用侧向外延生长法降低立方相GaN中的层错密度

尝试用侧向外延（ELOG）方法来降低立方相GaN中的层错密度。侧向外延是在SiO_2/GaN/GaAs图像形底上进行的，对生长所得的立方相GaN外延层用扫描电子显微镜（SEM）和透射电子显微镜（TEM）进行了观察和分析，TEM的平面像表明经过ELOG方法生长后，立方相GaN外延层中的层错密度由侧向外延生长前的5 * 10~9cm~(-2)降低至生长后的6 * 10~8cm~(-2)。双晶X射线衍射（DCXRD）测量给出侧向外延前后外延层ω扫描（002）衍射摇摆曲线的半高宽（FWHM）分别为33’和17.8’，表明晶体质量有了较大改善。对立方相GaN侧向外延过程中层错减少的机制进行了讨论。

分子束外延生长高应变单量子阱激光器（英文）

采用分子束外延方法研究了高应变InGaAs/GaAs量子阱的生长技术。将InGaAs/GaAs量子阱的室温光致发光波长拓展至1160nm，其光致发光峰半峰宽只有22meV。研制出1120nm室温连续工作的InGaAs/GaAs单量子阱激光器。对于100μm条宽和800μm腔长的激光器，最大线性输出功率达到200mW，斜率效率达到0.84mW/mA，最低阈值电流密度为450A/cm~2，特征温度达到90K。

HIRFL单丝束流剖面监测器的运动控制系统

在HIRFL的束流诊断中,研制了单丝束流剖面监测器。文章介绍了单丝束流剖面监测器运动控制部分基于PLC和步进电机驱动器的实现,对运动控制系统的硬件和软件的设计做了详细的介绍。整个系统已经通过调试,能够满足在HIRFL束流诊断中对运动控制的要求。

离子辐照对聚苯乙烯低温导电特性的影响

室温下用 3MeV的硅离子对聚苯乙烯 (PS)进行辐照 ,对辐照后的样品在室温至液氮温度范围的导电特性进行了测量 .结果表明 ,当辐照剂量在 1× 10 1 2 cm- 2 附近 ,PS的室温电阻发生突变 .随着温度的降低 ,PS电阻增大 ,在低辐照剂量下 ,电阻在 15 5K附近急剧增加 .对于高辐射剂量样品 ,在较高的温度下呈现热激活导电 ,在低温下电子通过隧穿传导 .分析认为 ,PS电阻随温度的变化是由于不同剂量辐照离子在聚合物中形成的对电子传导有贡献的导电中心密度不同 .通过拟合样品的渗流临界特性 ,分析了样品电阻随辐照剂量的变化

Rotamers of m-aminophenol cation studied by mass analyzed threshold ionization spectroscopy and theoretical calculations

The vibrationally resolved spectra of selected rotamers of m-aminophenol have been recorded by mass analyzed threshold ionization spectroscopy in connection with two-color resonant two-photon excitation scheme. The adiabatic ionization energies of the cis and trans rotamers are 61460 +/- 5 and 61734 +/- 5 cm(-1), respectively. The frequencies of modes 1 (breathing) and 18a (in-plane CH bending) are measured to be 744 and 1097 cm(-1) for the cis, and 736 and 1104 cm(-1) for the trans rotamer, respectively. This indicates that different orientation of the OH with respect to the NH2 substituent only slightly influences these two modes. (C) 2004 Elsevier B.V. All rights reserved.

不同时间尺度径流对植被变化的响应

植被覆盖对陆地生态系统的水分循环起着重要作用。径流对植被变化在不同时间尺度的响应研究,对区域生态环境建设及水资源管理具有重要的参考价值。该文介绍基于对比流域法,在多年平均、年际、季节等不同时间尺度径流对植被变化响应的研究结果。多年平均尺度上,由植被类型更替引起的径流绝对变化量,湿润区较干旱区大,其相对变化量在干旱区严重;年际尺度上,因植被变化,径流从一种平衡状态到另一种平衡状态的响应时间因抚育措施和地区不同而不同,造林情况下,湿润地区一般需要15~20 a,干旱地区约需25 a甚至更长,森林自然恢复情况下则需要上百年;季节尺度上,径流对植被变化的响应在季风影响区较四季湿润地区强烈。流量历时曲线研究表明,干旱地区造林,其基流无论在量或发生概率的变化上均较湿润区强烈。

A novel alcohol dehydrogenase biosensor based on solid-state electrogenerated chemiluminescence by assembling dehydrogenase to Ru(bpy)(3)(2+)-Au nanoparticles aggregates

Based on electrogenerated chemiluminescence (ECL), a novel method for fabrication of alcohol dehydrogenase (ADH) biosensor by self-assembling ADH to Ru(bpy)(3)(2+) -AuNPs aggregates (Ru-AuNPs) on indium tin oxide (ITO) electrode surface has been developed. Positively charged Ru(bpy)(3)(2+) could be immobilized stably on the electrode surface with negatively charged AuNPs in the form of aggregate via electrostatic interaction. On the other hand, AuNPs are favourable candidates for the immobilization of enzymes because amine groups and cysteine residues in the enzymes are known to bind strongly with AuNPs. Moreover, AuNPs can act as tiny conduction centers to facilitate the transfer of electrons. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate, and it displayed wide linear range, high sensitivity and good stability.

稀土铽离子对辣根过氧化物酶活力指数的影响

The effect of Tb3+ ion on the Activity Index (RZ=A403/A275) of HRP was investigated by a combination of ultraviolet-visible, FT-infrared and X-ray photoelectron spectroscopic techniques. It was found that Tb3+ ion could bond to the O and/or N group of the amides in the polypeptide chains of HRP, leading to a decrease in the enzymatic activity index of HRP.

Organic white-light-emitting devices based on a multimode resonant microcavity

Organic white-light-emitting devices ( OLEDs) based on a multimode resonant microcavity defined by a pair of dielectric mirrors and metal mirrors were presented. By selective effects of the quarter-wave dielectric stack mirror on mode, white light emission containing three individual narrow peaks of red, green and blue was achieved, and showed weak dependence on the viewing angle. The Commission Internationale De L'Eclairage ( CIE) chromaticity coordinates changed from ( 0.29, 0.37) at 0 degrees to ( 0.31, 0.33) at 40 degrees. Furthermore, the brightness and electroluminescence efficiency of the microcavity OLEDs were enhanced compared with noncavity OLEDs. The maximum brightness reached 1940 cd m(-2) at a current density of 200 mA cm(-2), and the maximum current efficiency and power efficiency are 1.6 cd A(-1) at a current density of 12 mA cm(-2) and 0.41 1m W-1 at a current density of 1.6 mA cm(-2), which are over 1.6 times higher than that of a noncavity OLED.

Electrocatalytic oxidation of ascorbic acid by ferrocene in lipid film cast on a glassy carbon electrode

A ferrocene-dimyristoyl phosphatidylcholine (DMPC) film electrode was prepared by casting the solution of ferrocene and DMPC in chloroform onto a glassy carbon electrode surface. Ferrocene retained in the biological membrane gave a couple of irreversible peaks of cyclic voltammogram. The electrode exhibited good electrocatalytic activity for the oxidation of ascorbic acid (H(2)A) in phosphate buffer (pH 6.64) with an anodic peak potential of +340 mV (vs. Ag/AgCl). The anodic current was directly proportional to the square root of the scan rate below 150 mV s(-1). The influence of the pH value was investigated and it was observed that pH 6.64 was the suitable value to the anodic peak potential and current. The thickness of the film and the interference of uric acid were also studied. The electrode can be used to determine H(2)A in the presence of equimolar uric acid. The catalytic peak current increased linearly with the concentration of H(2)A in the range of 1 X 10(-4)-5 X 10(-3) mol L-1.

探测束偏转光谱电化学

评述了探测束偏转光谱与电化学手段相结合作为一种现场的光谱电化学技术在研究电极／电解质界面上的应用。分别从实验装置、偏转原理、影响因素及其应用等方面加以论述。

醋酸纤维素为母体的稀土离子选择性电极的研制

醋酸纤维素为母体的稀土离子选择电极,制备容易,使用方便,可以测定混合稀土,电极的线性范围为1.2×10~(-1)～1×10~(-5)mol/L,适宜的pH范围较宽,测定结果令人满意。