最新刊期
卷 9 ， 期 4 ， 1988
- 摘要：The LEPL (Laser excited photo luminescence) spectra of LiYF4:Nd3+, excited by 5145Å emission of an Ar+ Laser, and its XEPL (X-ray excited photo-Luminescence) spectra were bcth studied for the first time. Based on the energy values of the stark levels at corresponding temperatures and referred to their polarization properties, the fluorescence lines were designated (derived from table 1 and table 2). The results are listed in table 3 and table 4.From this work, the foljowing conclusion can be made.(1) Both of LEPL and XEPL in LiYF4:Nd3+ have been studied for the first time,especially.the short wavelength f lucres cence have been observed.(2) The polarization characteristics of LiYF4:Nd3+ fluorescence emission have been studied, and magnetic dipole transitions hava been observed in the system.(3) A new strong fluorescence line (A3→Y3) close to R2→Z1 fluorescence peak has been found in LiYF4:Nd3+.(4) It can be seen from table 3 and table 4, that many fluorescence peaks belong to ax type of spectra. Some Γ5,6T7,8 transitions occur only in particular polarization(σorπ spectrum).For example, the peak 15064cm-1(π, E1(7,8)→X3(5,6)) in table 3 and the peak 26103cm-1(σ,M1(5,6)→Y1(7,8)) in table 4 are these cases. This is the feature of the transitions between kramer doublets.105|39|0更新时间：2020-08-11
- 摘要：RE borate glass is a kind of potentially valuble luminescence material. The luminescence intensities of borate glasses with various concentrations of RE ions (Ce3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+) have been measured.In case of Ce3+, Sm3+, Dy3+. it is found that the emission intensities of glasses decrease if the RE ion concentration exceeds a specific value. It may be explained by cross relaxation for Sm3+ and Dy3+. Sometimes non-radiation losses occur due to interaction between two RE ions, when the Ce3+ concentration increases, the probability of energy transfer exceeds that of emission.The concentration quenching occurs at 1mol% of cerium due to Ce3+-Ce3+ transfer followed by transport to killer sites. However in case of Eu3+, Gd3+, Tb3+, concentration quenching was not found in this work. Maybe their critical quenching concentrations are larger than 3mol%.It was found energy transfer from. Pr3+, Gd3+, Sm3+ to Eu3+ and from Ce3+, Gd3+, Dy3+ to Tb3+. The energy transfer from Gd3+ to Tb3+ and Eu3+ was discussed in detail.Fig.3 shows the excitation spectra of Gd3+ and Tb3+ in doubly and singly doped borate glasses. The excitation spectrum of 312nm emission of Gd3+ in borate glass shows 237nm band which correspond to 8S7/2-6I transition (see Fig. 3-c). The excitation spectrum of 542nm emission of Tb3+ in doubly doped (Tb3++Gd3+) borate glass also consists of 273nm band which is heightened with increase of Gd3+ concentration. This indicates that the excitation energy may be transferred from Gd3+ to Tb3+.The efficiency and probabilities of energy transfer from Gd3+ to Tb3+ was estimate from emission intensities of Gd3++Tb3+ doped borate glass. According to the concentration dependence of energy transfer probabilities,we belive that the interaction between Gd3+ and Tb3+ is dipole-dipole interaction,119|59|0更新时间：2020-08-11
- 摘要：In this paper, we discussed the ultraviolet region of absorption spectrum of Alexandrite (BeAl2O4:Cr3+).The sample we used is grown by the Czochralski method, and its concentration is 0.03wt% Cr2O3.In the absorption spectrum, there are, as we know, two broad bands and a sharp line in visible region, which are the absorptions from ground state 4A2 to 5T1, 4T2 and 2E respectively. In ultraviolet region there are one small peak and two broad bands added to a strong background absorption. We also measured the excitation spectrum in region of 200-700nm at room temperature and confirmed the results of absorption spectrum. The positions of the small peak and two broad bands are about 365, 263 and 213nm respectively.In order to fitting all energy levels, we measured absorption spectrum at low temperature (10.5K), and obtained accurately the energies of 2E, 2T1, 4T2 and 2T2 to ground state 4A2.In the compute of crystal theory, we approximated its symmetry to octahedral symmetry. Using the strong field theory and considered configuration mixing, we fitted the parameters B, C, Dq to four energy levels 2E, 2T1, 4T2 and 2T2. The results are B=778cm-1, C=2967cm-1 ,De=1568cm-1, and mean square deviation is 168cm-1. Then we computed all energy levels. We distinguished the energy levels with same term by Roman numerals.We can get following two conclusions: First, we can consider that the small peak at 365nm is because of the absorption from ground statr 4A2 to excited state 2A1 while the theoret'cal calculation result is at the similar position of 27695cm-1=361nm. Second, the broad band of absorption at 263nm comes mainly from the transition from ground state 4A2 to high 4T1 state [4T1(Ⅱ)], and the transition from 4A2to 2T1(Ⅲ)also fall in this band.100|46|0更新时间：2020-08-11
- 摘要：The luminescence of ZnS and ZnSe doped with rare-earth ions is an interested field[1-6].The reason for this is that,on one hand,the interaction between rare-earth ions and crystal lattice can be understanded by studying the luminescence of rare-earth ions in ZnS and ZnSe crystals, on the other hand, ZnS and ZnSe doped with rare-earth ions are potentially effective materials for colour display.Using ion implantation technique, ZnS and ZnSe diodes have been fabricated and electroluminescence of rare-earth ions have been observed on reverse bias[2,3]. One problem is that the efficiency of these diodes is not so high.108|46|0更新时间：2020-08-11
- 摘要：ZnS is one of the promising materials for blue electroluminescence(EL)at room temperature (RT). In this paper, the thickness of insulating layer(Ⅰ) was measured directly, and the blue EL in ZnS:Ag (or Cu) MIS diodes were obtained at RT, Ag or Cu ions were implanted into low resistivity n-type ZnS dices at RT with the energyrange 70-100keV and the doping range 1-3×l015cm-2. Then the ZnS implanted dices were annealed in N2 flow at 350℃ for 60min. An ohmic contact was made on the non-implanted surface, and a thin Au electrode was evaporated onto the implanted surface in the ZnS dice.124|71|0更新时间：2020-08-11
- 摘要：Zinc-tetraphenylporphyine (ZnTPP) in aerated solution has been examined at room temperature.The fluorescence quenching follows the Stern-Volmer equation as a function of fluorescence intensity or fluorescence lifetime, but a smaller quenching constant Kq, is derived from the fluorescence lifetime as compared with that derived from the fluorescence intensity. This difference seems to be related to the self-absorption in intensity measurement. The experimental results reveal that the quenching constant is related with the solvent viscosity rather than the solvent polarity. This fact appeares to be an indication that this quenching is a dynamic process in nature controlled by diffusion. The analysis of the reaction kinetics shows that this is a strong quenching and the charge transfer quenching rate is larger or approximate to that of the decompsition of the formed complex. The comparison of the experiment results in this paper with the results reported previously by us and others leads us to a conclusion that the solvent effect of charge transfer quenching of excited porphyrin derivatives by quinone compounds is different according to the molecular conditions. The solvent effect on the intramolecular charge transfer and the intermolecular charge transfer accurred in triplet state are mainly due to the solvent polarity, but the intermolecular charge transfer quenching from the excited singlet state is controlled by diffusion and influenced by the viscosity of the solvent.120|64|0更新时间：2020-08-11
- 摘要：In recent years, the optical Instability output characteristics in semiconductor lasers has been studied in a number of optoelectronic devices. As the bistable devices could be used in memory units and optical switching devices. They made a great interest to researchers. However, as far as the optical bistability observed experimentally the optical output hysteresis width is narrow. A narrow hysteresis gives rise to difficulties in controlling switching states, and thus limits the practical applications of optical bistability. Many people currently are seeking ways to fabricate bistable devices with large hysteresis from both experiments and theory. The multi-segment absorptive bistable lasers are one of most important kinds of bistable devices. It is necessary to study this kind of bistable devices and to know its hysteresis width quantitively varying with structure parameters.In this paper, the active-passive tandem ridge waveguide GaAs/GaAlAs laser optical bistable output characteristics have been reported. It includes experimental results as well as its theoretical analysis. Through experiment, it is found that the bistable characteristics are dependent on the length of active region and also the length of passive region. When the length of two segments are in certain proportion, the hysteresis in optical output reaches to a maximum width. The studies on multi-segment laser optical bistability is quantitively reported for the first time. Also, that the current injection level from the third segment in a three section laser has a strong influence to the hysteresis was observed. It is seen that a small abstract current in the third part results in an increase in hysteresis width. These experimental results have the significance in finding laser exhibiting large hysteresis. A ray approximation theory has been applied to our laser, which gives out the rela-tionship between light power and injenction current. However, there is some differences between theoretical calculation and experiment test. The author believes that the differences come from the theoretical equation's invalidity indescribing the scattering loss caused by lateral roughness of ion beam-etching.The loss leads to a very high input level to pump active part and 1o mahethe carrier density high enough in passive part. So, the optical output bi-stability is obtained in a very high injenction current.In our theoretical model, we add a constant optical loss term in the ray equations that is suitable to describe the burid stripe lasers, to simulate the scattering loss in the real case. Neverthless. the scattering loss may not be uniformly distributed. To get a better theoretical model for ridge waveguide absorptive bistable laser, a z-dependent loss term should be introduced. The experimental and theoretical calculation results are shown in Fig.2 and Fig.3. in which experimental optical hysteresis ocurrs at much higher input level than theoretical one does.Summary, the ridge waveguide active-passive segment lasers were tested, the results show that the hysteresis in optical output depends on the length of two segments and this phenomenon was explained theoretically.102|67|0更新时间：2020-08-11
- 摘要：In this report the characteristics of GaAlAs/GaAs Burrus type DH LEDS for the active layer doped by Si or Ge are investigated. The GaAlAs/GaAs DH wafers used for fabrication of the LEDS were grown by LPE technique. The structure of a DH wafer consists of four layers. They are a n-Ga1-xAlxAs buffer layer (x=0.35), a active layer doped by Si or Ge, a Ge doped p-Ga1-xAlxAs confined layer (x=0.35), and a p-GaAs contact layer. The carrier concentration profile of the DH wafer was measured by the electrochemical C-V method. The device output power is about ≥2mW at 100mA.The experimental results are as follows:1. The output power of the GaAlAs/GaAs DH LEDS Si doped active layer are higher than that of Ge doped active layer.2. The cut-off frequence (fc) for the devices of Si doped active layer fc<15MHz at 100mA, for the devices of Ge doped active layer fc>15MHz.3. The emitting spectrum wavelength λ is≥8700Å and 8200Å~8500Å, for the Si doped and Ge doped devices, respectively.4. Using deep level measurement by DLTS and shot transient capacitance it was found that activation energy ΔE=0.29eV and 0.42eV for the Si doped and Ge doped devices respectively.5. The DLTS pattern of the devices for the Si or Ge doped does not show obvious difference.127|39|0更新时间：2020-08-11
- 摘要：A new luminescent material named F F fluorescent film, properties and its applications have been reported.F F fluorescent film consists of daylight fluorescent pigment layer, base, adhesive and anti-adhesive layer.In 1938, G. W. Widmer first synthesized daylight fluorescent pigment. Then the Switzer Brothers gave further development, later daylight fluores-cnet pigment was conceived for commercial production. We have synthesized red-orange daylight fluorescent pigment and made fluorescent film.According to the application requirement,we have studied and measured the properties of F F fluorescent film, including lightfastness, waterproof, adhesive capacity, anti-salt fog and heat resistance etc. It is shown that the properties of our fluorescent film is the same of that, ALKOR, made in FRD.F F fluorescent film is being widely used on advertisements, decorations, danger notices, rescue equipments and traffic signs etc., because of its high visibility and beautiful color. It is attracting the attention of new application in China.131|61|0更新时间：2020-08-11
- 摘要：Using X-ray precession photography method, the stacking fault configu-rations and their probability in single crystal ZnS have been determinated first in present paper[1]. In this paper,some factors affecting precession measurement have been studied and the results are represented as follows.(1) The comparison between the orientafion-photography and the cone-axis-photography to determinate the crystal orientation have been carried out experimently. When the size of cross section in ZnS single crystal is 0.1 to 0.2mm, the orientation-photography is available, while the specimen is very small, the cone-axis-photography will be adoptabie for this purpose.(2) The influences of crystal orientation deviation on intensity distribution on the plane of reciprocal lattice have been studied. When the b axis deviates from the vertical direction in about 1º, the reflection spots en (10·l) row located at zero-level a*c* of the reciprocal lattice are splitted. Whenthe deviation of the b axis is 0.5º, the reflection spots are not splitted butit influences the profile of intensity distribution. While the deviation is 0ºapproximately (about 7' in experiment), where the b axis is almost theprecession axis, the profile of the intensity distribution is symmetric alongc* direction.(3) The influences of time-of-reflection on the intensity distribution of (10·l) row on zero-level a*c* precession photography have been investigated. After Lorentz-polarization correction carried out, the profile of intensity distribution is variated obviously, as a result the values of integrated width of the (10·l) row are affected by Lorentz-polarization correction, which indicates that this correction is necessary in analysis.Other related factors, such as background, overlap, double-spots and absorption effects, which should be noted in the precession photography experiments, are also discussed.101|50|0更新时间：2020-08-11
- 摘要：The "Cross-over" effect is usually observed in the case of DC impulse driving ACEL (alternating current electroluminescence) matrix screen, because of the image-element capacitors crossed-coupling. On a panel of the screen,one picture may be displayed by number ways,but the DC power consumed and picture quality are changed greatly. The most important reason of this behaviors is the crossed coupling of the capacitors. Accurate calcula-tion of the equivalent capacitors and the voltages of image-elements are very important to improve the image quality and reduce the power consumption. This paper gives a new three dimention topology as analogue of the ACEL matrix screen. With the topology, also a plain and strict, way is offered to calculate the equivalent capacitors and the distribution of image-element voltages for ACEL matrix screens.115|60|0更新时间：2020-08-11
- 摘要：Atomic layer epitaxy (ALE) technique developed in. last ten years is actually a novel modification to existing vapor-phase epitaxy methods, such as evaporative deposition, molecular beam epitaxy (MBE), Chloride epitaxy and. metalorganic chemical vapor deposition (MOCVD.). it is based on chemical reactions at the solid surface of a substrate. The compound films with accurate thickness, stoichiometric, high chemical stability, structural perfection and uniform can be obtained by ALE. This review introduces the operation principle, feature and the development of ALE. It was shown that ALE was used to develop successfully large area electroluminescence (EL) thin film displays with excellent characteristics, as well as to grow abrupt heterojunctions, multi-quantum well structure and superlattices in recent years. Thereby, ALE offeres a vehicle for investigating low-dimensional semiconductor thin layer structure.119|189|0更新时间：2020-08-11
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