Spectroelectrochemistry study

This report was complemented by a mediated electrochemistry study using horse cytochrome c as the electron acceptor. This was followed up by an unmediated thin layer optical spectroelectrochemistry study of chicken liver SO using a Au electrode modified by 4-pyridinethiol (Aldrithiol). Reversible changes in the heme absorption spectrum were seen and the caleulated heme redox potential (-115 mV vs. Ag/AgCl) was consistent with previous studies using optical potentiometry and cyclic voltammetry. ... 

The above theoretical treatments have involved the assumption of potential control after all, this is the most useful and common approach in spectroelectrochemistry studies because the electrodes are very resistive and are not equipotential under galvanostatic conditions. Galvanostatic... 

S Spectroelectrochemistry studies in niobium-containing chloride melts... 

Liu Y, Lin XQ (1999) Electrochemistry and spectroelectrochemistry study of manganese phthalocyanine in nonaqueous media. Chin J Anal Chem 27(9) 1026-1028... 

Semiconductors. In Sections 2.4.1, 4.5 and 5.10.4 basic physical and electrochemical properties of semiconductors are discussed so that the present paragraph only deals with practically important electrode materials. The most common semiconductors are Si, Ge, CdS, and GaAs. They can be doped to p- or n-state, and used as electrodes for various electrochemical and photoelectrochemical studies. Germanium has also found application as an infrared transparent electrode for the in situ infrared spectroelectrochemistry, where it is used either pure or coated with thin transparent films of Au or C (Section 5.5.6). The common disadvantage of Ge and other semiconductors mentioned is their relatively high chemical reactivity, which causes the practical electrodes to be almost always covered with an oxide (hydrated oxide) film. 

Having defined in situ and ex situ methodology, we have seen that in situ spectroelectrochemistry (simultaneous electrochemistry and spectroscopy) is a powerful technique for studying electrode processes. 

Optical Spectroscopy General principles and overview, 246, 13 absorption and circular dichroism spectroscopy of nucleic acid duplexes and triplexes, 246, 19 circular dichroism, 246, 34 bioinorganic spectroscopy, 246, 71 magnetic circular dichroism, 246, 110 low-temperature spectroscopy, 246, 131 rapid-scanning ultraviolet/visible spectroscopy applied in stopped-flow studies, 246, 168 transient absorption spectroscopy in the study of processes and dynamics in biology, 246, 201 hole burning spectroscopy and physics of proteins, 246, 226 ultraviolet/visible spectroelectrochemistry of redox proteins, 246, 701 diode array detection in liquid chromatography, 246, 749. 

Thus, in this example, combination of pH effects and spectroelectrochemistry proves very beneficial in the detailed study of merging of POM waves. 

Electropolymerized thin films of Zn(II)-4,9,16,23-tetraaminophthalocyanine immersed in a solution of relatively high pH have been studied using electrochemistry and spectroelectrochemistry [483]. 

Spectroelectrochemistry [3] is the field in which electrochemistry is combined with spectroscopy. Spectroelectrochemical techniques are useful in studying the electrochemical phenomena that occur both in solutions and at electrode surfaces. Here, only the phenomena in solutions are considered. 

Cyclic voltammetry has gained widespread usage as a probe of molecular redox properties. I have indicated how this technique is typically employed to study the mechanisms and rates of some electrode processes. It must be emphasized that adherence of the CV responses to the criteria diagnostic of a certain mechanism demonstrates consistency between theory and experiment, rather than proof of the mechanism, since the fit to one mechanism may not be unique. It is incumbent upon the experimenter to bring other possible experimental probes to bear on the question. These will often include coulometry, product identification, and spectroelectrochemistry. 

When Desilvestro and Pons used in situ IR reflection spectroelectrochemistry to observe the reduction of C02 to oxalate at Pt electrodes in acetonitrile [83], two different forms of oxalate were observed. Similarly, Aylmer-Kelly et al. studied C02 reduction in acetonitrile and propylene carbonate at Pb electrodes [84], by using modulated specular electroreflectance spectroscopy. Subsequently, two radical intermediates were observed which they determined to be the C02 radical anion, C02, and the product of the radical anion and C02, the (C02)2 adduct (see Equations 11.9 and 11.10). Vassiliev et al. also studied the reduction of C02 in... 

To a large extent, the discovery and application of adsorption phenomena for the modification of electrode surfaces has been an empirical process with few highly systematic or fundamental studies being employed until recent years. For example, successful efforts to quantitate the adsorption phenomena at electrodes have recently been published [1-3]. These efforts utilized both double potential step chronocoulometry and thin-layer spectroelectrochemistry to characterize the deposition of the product of an electrochemical reaction. For redox systems in which there is product deposition, the mathematical treatment described permits the calculation of various thermodynamic and transport properties. Of more recent origin is the approach whereby modifiers are selected on the basis of known and desired properties and deliberately immobilized on an electrode surface to convert the properties of the surface from those of the electrode material to those of the immobilized substance. 

There are several major areas of interfacial phenomena to which infrared spectroscopy has been applied that are not treated extensively in this volume. Most of these areas have established bodies of literature of their own. In many of these areas, the replacement of dispersive spectrometers by FT instruments has resulted in continued improvement in sensitivity, and in the interpretation of phenomena at the molecular level. Among these areas are the characterization of polymer surfaces with ATR (127-129) and diffuse reflectance (130) sampling techniques transmission IR studies of the surfaces of powdered samples with adsorbed gases (131-136) alumina(137.138). silica (139). and catalyst (140) surfaces diffuse reflectance studies of organo- modified mineral and glass fiber surfaces (141-143) metal overlayer enhanced ATR (144) and spectroelectrochemistry (145-149). 

Cells for Spectroelectrochemistry. Spectroscopic techniques have been used in conjunction with electrochemistry in a variety of ways, which can be grouped into three areas the direct optical study of the electrode interface, the... 

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