RCCo_3(CO)_9的电化学和RCCo_3(CO)_9~-的ESR谱研究

本文对三种RCCo_3(CO)_9及相应的自由基进行了电化学和ESR谱研究.电化学研究表明,RCCo_3(CO)_9被还原为自由基的难易与R的性质有关,RCCo_3(CO)_9在室温下可以稳定存在.在对分子轨道对称性分析的基础上对簇合物自由基的ESR谱进行了讨论.确定了超精细偶合常数的符号和未成对电子占据轨道的性质,计算了Co的3d轨道和4s轨道的自旋密度.     

Pt（IV）修饰的非晶态TiO2对2，4-二氯苯氧基乙酸的可见光降解

用溶胶-凝胶法制备了在可见光照射下具有光催化活性的掺杂P（t Ⅳ）离子的非晶态微孔TiO2，表面积为160～200 m2/g；含3.0%Pt（Ⅳ）的AMM-Ti具有最大的光催化活性. X射线精细结构分析（EXAFS）表明，单个的PtCl4分子均匀地分布在非晶态二氧化钛表面；用这种光催化剂降解2，4-二氯苯氧基乙酸时，2，4-二氯苯酚是主要的中间物，通过Langmuir-Hinshelwood 方程的线性形式估算了反应速率常数k 和吸附平衡常数K，研究了光催化起始反应速率和反应物起始浓度之间的关系，同时，提     

SiO_2上共溅射W-Si薄膜退火后的X射线衍射研究

用一个W-Si混合靶源, 以直流磁控溅射在SiO_2_ 上共溅射一层W-Si薄膜后, 进行500-1000℃ , 15s 的真空快速热退火, 发现薄层电阻随退火温度出现一反常的极大值. 用转靶X射线衍射研究分析了这一反常现象. 在直至1 1 0 0 ℃ 高温退火的样品中发现薄膜中存在W_5_Si_3_.它对薄层电阻有一定的贡献. 关键词：     

_Na_0.5_Bi_0.5_TiO_3结晶学表征及其固溶体的X射线研究

Na_0.5_Bi_0.5_TiO_3-BaTiO_3_ ,系统在一定组成范围内是性能优良而独特的超声换能器陶瓷新材料. 本文工作用X射线粉末衍射方法精确测定了单组分Na_0.5_Bi_0.5_TiO_3,的晶胞参数,提出与前所报道不同的新的晶胞类型; 在此基础上给出该系统不同组成点的晶格参数, 并对性能、晶格参数和组成之间关系和相关系作初步讨论. 关键词：     

Fabrication of high growth rate solar-cell-quality μc-Si:H thin films by VHF-PECVD

Several series of Si:H films were fabricated by the very high frequency plasma enhanced chemical vapour deposition (VHF-PECVD) at different substrate temperatures (T_s) and silane concentration (SC=[SiH_4]/[SiH_4+H_2]%). The results of Raman spectroscopy showed structural evolution of the Si:H films with the variation of T_s and SC. The results of x-ray diffraction (XRD) measurements indicated that T_s also influences the crystal orientation of the Si:H films. The modulation effect of T_s on crystalline volume fraction (X_c) is more evident for the high SC, which shows different trend compared to low SC. In addition, the growth rate of the films also showed a regular change with the variation of SC and T_s. Different samples in the series showed a similar increase in dark conductivity and a decrease in photosensitivity with increasing T_s and decreasing SC. Device-quality microcrystalline silicon materials were deposited at a high growth rate, characterized by relatively low dark conductivity and relatively high photosensitivity in a certain crystalline range. The microcrystalline silicon solar cell with a conversion efficiency of 4.55% has been prepared by VHF-PECVD.     

Finite-size effect and Kondo screening effect in an A-B ring with a quantum dot

The properties of the ground state of a closed dot－ring system with a magnetic flux in the Kondo regime are studied theoretically by means of a one-impurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. It is shown that at T=0, a suppressed Kondo effect exists in this system even when the mean level spacing of electrons in the ring is larger than the bulk Kondo temperature. The physical quantities depend sensitively on both the parity of the system and the size of the ring; the rich physical behaviour can be attributed to the coexistence of both the finite-size effect and the Kondo screening effect. It is also possible to detect the Kondo screening cloud by measuring the persistent current or the zero field impurity susceptibility χ_{imp} directly in future experiments.     

Interrogating fiber Bragg grating sensors by thermally scanning a demultiplexer based on arrayed waveguide gratings

We evaluate a wavelength interrogation technique based on an arrayed waveguide grating (AWG). Initial results show that the Bragg wavelength of fiber Bragg grating (FBG) sensors can be precisely interrogated by thermally scanning an AWG-based demultiplexer. The technique potentially offers a low-cost, compact, and high-performance solution for the interrogation of FBG distributed sensors and multisensor arrays.