电化学现场时间分辨电子自旋共振波谱

在电子自旋共振对电化学暂态过程的研究中，人们通常将磁场固定在对研究信号敏感的位置，记录ＥＳＲ强度随时间的变化。这种作法常导致大量的信息遗失，不但得不完整ＥＳＲ谱线的变化，也很难分析多种磁物种共存的情况。     

光透薄层光谱电化学法研究灿烂甲酚兰的电极过程

在铂网光透电极上,采用紫外-可见和电子顺磁共振(ESR)技术研究了灿烂甲酚兰(BCB)的电极过程。测定了BCB的标准式电极电位和电子转移数。结果表明,BCB在铂电极上进行可逆的单电子转移反应,并且氧化态和还原态均较强烈地吸附在铂电极上。ESR波谱的现场监测直接确证了单电子转移过程,并首次发现BCB的氧化态在正电位激发下呈三线态,还原态具有单电子自由基。另外对BCB的电极过程机理进行了初步探讨。     

表面等离子体共振光谱技术与电化学方法联用及其应用

表面等离子体共振（Surface Plasmon Resonance,SPR）技术是利用金属薄膜光学耦合产生的物理光学现象建立的一种非常灵敏的光学分析手段. 近年发展的电化学表面等离子体共振（Electrochemical Surface Plasmon Resonance,EC-SPR）是将时间分辨表面等离子体共振光谱技术与电化学方法联用的一种新技术. 本文介绍了SPR和EC-SPR的基本原理,并重点阐述了时间分辨SPR光谱技术与电化学方法联用及应用,该技术已广泛地应用于反应动态过程研究、生物化学传感器、电极/溶液界面的表征、动力学常数的测定以及生物分子相互作用等领域.     

水和非水体系现场电化学-电子自旋共振测量——电解池制作和初步结果

A simultaneous electrochemical-electron spin resonance(SEESR)cell has been designed. It is easily fabricated and operated and can be used for either aqueous or nonaqueous determation.Using this aparatus, the ESR signals were observed for nitrobenzcne anion radicals, produced by constant potential electrolysis of nitrobenzene in acetonitrile media with 0.1M TBAP as electrolyte and in 0.5M KCl aqueous solution respectively. The hyperfine coupling constants of the nitrobenzene anion radical have been estimated which are in accordance with the literature values.     

反射薄层光谱电化学方法的应用

用自行设计的反射光谱薄层电解池测定了二茂铁在NaClO_1/CH_3CN中的E~O′和n值、铁氰化钾在KCl底液中和亚甲蓝在KNO_3/DMSO中的扩散系数。对亚甲蓝在二甲亚砜介质中的还原过程进行了研究,证明有一电子还原产物存在。     

现场光谱电化学研究的新进展

电化学以两个凝聚相的荷电界面为其主要研究对象．它广泛地应用于能源、材料等重要科学领域，并对生命科学的发展发挥着重要作用［1，2］．为了从分子水平上深化对电化学界面的认识，自七十年代中至八十年代初采用了紫外可见反射、拉曼和红外光谱技术对电化学体系进行现场（in-situ，又称原位）研究，开创了光谱电化学新领域[3,4]．光谱电化学在／＼十年代发展迅速，推动电化学研究由宏观进入微观、由统计平均深入至分子水平【‘一刀．近年来，随着各种光谱仪器性能的提高以及非线性光谱等新技术的发展，现场光谱电化学研究不断拓宽新领域，…     

用于现场FTIR及UV/Vis光谱电化学的高质量简单结构的光透薄层电化学池

设计制作了一种应用于紫外可见、红外电谱电化学的新型光透薄层电化学池(OTTLE),并以铁氰化钾水溶液、二茂铁乙腈溶液体系进行了表征。池腔几何结构的合理设计使电位降和边缘效应降至最低。该池有良好的伏安响应特性并可用它得到高质量的UV/Vis和IR光谱。由于简单的结构及低廉的造价使适用于光谱电化学研究的电化学池变得更容易得到。     

2—氨基—9,10—蒽醌及其衍生物的光谱电化学研究

用循环伏安法研究了２－氨基－９，１０－蒽醌及其衍生物在ＤＭＦ－０．１ｍｏｌ／ＬＴＢＡＰ溶液中的电化学行为，结果表明它们在铂电极上均发生两步连续的单电子还原过程，取代基Ｒ及水和苯甲酸等质子性试剂的加对伏安曲线有很大的影响。     

固/液界面现场光谱电化学

固/液界面现场光谱电化学的方法包括各种电磁波透射和反射谱(紫外可见、拉曼、红外、X-光等)、磁共振谱(ESR、NMR)以及80年代发展起来的扫描显微谱(STM等)和非线性反射光谱(SHG)等等。固/液界面现场光谱电化学已渗透到固/液界面和电极表面结构,分子水平上的吸脱附和反应机理,电催化和反应动力学等许多研究领域。本文结合文献对上述几个方面以及固/液界面现场光谱电化学的发展方向进行综述。     

冰醋酸中肾上腺素的现场光谱电化学行为

采用以石墨为工作电极的长光程薄层光谱电化学池, 用循环伏安法、恒电位光谱法和单电位跃计时吸光度法,研究了肾上腺素(AD)在冰醋酸介质中的电子转移反应。结果表明:AD在冰醋酸介质中电氧化反应产物为肾上腺素醌,还原态和氧化态的扩散系数分别为 3. 98×10-6 cm2 /s和 3. 90×10-6 cm2 /s;电极反应的式量电极电位为 0. 632V(vs.SCE),式量异相电子转移速率常数为 7. 30×10-4cm/s;传递系数为 0. 15。     

Electron Spin Resonance Analysis of Carbon on Ruthenium Catalysts

Electron spin resonance (ESR) spectra of carbon radicals on Ru/Al₂O₈, catalysts have been studied. Carbon monoxide treatment resulted in three kinds of sorbed species: a weakly sorbed CO species associated with the anisotropic spectrum; a more tightly sorted carbon species, perhaps amorphous carbon; and another carbon species, which is essentially unreactive with oxygen and may be graphitic carbon.     

The Electron Spin as a Chiral Reagent

We show that enantioselective reactions can be induced by the electron spin itself and that it is possible to replace a conventional enantiopure chemical reagent by spin‐polarized electrons that provide the chiral bias for enantioselective reactions. Three examples of enantioselective chemistry resulting from electron‐spin polarization are presented. One demonstrates the enantioselective association of a chiral molecule with an achiral self‐assembled monolayer film that is spin‐polarized, while the other two show that the chiral bias provided by the electron helicity can drive both reduction and oxidation in enantiospecific electrochemical reactions. In each case, the enantioselectivity does not result from enantiospecific interactions of the molecule with the ferromagnetic electrode but from the polarized spin that crosses the interface between the substrate and the molecule. Furthermore, the direction of the electron‐spin polarization defines the handedness of the enantioselectivity. This work demonstrates a new mechanism for realizing enantioselective chemistry.     

A Generalized Unpaired Electron Spin Density Equation and Organic Hyperconjugation Mechanism

A large class of stereochemcial and related interactions in organic chemistry are repulsive and others are attractive, but the relative orientation of two methyl groups and the amount of energy required to twist one relative to the other (the hindered rotation energy barriers), or the alignment of such a group with respect to a conjugated ring to which it is attached (widely attributed to a mechanism called “hyperconjugation”) are estimated to be small in compared with the total energy of the molecule. We used theories of both isotropic and anisotropic proton hyperfine interactions in the π‐electron systems developed in the early sixties. They are approximated by the magnetic dipole nteractions between each proton and an electron spin magnetization that is distributed in 2s and 2p Slater atomic orbitals center on carbon atoms. We have extended these theories to the non‐planar olefinic cation radicals, which are very important in biochemistry as well as in petroleum catalysis. A three dimensional electron spin density equation has been developed in this paper to handle some Jahn‐Teller vibronic molecules. The new electron spin density equation related the observed proton hyperfine splittings to the non‐planar structures of the open‐chain alkene cation radicals generated by radiolysis and various chemical oxidation methods. The spin densities and the conformational calculations based on valence bond theory and symmetry principles are compared with some more elaborated molecular orbital calculations in the literature. The localized valence bond approaches are better in accord with our experimental results. The anomalous line‐width effect of the four methyl groups observed in the 2,3‐dimethyl‐2‐butene cation radicals also confirmed the positive sign of the electron‐proton hyperfine constant of hyper‐conjugation mechanism. A methyl substituent attached to a conjugated molecule often behaves as if it formed part of the region of conjugation; the charge appears to flow from the methyl group into the π electron system and it may also give rise to an appreciable dipole moment. Methylation also gives rise to an appreciable dipole moment, and the resultant red shift of electronic absorption bands is of some importance in the design of dye molecules.     

聚苯胺的电化学现场ESR-电导同步测量

本论文工作通过设计新型的电解池 ,首次实现了导电聚合物的电化学现场ESR_电导同步测量 .从获得的聚苯胺ESR信号及膜电阻随电极电势变化的精细图象看出 ,极化子晶格的形成与消亡决定了聚苯胺的导电行为 .从不同电势下聚苯胺的ESR饱和行为也得到Curie自旋与Pauli自旋相互转化的新证据 .     

Electron spin resonance of diluted solid solutions of Gd2O3 in CeO2

Electron spin resonance spectra of Gd³⁺ in diluted solid solutions of Gd₂O₃ in CeO₂ have been studied at room temperature for Gd concentrations between 0.01 and 1.00 mol%. While in the case of Mn²⁺:CeO₂ samples, both the linewidth and the line intensity go through a maximum between 0.2 and 0.4% Mn and then start to decrease, in the case of Gd³⁺:CeO₂ samples the linewidth and the line intensity increase monotonically with the dopant concentration. This as taken as evidence that in Gd₂O₃-CeO₂ diluted solid solutions there are no clustering effects similar to the ones observed in Mn:CeO₂ solid solutions. It is not clear why clustering effects are present in Mn:CeO₂ solid solutions and not in Gd:CeO₂ solid solutions; however, it seems reasonable to assume that this is due to the fact that the ionic radius of Mn²⁺ (81 pm) is about 25% smaller that that of Gd³⁺ (107.8 pm). In any case, the fact that Gd:CeO₂ solid solutions do not exhibit clustering effects means that ESR linewidth data can be used to estimate the concentration of Gd in CeO₂ samples, as it is possible to do in several solid solutions of paramagnetic ions in ceramic materials. The results also suggest that the range of the exchange interaction between Gd³⁺ ions in CeO₂ is about 0.89 nm.     

衬底对N@C60分子电子自旋共振谱的影响

N@C₆₀内嵌富勒烯是一种在量子科技领域有较高应用前景的分子。科学家们设计了一系列以内嵌富勒烯分子为基本量子单元的量子计算机模型,而构筑这样的模型具有极高的挑战。其中,由于内嵌富勒烯分子阵列的制备通常需要合适的衬底,而衬底与分子之间的相互作用会影响甚至破坏内嵌N原子的自旋信号。因此研究和理解衬底与内嵌富勒烯分子的相互作用具有重要的意义。本文制备了高质量的N@C₆₀分子,并采用扫描隧道显微镜对其在Au(111)表面的结构及电子态进行表征。通过对比N@C₆₀分子在Au(111)、Si(111)、SiO₂表面的电子自旋共振(ESR)信号随时间及其抽真空处理的变化,表明Au原子的核自旋与内嵌N原子的电子自旋的耦合作用是Au(111)表面N@C₆₀单分子层的ESR谱中内嵌N原子的信号衰减的主要原因。     

生物小分子的电化学分析研究 Ⅲ.维生素B_2电化学还原反应的表征

用电化学、光谱电化学和顺磁共振谱等方法对维生素B_2在粗热解石墨电极上的电化学还原机理进行了表征。结果表明维生素B_2在粗热解石墨电极上的还原为2e、2H~+过程,它先经1e、1H~+过程还原生成自由电子定域在N(5)上的自由基中间体,然后再经1e,1H~+过程还原为二氢核黄素。     

蒽醌/氢给体/氮氧自由基的瞬态电子自旋极化

用时间分辨电子自旋共振波谱仪研究了光解蒽醌/乙二醇、蒽醌/乙二醇/氮氧自由基体系的化学诱导动态电子自旋极化.实验结果指出，在蒽醌/乙二醇/氮氧自由基（AQ/EG/TEMPO）体系中，存在自由基三重态对（RTPM）和三重态（TM）极化的竞争，并由此讨论了三重态 自由基对的反应速率.     

Electron Spin Catalysis with Graphene Belts

Here, we report kinetic studies using electron spin resonance spectroscopy on spin catalysis reactions caused by using graphene belts which were synthesized by a radical coupling method. The results show that σ-type free radical species provide the dominant sites for catalytic activity through the spin-spin interaction, although there are some other influencing factors. The spin catalysis mechanism can be applied both in the oxygen reduction reaction (ORR) and in organic synthesis. The graphene belt spin catalyst shows excellent performance with a high ORR half-wave potential of 0.81 V and long-term stability with almost no loss of activity after 50 000 cycles in alkaline media. It also shows excellent performance in a benzylamine coupling with molecular oxygen to generate the corresponding imine at an average conversion of ≈97.7 % and an average yield of ≈97.9 %. This work opens up a new research direction for understanding aerobic processes in the field of spin catalysis.     

氧化锌纳米微晶的顺磁共振特性

半导体纳米微粒是制备新一代电子器件的理想材料［1，2］．电子自旋共振谱（ESR）是研究纳米微晶表面电子自旋构象和表面结构的一种有效方法．体相ZnO是一种抗磁性物质，通常观察不到顺磁共振信号（ESR）．有关ZnO纳米微晶电子顺磁共振特性研究还未见文献报导．本文ZnO纳米微晶是用微乳法制备的：这样就制成了纳米尺度的具有表面包覆的ZnO微粒有机溶胶．这里表面活性剂起着“空间位阻”作用，一方面防止成胶过程中粒子间的聚合，使胶粒均匀细小；另一方面，包覆能减少微粒表面缺陷，使粒子性质变得十分稳定．将上述制得的ZnO纳米微粒…