Photoluminescence linewidth broadening due to alloy/thickness fluctuation of CdxZn1 − xSe/ZnSe triple quantum wells

Photoluminescence (PL) linewidth broadening of Cd_xZn_{1 − x}Se/ZnSe triple quantum wells, grown on GaAs substrates by molecular beam epitaxy (MBE), has been investigated. Various quantum well (QW) samples have been prepared with different QW thickness and composition (Cd-composition). Measured and calculated PL linewidth are compared. Both composition and thickness fluctuations are considered for the calculation with the parameters such as the volume of exciton, nominal thickness and composition of QWs. Surface roughness measured by atomic force microscopy (AFM) is used to estimate the interface roughness. Results show that when Cd-composition increases additional linewidth broadening due to Zn/Cd interdiffusion is enhanced.     

电子束驱动的回旋激射不稳定性

对弱相对论性电子束驱动的回旋激射(maser)不稳定性的一般理论作了详细讨论.对在获得增长率实用表达式过程中若干解析表达式的推导与细节做了仔细的补充讨论和说明，还增加了增长率的近似表达式，并由此得到了回旋激射不稳定性主要特征的解析分析以及与精确计算的比较，使整个理论有一个完整的描述.侧重解析讨论，也提供了部分一般性的数值计算结果. 关键词： 回旋激射不稳定性 弱相对论性电子束 增长率     

连续激光诱导Zn/InP掺杂过程中温度分布的解析计算

在实验的基础上，分析表面蒸发Zn的InP样品在连续激光诱导下掺杂Zn过程.在一维热传导问题的第三类边界条件下，给出激光辐照有限厚双层材料Zn/InP温度分布的一种直观简洁的解析形式. 关键词： 激光诱导掺杂 Zn/InP 温度分布     

相对论重离子碰撞实验中混合事件方法的研究

把RQMD(Relativistic Quantum Molecular Dynamics)产生器产生的数据输入作为原始事例取样,讨论了在比较复杂的背景情况下,一种新的混合事件方法,用以证实在相对论重离子碰撞实验中高能量激发共振态的存在.并以共振态重子Δ⁺⁺为例演示了这一方法的应用.     

CONVERGENCE OF CASCADE ALGORITHMS AND SMOOTHNESS OF REFINABLE DISTRIBUTIONS

In this paper, the author at first develops a method to study convergence of the cascade algorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), and then applies the previous result on the convergence to characterizing compactly supported refinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems 3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriate initial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).     

全内反射荧光显微术应用于单分子荧光的纵向成像

利用这种显微术中激发场的纵向强度呈指数衰减的分布特性，测得的荧光强 度将强烈依赖渗透深度（强度衰减到1/e时的距离），从而快速直接的确定单分子荧光 团间的纵向间隔、每个荧光团的纵向绝对位置和荧光团的半径大小，即实现荧光分子三维分 布的重构.在整个重构的过程中，只需要改变一次入射角的大小，即只需探测两幅荧光分子 的全内反射成像. 关键词： 全内反射荧光显微术 纵向重构     

Investigations of low- and high-spin states of <Superscript>132</Superscript>La

The fusion evaporation reaction ¹²²Sn(¹⁴N, 4n)¹³²La was used to populate the high-spin states of ¹³²La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2^- and the isomeric state 6^-. A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh _11/2 ⊗ νh _11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies in the spin assignment of the band head. Received: 12 August 2002 / Accepted: 18 March 2003 / Published online: 7 May 2003     

Cu~+、Ag~+、Au~+与乙硫醇的气相化学反应

利用激光溅射 分子束的技术 ,结合反射飞行时间质谱计 ,研究了Cu+、Ag+、Au+与乙硫醇的气相化学反应。结果显示这三种金属离子与 (CH3 CH2 SH) n 反应形成一系列团簇离子M+(CH3 CH2 SH) n,且团簇离子尺寸不一样。Ag+、Au+与乙硫醇的反应还生成了 (CH3 CH2 SH) +n ,由此推测Cu+、Ag+、Au+与乙硫醇团簇的反应存在两种通道 ,一种通道是生成M+(CH3 CH2 SH) n,另一种是生成 (CH3 CH2 SH) +n 。Cu+、Au+与乙硫醇的反应还生成了M+(H2 S) (M =Cu、Au) ,但是实验中没有观察到Ag+(H2 S) ,理论计算表明Ag+(H2 S)很不稳定。另外 ,分析产物离子M+(CH3 CH2 SH) n 的强度发现 ,n =1～ 2之间存在明显的强度突变现象     

Magnetic poly(N‐isopropylacrylamide) microspheres by dispersion and inverse emulsion polymerization

The aim of this study was to develop novel thermally responsive polymer microspheres with magnetic properties. Dispersion and inverse emulsion copolymerization of N‐isopropylacrylamide (NIPAAm) and N,N′‐methylenebisacrylamide (MBAAm) was investigated in the presence of γ‐Fe₂O₃ nanoparticles. The resulting microspheres were characterized in terms of morphology, size, polydispersity, iron content, and temperature‐dependent swelling using optical microscopy, transmission electron microscopy, scanning electron microscopy, QELS, and AAS. The effects of several variables, such as the concentration of γ‐Fe₂O₃, MBAAm crosslinking agent, Span 80 surfactant, 2,2′‐azobis(2‐methyloctanenitrile) (AMON) initiator, and polymerization temperature on the properties of the microspheres were studied. Swelling and thermoresponsive behavior of the microspheres containing γ‐Fe₂O₃ nanoparticles were also investigated. The microspheres contained about 8 wt % of iron. The presence of magnetic nanoparticles and their concentration changes did not have any significant effect on the temperature sensitivity of the composites. The particles gradually shrink into an increasingly collapsed state when the temperature is raised to 40 °C since the increase in temperature weakens the hydration and PNIPAAm chains gradually become more hydrophobic, which leads to the collapse of the particles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5884–5898, 2007     

基于实数编码的免疫遗传算法研究

针对标准遗传算法(SGA)搜索效率低、收敛速度慢等缺陷，在免疫遗传算法的基础上提出了基于实数编码的免疫遗传算法(RIGA)。研究表明，RIGA对SGA的改进是有效可行的，显示出稳健的全局优化、计算量少而解的精度高等特点，具有较高的应用价值。