Electron transfer induced dissociations of 2- and 4-alkyl cyclohexadienones

Several 2- and 4-alkylcyclohexadienones were prepared and shown to accept electrons to produce ketyl radical anions that dissociated rapidly at room temperature to release carbon-centered radicals and an aromatic phenoxide type anion. In the PET process with benzyl-substituted cyclohexadienones, initiated with triethylamine, the benzyl radicals dimerised or abstracted an H-atom from solvent. In electrochemical reductions, and in reductions with alkali metals in liquid ammonia, the benzyl radicals were further reduced to anions.     

GRIN透镜在细径内窥镜中的应用

介绍在细径内窥镜中ＧＲＩＮ透镜的应用原理及其设计方法。     

一种可实时化的多光谱图像融合系统

在多光谱摄影和光电成像技术基础上，本文提出了一种可实时化的多光谱图像融合系统。与多光谱摄影相比，不仅可实现多光谱实时化摄像，而且光谱响应进一步向近红外延伸，并引入图像处理技术。实验表明：这种技术对于增加系统的识别能力具有明显的作用，可进一步构成不同用途的新型多光谱图像融合系统。     

用反向调制照明法分析光栅成像效应

提出了用反向调制照法明分析光栅成像效应的观点，研究了光栅系统的反向衍射干涉效应，成功地揭示了泰伯效应与劳效应的内在联系，并在白光双光栅衍射干涉的“消色效应”的基础上获得了白光扩展光源照明下白光光栅成像效应和具有实用意义的四光栅干涉系统。     

Crystal structure and magnetic ordering of RNi Si compounds

The element distributions and the magnetic ordering behaviour of compounds RNi₁₀Si₂ (R = Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize in an ordered variant of the ThMn₁₂ structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively, corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn₁₂ structure. TbNi₁₀Si₂ orders antiferromagnetically below T _N = 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi₁₀Si₂ do not carry any ordered magnetic moments. The compounds with R = Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively. Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002     

Temperature Dependence of InSb Reflectivity in the Far Infrared: Determination of the Electron Effective Mass

We measured the dependence of the reflectivity of InSb crystals upon temperature in the submillimeter region using monochromatic radiation from an optically pumped far infrared (FIR) laser. The measures allowed us to determine the value of the electron effective mass at low temperatures with radiations of different frequencies. Our measurements extend the results obtained recently on pure crystals with magneto-optical methods to the low temperatures region where only old measures were available.     

线状锗等离子体X射线线谱的时间分辨测量

用自行研制的X射线条纹晶体谱仪首次测量了线状锗等离子体的X射线时间分辨谱。给出了类Ne-锗L线共振线的时间演化过程,并用类Ne-锗L线共振线与其双电子俘获伴线的相对强度比粗估了锗等离子体的电子温度及其随时间的变化,实验给出了X光激光增益区介质的电子温度为400～760eV,同时给出了电子温度保持相对恒定的时间不小于90ps(电子温度变化小于2％)。     

Determination of electron temperature based on a semicoronal model in Hall accelerator plasma flows

We present the results of a spectroscopic study of a nonequilibrium plasma in a Hall accelerator, in particular for such an important parameter as the electron temperature. For the studied conditions, we used the semicoronal equilibrium model, which relates the intensity ratios for two successive ionization steps for the same element. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 93–96, January–February, 2007.     

中物院远红外自由电子激光实验研究

中国工程物理研究院基于射频直线加速器技术的远红外自由电子激光(FIR-FEL)实验取得阶段性进展,于2005年3月24晚8时30分首次出光, 并多次重复. 中心波长115μm, 谱宽1%.介绍了实验系统的主要组成部分和主要实验结果.     

正电子产生靶上初级电子束半径的最小化研究

为获得尽可能高的正电子(e⁺)产额,严格控制初级电子(e^－)束在e⁺产生靶上的束半径是至关重要的.首先分析了使e^－束半径增大的各因素和对这些因素的制约;然后以北京正负电子对撞机(BEPC)的正电子源为例,给出了束半径的实测值和计算值的比较,以具体说明这些因素的影响;最后讨论了北京正负电子对撞机二期工程(BEPC-Ⅱ)的相应优化设计研究,提出了获得靶上最小束半径的若干途径.