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991.
992.
GaAs spin-polarized electron source is a new kind of electron source, where the GaAs semiconductor crystal is used as a photocathode under the irradiation of helicity light. In this paper the activation process of the GaAs spin-polarized electron source is unvestigated experimentally in detail, during which the negative electron affinity of the photo cathode should be achieved more carefully by absorbing the caesium and oxygen on the surface of the GaAs crystal under ultrahigh vacuum conditions. Besides the different activation processes, the important physical parameters are studied to achieve the optimum activation results. At the same time the stability and lifetime of the polarized electron beam are explored for future experiments. Some important experimental data have been acquired. 相似文献
993.
聚乙烯/碳黑导电复合材料的导电性能 总被引:3,自引:0,他引:3
提出并验证了聚乙烯/碳黑(PE/CB)导电复合材料的网络导电性能和产生正温度系数(PTC)特性的原因,分析了加工过程、温度和辐射交联等后处理过程对其导电性能的影响. 相似文献
994.
A cylindrical capacitor containing rubidium vapour is made. The capacitance of it at different voltages is measured under a certain Rb vapour pressure. The experimental C-V curve shows that the saturation polarization of Rb vapour is easily observed. The experiment further supports the idea that the Rb atom has a large permanent electric dipole moment. 相似文献
995.
The evolution of sum-chirp for an initially chirped Gaussian pulse is studied in the polarization multiplexed communication system, with fibre attenuation considered. The sum-chirp is found to have the character of saturation.Its value appears different along the two different polarization axes, determined by the incidence polarization angle. We also find that sum-chirp is dominated by the initial chirp at a short distance, and by the cross-phase modulation effect at long distance. And it is influenced apparently by a wavevector mismatch parameter below 10ps/km. Further, its saturation results from the effective distance determined by fibre attenuation. 相似文献
996.
ZHANGCai-rong CHENHong-shan WANGGuang-hou 《高等学校化学研究》2004,20(5):640-646
The possible geometrical structures and relative stabilities of semiconductor microclusters Ga.P.(n=1-4) were studied by virtue of density functional calculations with generalized gradient approximation(B3LYP). For the most stable isomers of Ga,,P.(n=1-4) clusters, the electronic structure, vibrational properties. dipole moment, polarizability and ionization potential were analyzed by means of HF. MP2. CISD and B3L YP methods with different basis sets. 相似文献
997.
光栅摄谱仪的改进及其在周期性极化的铌酸锂晶体倍频研究中的应用 总被引:1,自引:1,他引:0
由于电荷耦合器件(CCD)具有光谱响应范围宽、检出限低、动态范围宽、暗电流和读出噪声低以及具有积分信号、多道同时检测和实时检测等能力的优点,在光谱测量和光谱成象领域获得了广泛的应用。将传统的1m光栅摄谱仪和科学CCD相结合,使其具有实时快速测量激光光谱的能力。将其应用于宽带双包层光纤激光在周期性极化的LiNbO3晶体(PPLN)中倍频特性的研究,观察到了倍频激光光谱随PPLN控制温度的动态变化过程,并对此进行了详细分析。 相似文献
998.
999.
巨磁阻Mn氧化物中小极化子的直接观察 总被引:1,自引:0,他引:1
巨磁阻系列材料La(Ca)MnO3和Pr(Ca)MnO3在低温下进入电荷有序态。利用低温电子显微镜观察,对定域化载流子(空穴)引起的结构转变进行了特征化,发现了一系列复杂的微结构现象。特别重要的是,在低温下出现的一个调制结构,它表现出一些奇特的温度变化性质。进一步分析表明,这个调制结构和小极化子有序化状态相结应。 相似文献
1000.
This letter describes a method for calculating water-leaving radiance on smooth surfaces at differentangles based on Fresnel law and the polarized measurements using an ASD FS3 spectroradiometer. The spectroradiometer is mounted on a goniometer so that it views the water surface from a height of severaldecimeters at different viewing angles through a linear polarizing filter. The incident angles equal theviewing angles. The water-leaving radiance spectra acquired by other methods are compared with the polarized measurements from the smooth water surface, and the radiance spectra obtained by the proposedmethod are found to be consistent with the results of the reference methods. The current study provides another effective technique for measuring water-surface reflectance via remote sensing. Moreover, the method does not avoid the sun glint during the detection of water-leaving radiance in cases where the viewing geometric position is clear. 相似文献