Electrochemical and spectroscopic methods

Bullock, K. R., Electrochemical and Spectroscopic Method of Characterising Lead Corrosion Films , J. Electroanal. Chem., 222, 347-366 (1987)... 

Effects of spacer groups on the formation and properties of the mixed-valence states of conjugated ferrocene dimers have been extensively studied by both electrochemical and spectroscopic methods. It should be noted that a characteristic feature in the electronic spectra of ferrocene dimers with conjugated spacer groups is the appearance of metal-to-ligand charge transfer (MLCT) bands in the neutral form as well as IT bands in the mixed-valence state. The dimer Fc — CH=CH — Fc... 

In Chapter 2, the electrochemical oxidation of carbon monoxide, which is considered as the key intermediate for methanol oxidation, is investigated using electrochemical and spectroscopic methods for polycrystalline and single crystal platiniim electrodes. In Chapter 3, the electrochemical oxidation of methanol on the same electrodes was treated. In Chapter 4, electrocatalytic activities of platinum modified by adding secondary elements will be disciissed. 

Although the instrumental techniques described here give detailed mechanistic information, they do not provide an insight into the structure of intermediates. If we, however, combine electrochemical and spectroscopic methods, this is advantageously accomplished (spectroelectrochemistry) [73]. Various spectroscopies have been coupled with electrochemical experiments, among them ESR [74], optical [75], and NMR spectroscopy [76, 77], as well as mass spectrometry [78, 79]. 

An intermediate in an electrode process often can be studied directly by electrochemical and spectroscopic methods, or its existence can be inferred from product and kinetic analyses. In the present example, the intermediacy of the p-cyanophenyl radical can be demonstrated by a trapping experiment (refer to Fig. 21.3). 

Experimental evidence of the presence of specific adsorption can be found from thermodynamic measures both from the values of relative excesses or from the shift of the PZC with the electrolyte concentrations [19]. Currently, this presence can be determined from the combination of electrochemical and spectroscopic methods [4]. 

In the last chapter, Strehblow provides a review of experimental methodology and theoretical concepts of passivation and passivity of metals. The topics of emphasis include growth and composition of passive layers, their structure and electronic properties, and their breakdown. Current accomplishments are discussed in detail for a selected number of key metal and alloy systems. Summarized in some detail are the most important analytical methods for elucidation of chemical composition, electronic properties and structure of passive layers. It is shown for many systems that the application of multiple combinations of electrochemical and spectroscopic methods provide many insights and confidence in the interpretation of the passive behavior of metals. 

Electrochemical and Spectroscopic Methods. Cyclic voltammetry (CV) was done using a conventional three-compartment cell with the anode and cathode compartments separated by a fine porosity fritted glass disk. All experiments were done under a nitrogen blanket at... 

In the detection modes applied to ion chromatography one distinguishes between electrochemical and spectroscopic methods. Conductometric and amperometric detection are electrochemical methods, while the spectroscopic methods embrace UV/Vis, fluorescence, and refractive index detection. Added to this are the various applications of these detection methods, described in detail below. 

Of the many forms of detection used in IC, conductometric detection is still the most popular. However, all other methods such as electrochemical and spectroscopic methods are more often applied especially for the analysis of trace ions in samples with complex matrices. 

The electrochemical behavior of Nb(V) in oxide free basic aluminum chloride -methyl-3-ethylimidazolium chloride - is reported to involve four reduction steps, but reduction to the free metal could not be achieved [1, 2]. Niobium and tantalum chloride cluster cores of the type [M6C1i2] (M=Nb or Ta) in this same ionic liquid have been studied in detail by electrochemical and spectroscopic methods and their behavior compared with the behavior of these systems in an MeCN electrolyte. Four reversible redox states are observed in the span z = 2-5 [3, 4]. 

Electrochemical and spectroscopic methods have been used to investigate irreversible-loss mechanisms of lithium intercalation in disordered polymethacrylo-nitrile carbons. Voltammetric measurements show that the solvent readily decomposes at potentials 1.2 V positive of the reversible lithium potential. Evidence for hydrocarbon, carbonate and alkylcarbonate formation in the surface film is found with the help of combined XPS and SIMS analysis. 

Sorunmu, Y. E. Nguyen, M. Sapp, J. B. Gorski, W. Phan, T. D. Wei, X. Study of factors affecting molecular behaviors in phenothiazine-mediated biosensing by electrochemical and spectroscopic methods. Electroanalysis 2006, 18, 2375-2380. 

The study described above provides fundamental accounts of enzyme behavior, albeit following chemical treatment, and at 77 K. Thus, although the findings are significant, it is unclear if the mechanism can be extrapolated to room temperature and physiologically relevant electrochemical conditions, such as those in a BFC. Thus, the primary benefit of the XAS studies described herein is the ability to investigate laccase in situ, under realistic electrochemical and BFC conditions, and correlated to various electrochemical and spectroscopic methods. 

Values of Kd obtained by electrochemical and spectroscopic methods are summarized in Table 4. For comparison, data found by proton NMR are... 

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