SURFACE RAMAN SPECTROSCOPIES OF THE THREE REDOX FORMS OF METHYLVIOLOGEN AND 4,4'-BIPYRIDINE.
Item
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Title
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SURFACE RAMAN SPECTROSCOPIES OF THE THREE REDOX FORMS OF METHYLVIOLOGEN AND 4,4'-BIPYRIDINE.
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Identifier
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AAI8708303
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identifier
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8708303
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Creator
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LU, TIANHONG.
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Contributor
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Ronald L. Birke | John R. Lombardi
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical
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Abstract
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The electrochemistry of methylviologen and 4,4'-bipyridine on polished and roughened Ag electrodes was studied. The electrochemical behavior of the two compounds on the polished Ag electrode is similar to that on the Hg electrode. However, on the roughened Ag electrode obvious differences were observed. Adsorption peaks for both compounds on the roughened Ag electrode were observed in cyclic voltammograms. Unstable reduction intermediates appear to be stabilized by the roughened Ag electrode.;The surface Raman spectra of the three redox forms of methylviologen and 4,4'-bipyridine were studied. It was found that when the two compounds are electrochemically reduced on the roughened Ag electrode the surface Raman spectra are often a superposition of the surface enhanced Raman spectrum and resonance Raman spectrum and/or normal Raman spectrum of their reduction products. These Raman spectra can be clearly separated and shown to originate from different redox forms of the two compounds.;The intensity-potential profiles for surface enhanced Raman scattering of some molecules on the roughened Ag electrode were studied. The shape of the experimental profiles can be fit very well with the calculated curves from our charge transfer theory indicating that the intensity-potential profile is mainly related to the Raman polarizability of the molecule-metal system. However, sometimes the profile can be influenced by other factors such as electrode reaction, surface coverage and selfabsorption of absorbed molecules. Therefore, when the calculated curve can not fit with the experimental profile there must be a factor which plays a more important role in the intensity-potential profile than that of Raman polarizability.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
