最新刊期
卷 9 ， 期 2 ， 1988
- 摘要：In this paper we present a linear variational calcularion of the lower lying states of rhe electron-hole system confined in three-dimensional quantum wells with spherical shape.Because the total argular momentum L=-ir1×▽1-ir2×▽2 of rhe electron hole system in the sphere commutes with the Harmitonian, we choose the eigenfunction of L2 and L2 as the basis funcrion, which is given by Eq. (5). In (5),|n1l1m1〉 and |n2l2m2〉 are the eigenfuctions of argular-momentums of the electron and the hole respectively, which are given by Eq. (6) and Eq. (7). The matrix elements of rhe Harmiltonian (2) in this base are calculated with the formula (10) and (11). The matrix of H is divide into submatrixes. The basis funcrions with the same L and ML are atribured to the same submatrix.94|47|0更新时间：2020-08-11
- 摘要：Recently, it has been shown that quantum sizs effects may be observed at low temperature in comercial optical glass filters.It is also reported that small crystallites of CdS are synthesized via colloidal chemical techniques,and their optical properties as a function cf crystallite size are studied at extreme dilution. This is a new type of quantum well heterstructures. Unlike layered heterstures,in which there is confinement in only one dimension, they are, in space, confined in all three dimensions.The optical properties of a micro-crystallites embeded in another dielectric strongly depend on the thermal vibration of the crystal. The presence of the crystal boundary leads specific surface vibration of the crystal. These vibration are localized near the boundary. Thermal excitation of surface vibrations is also accompanied by the occurrence of alternating dipole moments and, therefore, cf an electromagnetic field. The present paper deals with the theoretical investigation of the bulk and surface vibrational states for a microcrystallites embeded in another dielectric. It is an important problem for understanding the optical phonomena occurred in these new types of heterstructures.In the sixties, a phenomenological describtion of the vibrational states for any shaped dielectric imbeded in another dielectric had been given by Englman and Ruppin. However, they did not consider the influence of the electronic polarizability. Recently, Wendler and Pen Jinsheng deduced the equations of motion for the polarization eigenmode of the dielectrie bilayer system from the microscopic dynamical equations. Here we shall extend these results to discuss the vibration states of a dielectric sphere or other shaped crystallites embeded in another polar or non-polar dielectric.of course, the influence of the electronic polarizability is also taken into consideration.103|59|0更新时间：2020-08-11
- 摘要：In this paper, the surface phonon modes of CdSxSe1-x micro-crystals in glass medium were observed by means of Raman scattering.When a different ratio of CdS powder to CdSe powder is introduced to a milticomponent silicate glass medium through the heat treatments. The average size of the microcrystals will increase with the increase in the heat treatment time. In this note, two kinds of sample are used. One is called series A, in which x=0.95; the other is called series B, in which x=0.98.Fig. 1 is the Raman spectrum of sample A2, in which there are five Raman peaks. Their position are 199, 299, 309, 507, 614(cm-1), respectively.103|45|0更新时间：2020-08-11
- 摘要：When cyanine dye with long chain hydrocarbon octadecane form mono-layer at air-water interface, the long axes of chromcphore all lie in the layer while the short axes stand perpendicular to it.Under certain pressure, the long axes of near neighbors are usually parallel and closely to some extent forming a strure so called J-aggregates.The structure cf J-aggregates is such that the dipole of the dye can coupled together so the molecular exciton theory of Davydov for weakly coupled composite systems can be used.According to this theory, the energy transfer in such systems is the rapid, long range exciton transfer.To study the energy transfer inside the Langmuir-Blodgett monolayer, we prepare the monolayer by standard L-B technique, i.e., mixing proper molar ratio of dye Ⅰ and dye Ⅰ and adding sufficient quantity of hexadecane so that dye 1+dye Ⅱ: hexadecane=1:1. The fluorescence spectrum of dye I and the absorption spectrum of dye Ⅱ overlap partially, providing the possibility for energy transfer from excited dye Ⅰ to dye Ⅱ. It is well known, that there are various types cf energy transfer between molecules.In our case, Forster transfer and exciton transfer are considered.88|80|0更新时间：2020-08-11
- 摘要：A new kind of multi-layer structure has been used to prepare the SrS:Ce3+ thin film ACEL devices. The different between this device and conventional ZnS device is that there is a thin layer of pure ZnS,as a barrier layer, sandwiched between the Y2O3 dielectric layer and the SrS:Ce3+ active layer. The SrS phosphor layer was deposited by electron beam evaporation at higher substrate temperature of 350℃.X-ray diffraction analysis indicates that a high degree of crystalline perfection was formed at this temperature. The saturated luminescence brightness observed for SrS:CeCl3 TFEL devices was about 100cd/m2 under 5kHz AC excitation.98|41|0更新时间：2020-08-11
- 摘要：Some recent research on ac-coupled thin film EL devices has been aimed at solving the problem of multicoloring.For multicoloring, rare-earth ions, which offer a wide variety of emission wavelength in the visible spectrum, have been widely investigated mainly in ZnS thin film. ZnS doped with ErF3 is an important green EL material, So far, no detailed study on the influence of ErF3 concentration on EL characteristics in ZnS:ErF3 EL thin film.90|31|0更新时间：2020-08-11
- 摘要：The properties of multilayer structure or superlattices consisting of alternating layers of amorphous semiconductors have aroused considerable interest during the last few years. By plasma deposition and by alternating the plasma-gas mixture, we prepared multilayer films consisting of sequential layer of hydrogenated amorphous silicon (a-Si:H) and insulating amorphous silicon nitride (a-SiNx:H).The photolumenescence measurements have been carried out for the structure above. The experiments show that the energy (Ep) of the photolumenescence peak increases by 0.10eV and broadens 0.20eV as a-Si:H layer thickness is decreased from 105Å to 15Å. This is tentatively attributed to quantum size effects and two-demensional confinement in the thin a-Si:H layer. We also find striking the temperature dependence of the photoluminescence spectra. In bulk a-Si:H, the large temperature coefficient of Ep is usually due to thermolization down tail states based on short range disorder. We observed for all our multilayers films a photoluminescence fatigue of 10% after an exposure at 77K to 5×1021/cm2·s photons of hv=2.40eV for 30min. The photoluminescence measurements indicate that the photoluminescence spectra of anade sample is different from that of cathode sample. These results have been interpred in terms of the bonded hydrogen content in the a-Si:H layers.90|42|0更新时间：2020-08-11
- 摘要：The emission spectra of Nd0.9La0.1P5O14 (NLPP) crystal have been measured at 40K(see Fig.1).We found four series emission lines: at~0.9μm due to 4F3/2-4I9/2 transitions of Nd3+ ions, ~l.05μm due to 4F3/2-4I11/2 transitions, and~1.35μm to 4F3/2-4I13/2 transitions.The lines at~1.8μm have been proved to be the second order diffraction of the 4F3/2-4I9/2 transitions, although the lines of 4F3/2-4I15/2 might be expected to occur in this region.113|48|0更新时间：2020-08-11
- 摘要：When the pulse-fluorescence method is used to measure molecular fluorescence-lifetime, and if it is near to or smaller than the instrumental response time, the observed fluorescence decay curve is a convolution of the true fluorescence decay curve and the instrumental response function. That is, if the true fluorescence decay curve is G(t) and the instrumental response function is F(t), then the observed fluorescence decay curce will be D(t)=∫0tG(t′)F(t-t′)dt′.Therefore, it needs to carry out deconvolution proceeding for obtaining the true fluorescennce decay curve. In deconvolution method. the calculation is very strenuous and its result is dependent on the accuracy in measuring the instrumental response function:a small deviation of F(t) may produce a iserious deviation or wrong result for calculating fluorescence lifetime.117|81|0更新时间：2020-08-11
- 摘要：In this paper, the selective excitation emission spectra, excitation spectra,luminescence decay,diffuse reflection spectra and EPR spectra of Ce-Mn activated calcium fluorophosphate are measured and analysed,two sort of Ce luminescence centers are first discovered and their situation are suggested, the energy transfer from Ce centers to Mn centers is studied.Two series of Ce3+ emission spectra have been observed by means of selective excitation. One is double peak structure with the main emission peak at 332nm when the sample is excited at 254nm, the other is also double peaks structure with the main peak at 332nm when the sample is excited at 337nm. It is affirmed by analysing these spectra that the double peaks structure originate from the 5d-2F7/2 and 5d-2F5/2 transitions of Ce respectively. And the two series structure come from two kinds of luminescence centers(labslled Ce Ⅰ and Ce Ⅱ). Comparing the excitation spectra of Ce Ⅰ and Ce Ⅱ with the absorption spectra of FAP:Ce, it can be found that of Ce formed Ce Ⅰ centers.107|56|0更新时间：2020-08-11
- 摘要：The change of deep level for p+-nGaP:N LED's during degradation was investigated by DLTS techniques. Its. degradation condition is J=200A/cm2 and t=650 hours at room temperature. And their luminescence spectra, luminous fluxs, C-V characteristics, EBIC, CLI AND SEI were measured.The parameters of deep level before and after degradation were listed in Table 1.110|87|0更新时间：2020-08-11
- 摘要：GaAs-GaAlAs light emitting diodes (LEDs) have been fabricated and applied to optical fiber communication system by the authors. The various nonlinear P-I characteristics from the LEDs have been found. The reasons of causing the nonlinear P-I characteristics and the effect on optical signal distortions from them have deeply been discussed The methods for solving nonlinear distortions have been presented. Nonlinear distortions in LEDs are due to effects of the carrier injection level,radiative recombination,and other subsidiary mechanisms.110|64|0更新时间：2020-08-11
- 摘要：The plastic optical fiber system is now the most economic and most competing optical transmission systems in distances within 50M.The core of the fiber is 1mm and it is easy to couple and low in price.The development of quartz optical fiber systems is very raped. Many research works are devoted to the temperature dependence of light source devices of the system and a lot of schemes are developed to keep the light output constant at different temperatures, as the light feedback method, but this is a relatively expensive method in price.The plastic fiber system use low cost superradiant LED and infrared LED, But it's temperature characteristics and temperature compensation method are not commonly at hand. So it is necessary to study the temperature characteristics and compensation methods specially suitable to LED for he plastic optical systems. This paper studied the temperature characteristics and compensation methods of GaAlAs superradiance LED and GaAs infrared LED. It is pointed out that the GaAlAs superradiance LED is superior to the GaAs infrared LED in temperature, characteristics, life time and frequency response. Especially in temperature characteristics,the former is notably better than the latter. So, for the plastic optical fiber systems, the GaAlAs super radiance LED is recommended.In this paper, we use the silicon diodes with a negative temperature coefficient as the compensating element. Two experimental circuits are used and analysed. It is noteworthy that for GaAlAs superradiance LED and GaAs LED in temperature ranges of 5℃-60℃ the results are.1. The power level variation 2.2% the current change is 1.8mA. 2. the power level variation 3%, the current change is 0.8mA.So the methods recommended in this paper are both suitable for plasjc fiber optical system and for optical fiber sensor systems.98|73|0更新时间：2020-08-11
- 摘要：In this paper, we present a theory of fluorescence quenching of adsorbed molecules on metal or semiconductor surface.We propose that the fluorescence quenching is due to energy transfering from adsorbed molecules to forced plasmon.151|57|0更新时间：2020-08-11
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