高能电子和正电子在晶体沟道中的辐射

介绍了高能电子和正电子在晶体中的沟道辐射,对超相对论电子和正电子在周期弯曲晶体中的相干辐射进行了分析,并提出了初步的实验设想. The channeling radiation of high energy electrons and positrons in crystals was introduced. According to the new idea proposed by A.V.Korol, the coherent radiation of ultra relativistic electrons and positrons channeled in periodically bent crystals was analyzed. The characteristics of the radiation were obtained by using classic electromagnetic theory and a tentative experimental plan for testing was suggested.     

Low-Threshold Mid-Infrared Optical Parametric Oscillator Using Periodically Poled LiNbO33

We report the generation of tunable mid-infrared optical pulses using all-solid-state pumped optical parametri coscillator in a periodically poled lithium niobate. Several ways were used to lower the threshold, resulting in a mean threshold as low as 6.5mW and an achievement of wavelength conversion in the 2.77-4.04μm spectral range. Continuous tuning range from 2.97 to 3.25μm was achieved. The maximum idler output power of 466mW at the wavelength of 3.41μm was obtained, which represents an optical-to-optical conversion efficiency of 19% from incident pump power to the idler output.     

Measurement and Analysis of Composition and Depth Profile of H in Amorphous Si1-xCx:H Films

Composition in amorphous Si1-xCx：H heteroepitaxial thin films on Si （100） by plasma enhanced chemical vapour deposition （PECVD） is analysed. The unknown x （0.45-3.57） and the depth profile of hydrogen in the thin films are characterized by Rutherford backscattering spectrum （RBS）, resonance-nuclear reaction analysis （R-NRA） and elastic recoil detection （ERD）, respectively. In addition, the depth profile of hydrogen in the unannealed thin films is compared to that of the annealed thin films with rapid thermal annealing （RTA） or laser spike annealing （LSA） in nitrogen atmosphere. The results indicate that the stoichiometric amorphous SiC can be produced by PECVD when the ratio of CH4/SiH4 is approximately equal to 25. The content of hydrogen decreases suddenly from 35% to 1% after 1150℃ annealing. RTA can reduce hydrogen in SiC films effectively than LSA.     

肿瘤细胞内CdS纳米量子点的仿生化合成

以宫颈癌HeLa细胞为载体,细胞内源性谷胱甘肽为保护剂和稳定剂,在细胞生命代谢活动驱动下合成性质优良的CdS量子点。光学性能表征显示,该CdS量子点在波长为450nm左右有发射峰,其荧光产率为5.2%。透射电镜表征显示CdS量子点粒径约为3.0nm,X射线衍射光谱表明该CdS量子点为立方晶型结构。     

求解含缺陷一维周期结构动力响应的高效算法

基于周期结构的动力特性和群理论,建立了一种高效求解含缺陷一维周期结构动力响应的数值方法。在求解结构动力响应时,高效求解结构对应的线性代数方程组最为关键。采用凝聚技术,可减小结构对应线性代数方程组的规模。基于周期结构动力系统中线性代数方程组的特性,通过一个小规模含缺陷结构和一维周期结构的响应分析,可得到含缺陷一维周期结构的动力响应。同理,一维周期结构的动力响应可通过一系列小规模结构的响应分析得到,且小规模结构的动力响应可基于群理论高效求解。数值算例表明,本文算法有较高的求解效率。     

基于冷原子吸收分光光度法的热解析-低温等离子体脱汞技术研究

研究含汞土壤的修复问题,采用热解析和低温等离子体综合技术探究新途径,调整温度、添加剂、时间等因素来判断脱汞效果并探究其不同形态,分析工艺过程废料的内部联系,并对废气处理进行分析实验。结论如下：(1)通过改良技术的BCR连续萃取法,得出研究区汞的形态主要为有机结合态(53%)。之后依次是氧化物结合态(33%)、酸可提取态(8%)、残渣态(6%)。(2)温度对热解析程度影响较大。在500℃以上的热解析条件下,土壤中的汞浓度不足1.5 mg·kg-1。(3)当选用400℃的解析温度时,40 min汞去除总体完成。在低于1 700 mg·kg-1的浓度下,汞去除率随着土壤中的含量的增大而减小。(4)氯化钙对于热解析的促进作用最强,柠檬酸、升华硫也有一定作用,硫化钠对于汞去除形成阻滞。(5)低温等离子体的最佳状态是电源设置电压为22 kV,频率为660 Hz。整个系统的汞去除程度可达近90%。     

轴流式射频PCVD沉积质量分布的动力学分析

在用静电探针诊断了轴流式射频等离子体激活化学汽相沉积(PCVD)反应器中等离子体电子温度、电子密度轴向分布的基础上,提出与主要工艺参数相联系的二元流体动力学模型。以等离子体参量的轴向分布和变化规律为中介量,从动力学的角度分析主要工艺参数影响PCVD沉积质量分布的规律。将模型用于沉积SnO₂薄膜的过程,理论计算与实验结果符合较好。 关键词：     

对初中电压教学问题的商榷

初中物理课本下册(1956年4月版本)中对电压概念的叙述,和以前几版一样,在实践中仍感到难于被学生所接受。我们认为教材似有下列几个缺点。 1.电压这个概念的叙述方式和以前各概念的叙述方式不协调,以致有的学生感到困难。课本中在这以前对各个物理量一般的表达方式如:     

CCl自由基A 2Δ←X 2Ⅱ跃迁REMPI光谱研究

在271～279 nm波长范围内采用REMPI技术研究CCl自由基的A 2Δ光谱.实验观察到12C35Cl以及同位素分子12C37Cl 的A 2Δ←X 2Ⅱ1/2,0-0,1-0和2-1跃迁谱带,其中2-1的跃迁为新观察到谱带.获得了A 2Δ←X 2Ⅱ1/2电子跃迁0-0,1-0,2-1谱带的同位素位移.     

Charge Transport and Magnetotransport Properties of Polyimide Irradiated by 80keV Co Ions

Charge transport properties of polyimide films implanted with 80 keV Co ions at two different fluences （series I： 1.25 × 10^17 ions/cm^2, series Ⅱ： 1.75 × 10^17 ions/cm^2） are studied in detail. For series I, the temperature dependence of surface resistivity fits Mott＇s equation very well. It is on the insulating side of the insulator-metal transition （IMT）. However, for series Ⅱ, the temperature dependence of surface resistivity is not in agreement with Mott＇s equation. It is on the metallic side of lMT. The magnetotransport properties of these two series are also studied. No significant magnetoresistive effect is observed for series I at both 5 K and 300 K. For series Ⅱ, an obvious magnetoresistive effect is observed at 5 K, while there is no magnetoresistive effect at 300 K. Rutherford backscattering spectrometry （RBS） is applied to confirm the actual fluence for these two series.