ZnSe strained layer superlattice with waveguide structure was prepared successfully on GaAs substrate by MOCVD. The radiative recombination of n=1 heavy and light hole excitons is observed in photoluminescence spectra at 77 K. The lasing oscillation modes in a F-P cavity with waveguide structure are observed at 77 K under optical pumping operation. It is found that the different modes have different threasholds. The narrower the half width of the time delay curve is, the higher the threashold of the mode.关键词：Zn0.8Cd0.2Se-ZnSe superlattice;exciton luminescence;stimulated emission;time delay curve;threashold90|57|0更新时间：2020-08-11
- 摘要：Distance-dependent fluorescent intensities emitted by europium(Ⅲ) thenoytrifluo roacetonate(EuTTA) molecules separated from Ag, In2O3 and SnO2 interfaces by Al2O3 spacer has been measured. The results show that as the spacer thickness is in range of 1~10 nm, due to the nonradiative energy transfer from the emitting center Eu3+ ions to the dielectric interfaces, the fluorescent intensities vary with the spacer thickness exponentially, and that this is in agreement with the energy flux model.关键词：fluorescent intensity;Eu3+ ion;nonradiative energy transfer;dielectric interface;energy flux model105|80|0更新时间：2020-08-11
- 摘要：There is weak bulk but strong surface coupling between the electron and phonons for polar crystals in a magnetic field. In this paper, the influences of the electron interaction with both the weak-coupling bulk longitudinal optical phonons and the strong coupling surface optical phonons on the properties of the surface magnetopolaron are studied. the cyclotron-resonance frequency and the cyclotron-resonance mass of the surface polaron are derived by using improved linear combination operator method. As an example, the numerical calculation for AgCl crystal has been carried. The results show that the cyclotrou-resonance frequency and the cyclotron-resonance mass of the surface magnetopolaron will be increased with increasing magnetic field.关键词：surface magnetopolaron;cyclotron-resonance frequency;cyclotron-resonance mass99|79|0更新时间：2020-08-11
- 摘要：Adopting a simple method to monitor the outgoing power of Ge-doped optic fiber,the non-stability, saturation, and the non-linear of index disturbance were observed when the fiber was exposed by KrF laser pulses.关键词：KrF excimer laser;Ge-doped optic fiber;index disturbance;non-linear95|65|0更新时间：2020-08-11
- 摘要：The degradation properties of the Organic Thin Film Electroluminescence(OTFEL) devices consisting of a Alq(as a light-emitting layer) and PVK (as a hole transporting layer) were studied under different operating conditions. Under a constant voltage driving and in an ambient temperature, it was found that the brightness, the current density and the lumen efficiency decrease very quickly at the initial step of the degradation process, then turn slow gradually. The trend of the brightness degradation is alike to that of the current density, but the degradation rate is a little larger than the later. It was also showed that when the devices were stored in the air for much longer time the degradation rate of the EL emissions will be accelerated considerably. It is concluded that the phenomenon presumably is due to the effect of the absorbed gases such as the moisture or oxygen gases in atmosphere. The experimental results indicated that the degradation rates of the EL emissions were much slower for the pulse driving than for the continuous DC driving. The degradation differences become more obvious with the fall of the duty ratio. The different degradation rates illustrate that one of the main causes of the brightness decrease is assumed to be Joule heat produced in the device operating.关键词：organic thin film;electroluminescence;degradation property92|89|3更新时间：2020-08-11
- 摘要：Some organic thin film electroluminescent devices with different thickness of 8 hydroxylquinoline aluminum chelate(Alq3) as emission layer, and with different materials such as aluminum doped ZnO(AZO), ITO or for comporison aluminum metal as anode, and with aluminum or alloy Mg:Ag (1:9) as cathode have been fabricated. Their current voltage (J-V) characteristics have been investigated in detail. It could be seen that the current change large with anode material but little with cathode. It indicated that the majourity in current is hole injected from anode. The comparison of quantum efficiency of the devices with different cathode showed that the electron injected from cathode is the minor carrier which determined the electroluminescence efficiency of device. The carrier transport property has been discussed based on the J-V characteristics of the devices with different thickness of Alq3 layer. It is identified that the current in ITO/Alq3/Mg:Ag device is trap limited space charge current.关键词：electroluminescence;organic thin film;carrier injection;carrier transport92|89|2更新时间：2020-08-11
- 摘要：A new chemiluminescence method has been developed for the determination of chlorogenic acid by using the inhibition of chlorogenic acid on the chemiluminescence reaction of Luminol potassium ferricyanide. The method is simple, convenient and sensitive with a detection limit of 5.2×10-9g/ml. It is effective to determine chlorogenic acid in the range of 1×10-8g/ml～1×10-5g/ml. The variation coefficient of eleven determinations for 5×10-7g/ml chlorogenic acid is 1.7%, and recovery is 104%. Furthermore, the inhibition mechanism was discussed in this paper.关键词：chemiluminescence;luminol;potassium ferricyanide;chlorogenic acid111|122|4更新时间：2020-08-11
- 摘要：In the study of large LED panel video display, we always put the main point in the optimization of driving circuit, and seldom care about the visual sensitivity and image quality. This paper, based on human's visual sensitivity, discusses the relationship between large screen video display and the visual sensitivity, and put forward a correction theory. Experiment resultes show that it can supply the same luminance when the columns have the same information and thus quality of image can be improved.关键词：LED;luminance correction;visual sensitivity;constant current drive102|122|0更新时间：2020-08-11
- 摘要：The fabrication of grating coupler and nonlinear waveguide was reported. All-optical switch with ps response time was observed in grating coupling to semiconductor doped glass waveguides.关键词：waveguide;grating;all-optical switch91|114|0更新时间：2020-08-11
- 摘要：ZnS:Mn2+ nanocrystals were dispersed within a PVB polymer matrix to study the effects of size and quantum confinement on the luminescent properties of ZnS:Mn. An increased intensity of the SA emission was observed with the decrease in the size of the ZnS:Mn2+ nanocrystallites. And the emission measurements show a large blue shift of the SA emission peak. RILE effect is also observed and it is stronger than that in ZnS:Mn2+ colloids. It implies that the surface states are more stable in PVB films.关键词：polymer;nanocrystallite;surface modified89|59|3更新时间：2020-08-11
- 摘要：The 50 periods ZnSe0.93Te0.07 (4 nm)-ZnSe(15 nm) multiple quantum wells(MQWs) were grown on (100) GaAs substrate by LP-MOCVD at 450℃. Multiple order satellite peaks in X-ray diffraction spectrum showed the high quality of the MQWs structure. In the PL spectra, stimulated emission was found and we attributed this emission to the selftrapping effect of exciton in type Ⅱ MQWs.关键词：Ⅱ-Ⅵ compound;MQWs;stimulated emission97|46|0更新时间：2020-08-11
- 摘要：LiGaO2 is a new preferred substrate for the eptaxtial growth of GaN visible LEDS and laser diodes. The large-size and high quality single crystals of LiGaO2 up to 15 mm in diameter and 50 mm in length were grown by the Czochralski method. The crystal morphology of all developing facets were investigated.关键词：substrate;LiGaO2113|85|0更新时间：2020-08-11
- 摘要：The waveguide geodesic lens is an elementary components in integrated circuits. Two kinds of effective methods which can be used to measure the corresponding parameters of waveguide geodesic lens are given in this paper.关键词：waveguide geodesic lens;integrated optics99|86|0更新时间：2020-08-11
- 摘要：The valence band spin-splitting for a superlattice composed of AlAs, AlyGa1-yAs, AlxGa1-xAs and GaAs is studied in this paper. It is shown that when the superlattice unit cell is asymmetrcal about the centre of the unit cell, the band corresponding to spin-up and spin-down will spit. The spitting mainly takes place at the stronger interaction. The stronger is the interaction, the larger is the spin-splitting. When y is increased for x being fixed 0.05, the spin-splitting does not cause much variation. However, when x is increased for y being fixed 0.9, the spin-splitting produces a large rise and fall.关键词：energy band structure;superlattice;spin-splitting79|53|0更新时间：2020-08-11
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