Electronic absorption spectra of charge-transfer complexes and effects of substituents in radical cations

The effects of X substituents on the energies of charge-transfer bandshv _CT in electronic absorption spectra of charge-transfer complexes of π-, n-, or σ-donors (DX) with π- or σ-acceptors (A) as well as on the ionization potentialsI _D of individual DX molecules are described by the equationhv _CT(l _D)=a +bσ₁ +cσ _R ⁺ +dσ_α. When DX and A are fixed, the inductive (bσ₁), resonance (cσ _R ⁺ ), and polarization (dσ_α) contributions tohv _CT andI _D are virtually identical. The electronic structure of the D^.+X donor component of the compact [A^.−, D^.+X] radical-ionic pair in a solution is similar to that of the radical cation generated upon photoionization of the individual DX molecule in the gaseous phase. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1002–1006, June, 2000.     

N-(1-萘基)氨基乙酸的激发态分子内电荷转移和电子转移

氨基酸是蛋白质的基本结构单位 ,水溶液中基态氨基酸分子以内盐形式存在 [1] .由于质子化氨基的正诱导效应 ,羧基的离解常数显著提高 ,如氨基乙酸的羧基离解常数 ( 4.57× 1 0 -3mol/L,2 5℃ [1] )是乙酸 ( 1 .74× 1 0 -5 mol/L[2 ] )的 2 63倍 ;同时内盐结构亦使氨基酸和肽链具有分子内电偶极 ,后者已在肽链上电荷转移过程的调控中发挥重要作用 [3,4] .激发态氨基酸或肽的诱导效应和电偶极性质的研究尚未见报道 ,其主要原因可能是难有合适的激发方式和研究方法 .然而相关研究应予重视 ,因为研究结果将可能为生物酶活性的调节提供一种新的…     

基于脉冲电铸技术Ni-ZrO2纳米梯度功能材料的制备工艺

研究了在脉冲复合电铸过程中,当其它工艺参数一定时,镀液中纳米ZrO2颗粒含量、脉间、脉宽和阴极电流密度对复合电铸层中ZrO2复合量和沉积速率以及脉冲参数对复合电铸层表面形貌的影响,并对所制备复合电铸层的横截面进行了SEM观察和组成成分测定.结果表明,通过控制脉冲复合电铸过程中的工艺参数可以制备出由纳米颗粒复合量变化而导致其组织成分呈梯度分布的纳米功能梯度材料.     

Successive Deprotonation Steering the Structural Evolution of Supramolecular Assemblies on Ag(111)

In this study, we demonstrate the structural evolution of a two-dimensional (2D) supramolecular assembly system, which is steered by the thermally activated deprotonation of the primary organic building blocks on a Ag(111) surface. Scanning tunneling microscopy revealed that a variety of structures, featuring distinct structural, chiral, and intermolecular bonding characters, emerged with the gradual thermal treatments. According to our structural analysis, in combination with density function theory calculations, the structural evolution can be attributed to the successive deprotonation of the organic building blocks due to the inductive effect. Our finding offers a facile strategy towards controlling the supramolecular assembly pathways and provides a comprehensive understanding of the 2D crystal engineering on surfaces.     

新型电感储能脉冲功率驱动源

提出了将传统单个储能电感利用传输线分隔成两部分的新型电感储能脉冲功率驱动源技术方案。理论分析表明,利用传输线电容的耦合延时作用,可有效对调制器输出脉冲波形进行整形,并且可以进一步提高能量转换效率,从而克服传统电感储能脉冲功率源输出波形质量差(类三角波波形)的缺点。基于该思想开展了实验研究,获得了电压约300 kV,电流约20 kA的电子束,并成功驱动S波段磁绝缘线振荡器获得了百MW量级的微波输出。     

Inductive Limits of Area-Preserving Diffeomorphism Groups

A compact oriented surface with a given area form is considered. For each coordinate domain, we take the group of diffeomorphisms supported in this domain and preserving the area form. Finally, consider codimension 1 normal subgroups in these groups. For each pair of coordinate domains one of which contains the closure of the other, there is an obvious inclusion of the corresponding groups. We describe the inductive limits (amalgams) of these two families of groups.     

酰胺-尿素-NaBr熔体中电沉积Tb-Co合金的研究

在353K的乙酰胺 尿素 NaBr熔体中,Co(Ⅱ)一步不可逆还原为金属Co,测得α为0.23和D0为1.25×10-6cm2·s-1;Tb(Ⅲ)不能单独还原为Tb,但是可以被Co2+诱导而共沉积。由恒电位电解法得到非晶态的Tb Co合金;Tb的含量随阴极电位的负移、Tb3+ Co2+摩尔比增大及电解时间延长而增大,Tb的最大含量可达83.91wt%。Tb Co合金膜经高温晶化后用X射线衍射分析其组成为(TbCo3)12R。     

低温熔盐中电沉积Sm-Co合金膜及其磁性能

在353 K的尿素-乙酰胺-NaBr-KBr熔体中, 用恒电位电解法在Cu基片上制备了Sm-Co合金膜. 利用循环伏安法研究了熔体的电化学行为. 电化学实验结果表明, 在Pt电极上, Co(II)+2e→Co(0)是一步完全的不可逆反应; 测得CoCl2-尿素-乙酰胺-NaBr-KBr熔体中, Co(II)在Pt电极上的传递系数α=0.31, 扩散系数D0=4.78×10^-5 cm2·s-1; Sm(III)难以单独沉积, 但能被Co(II)诱导共沉积, 在不同阴极电位下制备出不同Sm含量的非晶合金膜. 用等离子发射光谱仪(ICP)检测薄膜成分, 用SEM观察了薄膜的表面形貌结构, 用XRD和振动样品磁强计(VSM)分析样品退火前后的晶相和磁性能变化特征. 结果表明, 在923 K进行退火30 s后Sm-Co薄膜由非晶转变为多晶结构, 并以hcp晶相结构为主; 退火和Sm含量对Sm-Co合金膜的磁性能有重要的影响.     

基于LabVIEW的旋转轮轴扭矩测试系统的设计

针对目前国内旋转动力机械动态扭矩测量中受环境因素影响大,精度低,稳定性差,操作使用不方便等问题,应用感应供电技术、无线通信技术、微功耗处理技术、虚拟仿真技术,设计了一种将WIFI无线传感器网络(WSNs)与虚拟仪器相结合的旋转轮轴扭矩测试系统,实现了动态扭矩参数的实时准确监测、在线校准、存储、分析、显示、预报预警及生成报表等功能,仿真和实测结果表明：该系统功耗低于0.05W,测量精度可达0.4%FS,动态响应好,操作简单,长时间运行稳定可靠。