氮氧自由基中的多光子化学反应(Ⅰ)(英文)

在不同光源照射下，作者利用乙基亚硝基有机化合物在乙醇溶剂下，产生双光子的化学反应，用电子自旋共振吸收谐振腔为反应器．在不同的流速下，生成3种同分异构自由基．其结构由电子自旋共振光谱确定、微观的氢键跳动频率由不同波形的氮核超精细偶合常数的变化而确定、利用Charm软件计算，确定β-氢超精细偶合常数的意义及其几何形状．     

氮氧自由基中的多光子化学反应(Ⅰ)

在不同光源照射下,作者利用乙基亚硝基有机化合物在乙醇溶剂下,产生双光子的化学反应,用电子自旋共振吸收谐振腔为反应器.在不同的流速下,生成3种同分异构自由基.其结构由电子自旋共振光谱确定、微观的氢键跳动频率由不同波形的氮核超精细偶合常数的变化而确定、利用Charm软件计算,确定β-氢超精细偶合常数的意义及其几何形状.     

外来杂质Fe^3＋与照相明胶相互作用的研究

采用Ｘ射线光子能谱和电子自旋共振技术研究了外来杂质Ｆｅ＾３＋与照相明胶的相互 。结果表明,明胶对外来的３价铁有很强的还原能力。不同的明胶对外来铁的还原容量不同,相对于惰胶中所允许的含铁量,这个还原容量是相当高的,超过这个容量后,外来的３价铁离子将部分保持原有价态而不被还原。在这个容量以内,外来的３价铁将全部被还原,还原后的铁以络合形态存在于明胶中,其微观配位化学环境与明胶中本身存在的铁的配位环境有     

微波顺磁共振信号的讨论

本文根据反射式速调管的输出功率与频率特性，对微波电子自旋共振实验中共振吸收信号进行了详细讨论，并提出了不同的观察与分析的方法。     

基于开路谐振环的电子自旋共振系统设计与表征

本文采用有限元电磁仿真设计了基于开路谐振环的微带线谐振器,并利用该谐振器搭建了电子自旋共振测试系统．该谐振器的3 dB带宽为58.7 MHz,且具有开放式的平面结构．对不同质量的二苯基三硝基苯肼（DPPH）样品测试结果显示本系统的室温自旋探测灵敏度可以达到9.66×10¹² spins/Gs Hz^1/2;对以微晶玻璃和硅片为基底的DPPH样品测试结果表明本系统能实现对大尺寸、高损耗样品的电子自旋共振信号的非破坏性测量．本系统为薄膜材料的缺陷研究以及相关的微波性能表征提供了便捷的手段．     

InAs单层和亚单层结构中的自旋动力学研究

利用偏振时间分辨光谱和时间分辨Kerr旋转谱，研究了GaAs中的InAs单层和亚单层的电子自旋动力学.实验发现，在非共振激发条件下，厚度为1/3单层的InAs亚单层中电子自旋弛豫寿命长达3.4ns，而1个单层厚的InAs层的电子自旋寿命只有0.48ns；而在共振激发条件下，亚单层结构中的电子自旋寿命大大减少，只有70ps，单层InAs中电子自旋寿命没有显著变化.分析表明，低温下InAs单层和亚单层结构中，Bir-Aronov-Pikus(BAP)自旋弛豫机理占主导地位.通过改变材料结构特性和激发条件来改变电子空穴的空间相关性，从而达到控制自旋弛豫的目的. 关键词： InAs亚单层 自旋弛豫 BAP机理     

吩噻嗪-对苯醌体系光化学过程的时间分辨ESR研究

报道了用时间分辨电子自旋共振波谱仪对吩噻嗪与对苯醌的乙二醇溶液体系的紫外光照过程进行实时检测,从测得的电子自旋共振极化港可知,电子转移和质子转移在光照过程中同时存在并且相互竞争.     

利用电子自旋共振测量自由基未成对电子的朗德g因子和超精细结构

应用了电子自旋共振技术来研究有机半导体1,1-二苯基-2-三硝基苯肼(DPPH)中自由基未成对电子的超精细结构和塞曼劈裂.通过测量共振磁场大小和微波频率,我们得到了自由基未成对电子的朗德g因子.在实验中,一种混合接头(magic-T)波导管被用来提高信噪比.朗德g因子的测量结果为2.033±0.0003,与其他实验中测得的期望值2.0036相吻合.这个方法可以用以研究各种材料、生物系统中自由基未成对电子,并可进一步应用于研究电子芯片微电感上的自由基.     

S为1/2体系粉末或冷冻玻璃态电子自旋共振谱的模拟

本文较详细地介绍了模拟s为1/2体系粉末或冷冻玻璃态电子自旋共振谱的理论基础。给出了具体计算公式,利用这些公式完全可以在微机上进行计算机模拟电子自旋共振谱。     

基于微波段电子自旋共振测量电磁波的传播速度

当电子自旋共振发生在微波段时,根据微波段电子自旋共振条件,并使用电子顺磁共振谱仪和微波元件(波导管、谐振腔、短路活塞、环行器)等实验仪器测量出微波的波导波长,可以计算出真空中微波的波长.利用特斯拉计测量出共振时的磁感应强度,从而计算出了电磁波的传播速度.     

6－硝基喹啉的电化学还原及现场ESR研究

用循环伏安法与现场ＥＳＲ方法结合，研究了６－硝基喹啉在ＤＭＳＯ介质中，Ｐｔ电极上的电化学行为，检测到了电化学还原的中间产物阴离子自由基，估算了阴离子自由基衰变的速度常数，提出了６－硝基喹啉电化学还原的机理。     

溶液自由基ESR谱的计算机模拟

根据溶液自由基电子自旋共振(ESR)原理,用高级BASIC语言编写了溶液自由基谱的模拟程序。自由基的ESR能级用一级近似求解,谱线的线型采用洛仑兹和高斯型的混合线型函数,程序规定体系中核自旋量子数可从1/2到7/2,不等性核的数目最多可达10组,每组中等性核的数目原则上不受限制。通过二萘嵌苯阳离子自由基和硝基苯负离子自由基谱模拟二个例子加以说明,模拟结果是满意的。     

TX-100胶束中光解蒽醌的TR-ESR研究

用时间分辨电子自旋共振(TRESR)波谱仪研究了光解蒽醌自由基的化学诱导动态电子极化(CIDEP).实验测量表明,在蒽醌/乙二醇/TX-100体系中,蒽半醌自由基AQH·有很强极化ESR信号,在激光激发后~0.8μs,检测到蒽醌负离子基AQ·^-的信号,表明AQH·自由基部分地离解为负离子基AQ·^-.     

Electron spin resonance investigation of carbon-13 hyperfine interactions in nitrobenzene anion radical

Synthesis of carbon-13 enriched nitrobenzene which contains 22·5 mole per cent of nitrobenzene-1-¹³C and an equal amount of nitrobenzene-4-¹³C has been accomplished. We report the carbon-13 hyperfine interactions in the corresponding anion radicals in a variety of solvent media. In hexamethylphosphoramide a _C1 = -7·05 gauss and a _C4 = 6·14 gauss. These couplings change to -9·03 gauss and 5·31 gauss, respectively, when the solvent medium is dimethylformamide containing 0·598 mole fraction of water. The solvent dependence of a _C1 is consistent with the radical remaining planar as opposed to adopting a pyramidal conformation at the nitrogen when hydrogen bonds form between the radical anion and protic solvents. Data reported here provide an experimental means to estimate the spin density distribution in nitrobenzene anion.     

Ultrasonic effects on electroorganic processes. Part 14. Indirect electroreduction of benzyl chlorides with anthracene redox-mediatory system

Ultrasonic effects were observed in the indirect electroreduction of benzyl chlorides with a radical anion mediator electrogenerated from anthracene. Both the current efficiency for the toluenes formed and the current density (reaction rate) at a working electrode were significantly increased in potential-controlled electrolysis under ultrasonic irradiation (20 kHz). These effects are important from a practical aspect and are rationalized as being due to mass transport promotion caused by ultrasonic cavitation. Although the efficiency could be also increased in the direct electroreduction in the absence of the mediator under irradiation, the current density was only slightly increased.     

Binary composite ionic liquids [bmim][BF4] and [bmim][Ac] for electrochemical reduction of nitrobenzene

The binary composite ionic liquid mixtures composed of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) and 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) were studied and used in electroreduction of nitrobenzene for the first time. ¹H NMR and Fourier transform infrared (FTIR) spectroscopy were carried out to acquire a deep understanding of the interaction of binary ionic liquids, and UV/Vis spectroscopy was used to study the interaction between the mixture of ionic liquids and nitrobenzene. It was found that chemical shifts of all protons were changed and significant changes in the anion IR bands were induced, and the UV maximum absorption wavelength and absorbance of nitrobenzene in binary ionic liquids were different from those in the neat ionic liquid. The electrochemical reduction behavior of nitrobenzene in binary composite ionic liquids on platinum electrode was studied by cyclic voltammetry, in situ Fourier transform infrared spectroscopy, and constant potential electrolysis. Results indicated that the reduction of nitrobenzene in binary composite ionic liquids demonstrated higher current densities with a more positive potential, and the product (azobenzene) showed higher yield and selectivity in the composite ionic liquids than in the neat ionic liquids; the concentrations of water in the binary mixtures of ionic liquids had great effect on the electrochemical behavior of nitrobenzene. In the end, the mechanism of reduction of nitrobenzene in binary mixtures of ionic liquids was discussed.     

二苯乙烯在CdS胶体界面和醇溶液中光氧化反应的ESR研究

采用ＥＳＲ方法研究了二苯乙烯在硫化镉超微纳米粒子界面光氧化过程产生的中间体及转化机理，并与均相直接光氧化和在甲基紫精存在下的光氧化进行了比较。结果表明，二苯乙烯的界面光氧化经历了超氧阴离子基和二苯乙烯正离子基的生成过程而且在ＣＤＳ胶粒表面有Ｈ原子的生成；羟基在Ｈ原子产生过程中起着重要的作用。     

Radical anions containing the dioxidated 1,2,5‐thiadiazole heterocycle

Radical anions of 3,4‐aryl disubstituted 1,2,5‐thiadiazole 1,1‐dioxide were obtained by chemical and electrochemical reduction of their substrates, and characterized by ESR spectroscopy and cyclic voltammetry. The radical anion of the phenanthro[9,10‐c]‐1,2,5‐thiadiazole 1,1‐dioxide was found to be very stable in an aprotic solvent solution and did not react readily when water was added to the aprotic solvent, or the solution was saturated with oxygen gas. The radical formation chemical reaction competed with nucleophilic addition to the C?N bond of the thiadiazoles. A possible reaction mechanism, and a common reaction intermediate, supported by density functional theory calculations, is presented for the most stable radical. Copyright © 2009 John Wiley & Sons, Ltd.     

菁染料光敏化超氧自由基的产生

本文用自旋捕捉技术研究了青染料在含氧的二甲基亚用溶液中将氧光还原成超氧自由基的反应,在水溶液中光照时产生的羟基自由基来源于是初形成的O₂^·。超氧负离子的形成是由于电子从激发态染料转移至溶解的氧,各种染料的光致ESR信号强度与染料的氧化还原电位有关。     

消自旋ESR法测量铝酞菁光敏反应中阴离子自由基的生成

用氮氧自由基消自旋ESR法探测铝酞菁原初反应过程中的阴离子自由基.结果显示在无氧条件下,当体系中存在连苯三酚或半胱胺酸这些电子施主时,可有铝酞菁阴离子自由基生成,这可能是除了单线态氧外的另一种光敏作用机制.