电化学原位紫外可见反射光谱法

电化学原位（ｉｎ－ｓｉｔｕ）紫外可见反射光谱法是七十年代发展起来的一种光谱电化学方法。它对在分水平上电极界面结构和表面氧化，钝化，吸附，化学修饰等电化学过程具有独特的优越性。本文对电化学原位紫外可见反射光谱技术及其在电化学中的应用和发展趋势作了简要的叙述。     

一种电化学调制光谱用电解池

电化学调制光谱,又称电反射谱,是近年来发展起来的现场光学测量新技术。其实验方法是:研究电极受到小幅度交流信号的激励,其反射率发生相应的交变响应,采用锁相技术,测     

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，…     

光电流谱、光致发光光谱和紫外可见吸收光谱在纳米半导体光电器件研究中的联用

在纳米半导体中由于纳米效应(如量子尺寸效应),其电子结构与块体半导体有所不同。进一步地,当纳米半导体与基底和其他组分结合制成器件后,其性质又受到基底或其他组分的影响,这两点导致了基于纳米半导体的光电器件的性能以及相应表征方法也大不相同。将光电流谱、光致发光光谱和紫外可见吸收光谱三种技术有机地结合起来,可以更好地表征纳米半导体的电子性质和光电性能。本文根据纳米半导体材料与电极的电子性质特点及其测量,结合本课题组前期工作,举例介绍三种谱学方法相结合应用于探究光伏电池和电致发光器件的纳米半导体材料的性能,以及纳米半导体材料表面态的表征。     

双波长薄层紫外可见光谱电化学测定多巴胺

多巴胺 (DA)和抗坏血酸 (AA)的吸收光谱在 2 0 0～ 30 0nm内重叠严重 ,但在电化学氧化状态下 ,DA的氧化产物在 2 10 ,30 0和 4 80nm有强吸收峰 ,AA的氧化产物在 2 0 0～ 4 0 0nm范围内吸收较弱且呈光滑平缓的斜坡。在此基础上 ,利用自行设计的长光程薄层光谱电化学池建立了一种双波长光谱电化学法测定DA。测定条件为 pH 6 .2的磷酸盐缓冲液 (PBS) ,0 .6V (vs.Ag/AgCl)电极电位 ,双波长 318/ 2 93nm ,线性范围为 4 .0× 10 - 6 ～ 2 .0× 10 - 4mol·L- 1,检出限为 2 .0×10 - 6 mol·L- 1。对 6 .2 0× 10 - 5mol·L- 1DA进行 11次平行测定 ,平均相对偏差为 2 .6 %。与文献报道的吸光光度法相比 ,该法具有较高的灵敏度和选择性 ,较为有效地消除了AA的干扰 ,回收率在 91.8%～ 10 0 .8%之间 ,结果满意     

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。     

现场压电红外反射光谱电化学研究邻联甲苯胺的电化学行为

利用现场压电红外发射光谱电化学技术研究邻联甲苯胺(OTD)在金电极上的电化学行为.压电电化学结果表明:电位范围对OTD氧化的影响很大.当电位扫至0.6 V时,氧化过程中中间体的生成和溶解的同时,部分未溶中间体在电极表面沉积.当电位大于0.65 V时,还有OTD的电化学氧化聚合.压电红外反射光谱电化学结果表明中间体是OTD第一氧化产物之间相互作用形成的.进一步考察了肝素大阴离子对OTD的氧化的影响.     

间苯二胺的电化学及紫外-可见薄层光谱电化学研究

研究了间苯二胺(MPD)在金电极和SnO₂;F膜电极上的循环伏安行为及在SnO₂;F膜电极上的紫外-可见薄层光谱电化学性质.获得了间苯二胺在SnO₂;F膜电极上电氧化的薄层恒电势电解-吸收光谱图,采用双对数法对紫外-可见薄层光谱电化学数据进行了处理.研究了间苯二胺的光谱及电化学性质,求得了间苯二胺的动力学修饰式量电位E⁰和αn等热力学参数.     

苯胺和邻氨基酚共聚的原位紫外-可见光谱电化学研究

采用原位紫外-可见吸收光谱法研究了苯胺(AN)和邻-氨基酚(OAP)在0.5 mol/L H2SO4溶液中的电化学共聚过程.结果表明,在AN和OAP的共聚过程中,OAP首先被氧化生成其阳离子自由基,对应于460 nm处的吸收峰,然后OAP阳离子自由基与继而生成的AN阳离子自由基和溶液中的AN和OAP单体发生交互反应,生成混合二聚物中间体,对应于490 nm处的吸收峰,此混合二聚物中间体再继续反应生成中性低聚物,对应于波长小于460 nm处的吸收峰.在研究不同浓度比的AN和OAP进行电化学共聚时发现,当溶液中OAP浓度增大时,对AN的聚合会产生抑制作用.     

In situ Electronic Spectroscopic Techniques far Interfacical Electrochemistry

The present paper cover a measurement system combining reflection spectroscopy photocurrent spectroscopy and photocapacitance spectroscopy, and a measurement system for time resloved reflection and transmission spectroscopy in the ultraviolet-visible spectral region built in suit to characterize electrochemistrical processes. A differential or subtractive spectral method with recpect to an electrode potential change has been adopted in both systems in order to obtain a high S/N ratio.     

The reaction mechanism of p-toluenediamine anodic oxidation: an in situ ESR-UV/Vis/NIR spectroelectrochemical study.

In situ ESR-UV/Vis spectroelectrochemistry is applied to obtain new insights into the intermediates and reaction products of the anodic oxidation of p-toluenediamine in aqueous solution at different pH values. A strong pH dependence of the stability of the cation radical is found. While the absence of a stable radical was proved by ESR spectroscopy at pH 2 and 10, this radical is detected at medium pH values and assigned to the semiquinonediimine structure. The UV/Vis absorption of the radical is observed at these pH values as well. The p-toluenediimine intermediate and the trimeric reaction product were followed during the electrode reaction by UV/Vis spectroscopy at all pH values.     

Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red–orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO₄/HNO₃ and H₂SO₄/HNO₃ mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs.     

In situ spectroelectrochemical studies on ladder-type oligomers in solution and the solid state

A series of thermally stable fluoranthenopyracylene oligomers with extended pi conjugation were studied by in situ ESR-UV/Vis/NIR spectroelectrochemistry with respect to their application in devices such as organic light-emitting diodes and field-effect transistors. The oligomers are both soluble in o-dichlorobenzene and form thin films by evaporation in the temperature range of 300-500 degrees C in vacuum. Their electrochemical behavior was studied in reduction (n doping) and oxidation (p doping) under standard voltammetric and thin-layer conditions. The HOMO and LUMO energies and the band gaps of all compounds under study were estimated from both electrochemical and UV/Vis/NIR spectroscopic data. The fluorene-type oligomers A(2)-A(6) and B(2) bearing flexible alkyl chains exhibit both reversible multistep reductions and oxidations. The spectroelectrochemistry indicates substantial differences in delocalization of the positive and negative charges in these ladder-type oligomers. The formation of doubly charged sigma dimers was observed for the first time for both the radical anion and radical cation of the same molecule (B(1)). The redox behavior of the oligomers was studied in the solid state and in solution.     

High-Resolution,Higher-Order UV/VIS Derivative Spectrophotometry

Derivative spectrophotometry has gained increasing importance in the past two years and is currently experiencing vigorous development. Following and introduction the present article provides a review of this extremely effective method. In particular, the advantages of higher-order derivative spectrophotometry (HODS method, n > 2) are discussed on the basis of practical examples from a wide range of analytical fields. The results are achieved with the aid of a newly developed analog computer unit, whereby for the first time readily reproducible, low-noise, on-line spectra can be obtained up to the 7th order and even, in favorable cases, up to the 9th order. In practice it has proved valuable to work with spectra of the 3rd to 5th order; but even higher derivations could be profitable for the separation of strongly superposed signals or for “fingerprinting”.