Electrochemical and Raman spectroscopic investigations of in situ and emersed silver-alcohol electrochemical interfaces.
AuthorSobocinski, Raymond Louis.
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PublisherThe University of Arizona.
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AbstractThe overall goal of this research is to characterize the potential-dependent structure and composition of the alcohol-Ag electrochemical interface. The approach involves the use of a variety of electrochemical and spectroscopic tools to arrive at a consistent model for a series of straight-chain alcohols (methanol, ethanol, 1-propanol, and 1-pentanol) at Ag electrodes. There are essentially four areas of investigation presented in this dissertation. The first portion of this work has been directed at the development of charge coupled device detection in Raman spectroscopy so that many of the interface investigations could be performed. The advantages and limitations of these detectors in Raman spectroscopy are addressed. The second area involves the characterization of in-situ alcohol-Ag electrochemical interfaces using Raman spectroscopy and associated surface selection rules for the evaluation of solvent orientation and bonding. Since the series of alcohols offers a systematic variation in solvent properties, these studies provide substantial insight regarding some of the chemical interactions which can dictate orientation. The development of emersed electrode technologies is also presented as a means to improve selectivity for surface molecular species over bulk molecular species. The utility of this approach is demonstrated for a variety of straight-chain alcohols at both rough and smooth Ag electrodes. Conditions for emersing the molecular interface, intact, under potential control are presented. Finally, double layer capacitance measurements are performed to offer additional insight regarding alcohol solvent structure and interfacial composition as a function of electrode potential. In addition, capacitance-potential plots are used along with the Hurwitz-Parsons analysis to determine absolute surface coverage of Br⁻ as a function of electrode potential. These results are correlated with the Raman spectroscopic results to obtain a consistent model for the structure and composition of the alcohol-Ag electrochemical interface.