最新刊期
卷 12 ， 期 1 ， 1991
- 摘要：ZnS:Mn, Cu powder direct-current electroluminescent(DCEL) devices show wonderful characteristics under alternating-current (AC) voltage operation. The brightness of several tens of foot-1ambert can be obtained easily at no V and 50 Hz, which is two orders of magnitude brighter than that of conventional ZnS:Cu, C1 powder ACEL devices under the same circumstances.This signifies a great achievement in the field of ACEL phosphors.This paper reports the dependences of current-voltage(I-V), brightness-voltage (B-V) and brightness-current (B-I) of DCEL devices as a new kind of ACEL devices. The empirical formulae of above dependences are presented. On the basis of the experimental results, it is confirmed that there are three areas for the load of DCEL devices at AC operation depending on excited conditions. In higher voltage and lower frequency area, DCEL device appears to be a resistive load; in lower voltage and higher frequency area, it appears to be a capacitive load,and between the above mentioned areas, it appears to be a mixed load. The extent of the voltage and frequency for each load area depends on the forming and aging processes. The further forming and aging result in the enhancement of properties of capacitive load and the expansion of all of load areas into high voltage and low frequency area.137|33|2更新时间：2020-08-11
- 摘要：In this paper two-wave coupling in photorefractive KNbO3:Fe crystal is discussed in order to obtain the optimal conditions, under which the two-wave coupling exponential gain r reaches the maximum point.KNbO3:Fe crystal is an important photorefractive material.Its advantages are the fast response time and high sensitivity. The exponential gain r depends both on material propertiess,such as electro-optical tensor components rij and concentration of traps N, and on externally controlled parameters,such as the angle between the two incident beams inside the crystal 2θ, the angle between the grating vector and the crystal optical axis β,etc. We have studied two KNbO3:Fe crystal specimens with N1=1.8×1016cm-8and N2= 1.1×1016cm-3 respectively. And one of them (the second one) is specially cut so that we can obtain β-value near 45° for small 2θvalue.108|58|6更新时间：2020-08-11
- 摘要：were prepared by high temperature solid state action. Their spectral characteristics was studied. It is found that the inhomogeneous line width of Sm2+ emission is dominated by the nearest anion distribution. The 4f5d energy levels of Sm2+ were shifted with varying x or y. The relationship between the emission peak of 5D0-7F0 in BaFCIxBr1-x Sm2+ and x was obtained and analysed. Considering the ratio of in-homogenous line width and other properties, we found that Mg0.5Sr0.6 FCl0.5Br0.5:Sm2+ is suitable for frequency domain optical storge. Its temperature quenching was also studied. Photon-gated spectral hole burning was observed in Mg0.5Sr0.6 FCl0.5Br0.5:Sm2+ and Ba0.5Sr0.5FCl0.5Br0.5:Sm2+ at 77K.102|54|1更新时间：2020-08-11
- 摘要：The research work on the photoemission in CdS crystal was mostly limited in the behavior of bound exciton, excitonic molecule and exciton-exciton (Ex-Ex) interaction at rather lower temperature[1-3]. Saito et al.[3] studied the emission of the near-band edge in CdS within 8-65K. We have investigated exciton-carrier (Ex-e) interaction and the annihilation of a free exciton with emission of a photon and one-LO or two-LO phonons utilizing the photo luminescence (PL) and electroluminescence (EL)[5]. Up to now, there has been no report on Ex-Ex interaction in CdS crystal at the temperature higher than 80K.This paper mainly studies the behavior of Ex-Ex, Ex-e,Ex-1LO and Ex-2LO interaction and the stimulated emission due to Ex-Ex interaction in CdS.The CdS crystal used in this experiment was grown by sublimation method in our laboratory.The PL spectra were measured by Model 44W spectrometer with a RCA C31034 photomultiplier at the excitation of 337.1nm line of a N2 laser in the temperature range of 77K-RT.Fig.112|62|1更新时间：2020-08-11
- 摘要：Study on the perovskite type rare earth gallates is little and there is no report on their spectroscopic properties in the literature. In this work spectroscopic properties of perovskite type LnGaO3(Ln=La,Pr, Nd) and LaGaO3:Ln(Ln=Ce,Srn, Tb) powder were studied at room temperature. The results provide a spectrum basis for new laser or luminescent materials.113|49|2更新时间：2020-08-11
- 摘要：Ce, Tb activated LaPO4(GP) is one of the high effective rare earth green luminescent materials, which has been applied in three basic color fluorescent lamp in the last ten years. In present work, GP has been synthesized, analysed and compared with pratical green phosphor CeMgA111O19;Tb(GA1) on excitation and emission spectra. It can be seen on emission spectra that the 543nm (5D4-7F5) halfwidth of Gp is 3nm smaller than GA1, and its intensity is lower. The intensities for longer wavelengths 584nm (5D4-7F4) and 620nm (5D4-7F3) are stronger than that of GA1, however the y value of which is smaller than GA1 Therefore, in order to get the same color temperature, when GP is selected for the green component, the amount of red phosphor can be deduced.There are some differences in excitation spectra. One is that the measured brightness of GP is 7% higher than GA1 when excited under 254nm. The other is the excitation spectra bands sited after 310nm of Gp are increased, excited intensity of which at 313nm is three times higher than GA1. In addition, intensities of GP at 351, 369 and 377nm are 2-3 times increased than GA1. When rare earth three basic phosphors are used for lamps,the luminescence caused by the secondary mercury lines (313, 365nm) must be considered. According to the relative intensities of 313nm and 365nm line in low pressure mercury lamp and relative excited intensities of 313nm and 365nm in GA1, the brightness increased by 313nm and 365nm excitation is calculated. The increasing factor for GP is about 1%, but for GA1, it is only 0.1%. Thus, it is shown that GP is of more benefit to the increase of luminous flux in lamp fabrication.This paper also deals with the effects of La,Ce proportion on emission and excitation spectra of GP. It is indicated that emission and excitation spectra of GP are all the same when La, Ce proportions are different (La is changed from 0 to 0.58, Ce is varied from 0.8 to 0.22). The above fact means that the function of Ce is not only sentisizer but also a part of host which plays the same role as La. In the case of lack of Ce, the emission spectra of GP still shows the Tb luminescent lines, but the brightness of which is obviously decreased.112|45|2更新时间：2020-08-11
- 摘要：Starting from SSH model and applying the third-order time-dependent perturbation theory, the optical nonlinear susceptibility of one dimensional system has been studied.The effect of electron-lattice coupling on the nonlinear susceptibility is explained. The calculated third harmonic generation of polyacetylene is in good agreement with the measured data,98|65|0更新时间：2020-08-11
- 摘要：The Raman peaks of high performance cis-rich polyacety]ene(HPPA) shift to higher energies as the excitation energy increases. This implies that a shorter chain can be effectively excited by higher excitation energy, and a longer chain can be effectively excited by lower excitation energy. The blue-shift of the dominant peaks in the Raman spectrum of stretched HPPA compared with that of HPPA is observed, indicating the decrease of the interchain distance due to stretching. The luminescence spectra for HPPA and stretched HPPA with various excitation wavelengths are reported.We find that the luminescence spectrum of HPPA shifts to higher energies with the increase of excitation energy, and this blue-shift of the luminescence spectrum decreases with the decrease of the interchain distance. We suggest that there exists the interchain energy transfer in HPPA, which becomes faster as the interchain distance decreases.111|85|0更新时间：2020-08-11
- 摘要：Cytomembrane damage, cell senility and the aging can change the fluidity of biomembrances. The viscosity of cell membrance is increased.In order to study changes of viscosity or fluidity of the cell membrance, we used rat erythrocytes as the source of membrance.Erythrocyte was extracted by Michael's method. After hemolysis the red cell membrancec were washed with buffer and collected by highspeed centrifugation.All cytomembrances were labelled with DPH(1,6-dipheny-1,3, 5-hexatriene, 2×10-6M, 4ml)at 25℃, for 30 minutes and fluorescence polarization was determined with PERKIN-ELMER MPF-66.The results were compared with animal plasma and blood viscosity. We used this fluorescence polarization determination method to study the pharmacological effects of Ginseng on preventing senility and treating arteriosclerosis. The results demonstrate that Ginseng can increase the fluidity(or decrease the viscosity)of red cell membrarce significantly. Ginseng can increase blood flow rates of artificial thrombosis.The experiment fully proved that the method is a practical and effective measure for the researches of pharaceutics.108|45|0更新时间：2020-08-11
- 摘要：Recent years micro-LED assembly has attracted extensive interest for variety of civilian and military applications. The integrating density of light-emitting elements in an assembly becomes higher and higher. Generally speaking, if a common electrode negative or positive is used in the assembly, the micro-assembly will be quite complex. In order to decrease the number of output lines X-Y cross control is adopted. But the problem of electrode isolation must be resolved to realize X-Y control.The problem can be solved in the following way.106|55|0更新时间：2020-08-11
- 摘要：The absorption spectrum and the laser-induced luminescent spectrum of dysprosium-acetylacetone-tri-n-octylphosphine oxide (Dy-AA-TOPO) in the micellar solution of anionic surfactant sodium lauryl sulfo-nate (SLS) were studied using homemade laser fluorimeter. Basic components of experimental apparatus for laser fluorimeter are an actively Q-switched Nd:YAG-pumped dye laser as the excitation light source, a SIT vidicon optical multichannel analyzer as the luminescence detecting equipment and an electric trigger made by our laboratory as the external trigger source. The phosphorescent emission of AA was determined for the first time at room temperature. The luminescence mechanism and a two-step energy transfer process are proposed.The energy transfers from the donor TOPO to the acceptor AA and from the donor AA to the acceptor dysprosium ion. The AA acts both the donor and the acceptor.Dy-AA*-TOPO*-Dy*-AA*-TOPO-Dy*-AA-TOFO+hv-Dy-AA-TOPO+hvThe Dy-AA-TOPO-SLS system is adopted in the determination of the trace dysprosium. The calibration curve is linear over the range of 1-200 ng Dy/ml. A new sensitive fluorescence phenomenon is observed by adding some of metal ions, which is named synergistic luminescence. Results are setisfactory for the determination of dysprosium in highly pure ytterbium oxide and synthetic samples without pre-separation.119|55|1更新时间：2020-08-11
- 摘要：A series of CexGdyTb1-xP5O14 crystals have been grown from phosphoric acid solution by an evaporation method. The structure of crystal belongs to monoclinic system, space group P21/c. The spectra of CexGdyTb1-xP5O14 crystals were investigated. It was found that with the incorporation of Gd to CexGdyTb1-xP5O14 crystal (formed CexGdyTb1-xP5O14) under the same condition a strong emission of Ce3+ reappears,at the same the emission of Tb3+ from 5D4-7F1 becomes much weaker and the emission of Tb3+ from 5D3-7F1 appears. The result is reported for the first time.106|40|6更新时间：2020-08-11
- 摘要：Excitation and fluorescence spectra of SrTiO3:Cr3+ crystal were measured at 63 K and 9 K respectively. The crystal-field energy levels of Cr3+ in SrTiO3 crystal were calculated according to Tanobe-Sugano energy matrices and the experimental results.The sample was grown in reduction atmosphere using melt method, which contains nominally 0.01 Wt.% Cr2O3. A 1-mm-thick, polished sample, which was annealed at 660℃ for one to two minutes in air, was used in the experiment. Annealing the sample in air reduces the oxygen vacancies and increases Cr4+ concentration.The crystal-field strength parameter D9 and Racah parameters B and C obtained were 1626, 471 and 2992cm-1 respectively. The ratio Dq/B=3.46>2.3cm-1 means that SrTiO3 crystal belongs to strong field material. The red shift of R line ralative to other Cr3+-doped crystals is about 100 nm. So large red shift was explained to be due to the strong covalence of the SrTiO3 crystal.120|42|2更新时间：2020-08-11
- 摘要：Single crystals of ZnWO4:Cr3+ with various doping levels have been grown by the Czochralski technique. For this material, the room temperature fluorecence is dominated by the broad band emission extending to 912nm. Excitation peaks drift towards short wave with the incerase of doping concentration.At the emission band the absorbance of ZnWO4: Cr3+ crystal is low. Therefore it may be a tunable laser medium.103|45|3更新时间：2020-08-11
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