半绝缘GaAs光电导开关的超线性时间响应分析

报道了用1064nm激光脉冲触发电极间隙为3mm的横向半绝缘GaAs 光导开关的实验结果.对半绝缘GaAs光电导开关的超线性时间响应特性做了分析,表明半绝缘GaAs材料EL2能级对电子和空穴的俘获截面有较大的差异,这种较大的差异造成开关对激光脉冲的超快响应.     

基于平行投影法的三维流场重建

在行处理方法的基础上提出了一种基于平行投影的迭代方法，对传统的行处理方法不同，它不是通过向某一超平面作垂线进行迭代，而是作某个超平面的平行线与另一超平面相交进行迭代。与传统方法相比，它明显加快了迭代速度。     

Single-mode rib polymer waveguides and electro-optic polymer waveguide switches

Mode-matching and effective index methods are used to analyze single-mode operation of optical rib polymer waveguides. Their single-mode waveguiding conditions are determined. Single-mode rib waveguides fabricated from guest–host polyetherketone are presented. The estimated propagation loss of straight rib-waveguides is 0.7 dB/cm at 1.55 μm. Furthermore, by using the mode field-transfer matrix method, 2×2 and 4×4 polymer Mach–Zehnder interference switch operating at 1.55 μm wavelength has been designed based on optical multi-mode interference.     

掺Eu3+硅基材料的发光性质

通过溶胶－凝胶技术制备了掺Eu^3 的硅基材料并测试了其三维荧光光谱、激光谱和发射光谱，结果显示，最佳激发波波长为350nm,最强荧光波长为620nm；在350nm光激发下的发射光谱显示Eu^3 的特征发射光谱，产生4条谱带，分别是577nm(^5D0-^7F0)，588nm(^5D0-^7F1),596nm(^5D0-^7F1)和610nm(^5D0-^7F2)。     

双水相体系中镧与钛的分离及光谱性能

在聚乙二醇-硫酸铵-铬天青S双水相体系中，用铬天青S作萃取剂，研究了La(Ⅲ），Ti(Ⅳ），Zr（Ⅳ）的液-液萃取行为，在pH5.5时，实现了体系中La(Ⅲ）与Ti(Ⅳ)的分离，通过加入表面活性剂测定光谱方法，研究了高聚物相中La(Ⅲ）的存在形态。     

利用激光干涉测钢丝的杨氏弹性模量

分析了在洛埃镜干涉装置中等效双狭缝间距变化对干涉条纹密度的影响。导出了钢丝因受力引起的绝对伸长量与干涉条纹密度变化之间的关系 ,并通过它计算了钢丝的杨氏弹性模量。结果表明 ,激光干涉法不仅比光杠杆法测量的量要少 ,而且用该方法通过测微目镜测条纹的位置要比光杠杆法通过望远镜对标尺读数精确 ,其测量结果要比光杠杆法更准确可靠     

开设实验选修课培养学生创新能力

介绍了复旦大学物理教学实验中心为培养学生创新能力开设的4门实验选修课的特点、要求以及在培养学生创新能力方面取得的成效。     

ZnSe及ZnSe/GaAs异质结构中压力导致的直接禁带向间接禁带的转变

用经验赝势方法计算了体ZnSe以及ZnSe/GaAs单异质结系统中ZnSe外延层г、X、L等特殊对称点导带底能量随压力的变化。结果表明，同Si、Ge、GaAs等半导体材料不同，ZnSe的X点导带底具有正的压力系数，但比г点的压力系数小，这是ZnSe材料以及ZnSe基异质结构材料发生直接禁带向间接禁带的转变时所需转变压力较大的根本原因。研究了ZnSe/GaAs异质结构中晶格失配造成的应变对外延层г、X、L对称点压力系数的影响，表明这种晶格失配造成的应变可以极大地减小ZnSe外延层材料由直接禁带向间接禁带的转变压力。     

同步辐射讲座第一讲 同步辐射XAFS实验站及其应用

介绍了北京和合肥同步辐射XAFS实验站的性能参数和结构, 及在物理，化学，材料和生命科学等研究领域的应用，便于国内广大用户更好地利用其开展高质量的研究工作。     

Trace analysis of polycyclic aromatic hydrocarbons using calixarene layered gold colloid film as substrates for surface‐enhanced Raman scattering

A surface‐enhanced Raman scattering (SERS) active substrate for the detection of polycyclic aromatic hydrocarbons (PAHs) was developed, which used 25, 27‐dimercaptoacetic acid‐26, 28‐dihydroxy‐4‐terbutyl calix[4]arene (DMCX) to functionalize a gold colloid film. This SERS‐active substrate prepared by self‐assembly method exhibits a high sensitivity, especially for the detection of PAHs. With the use of this SERS‐active substrate and with the application of the shifted excitation Raman difference spectroscopy (SERDS) technique, Raman signals of pyrene and anthracene in aqueous solutions at low concentration level (500 pM) can be obtained. Moreover, because PAHs are blocked from being directly adsorbed on gold colloid by DMCX and the photochemical reactions of adsorbates are avoided, the Raman bands of PAHs adsorbed on DMCX‐fuctionalized gold colloid film can be one‐to‐one correspondence with those of solid PAHs, and additionally, this SERS‐active substrate can be easily cleaned and reused. The obtained results demonstrate that the DMCX‐functionalized gold colloid films prepared by self‐assembly method have great potential to be developed to an in situ PAHs detection substrate. Copyright © 2012 John Wiley & Sons, Ltd.