SURFACE ENHANCED RAMAN SPECTRA OF MOLECULES ADSORBED ON SILVER ELECTRODES.
Item
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Title
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SURFACE ENHANCED RAMAN SPECTRA OF MOLECULES ADSORBED ON SILVER ELECTRODES.
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Identifier
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AAI8103914
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identifier
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8103914
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Creator
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BUNDING, KATHRYN ADELE.
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Date
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1980
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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, Physical
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Abstract
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The surface enhanced Raman spectra of 2-, 3-, and 4-methylpyridines on silver electrodes are reported and the vibrations assigned. Vibrational modes with dipolar components in the molecular plane and perpendicular to the surface are enhanced more than those in the molecular plane and parallel to the surface while vibrations out of the molecular plane and parallel to the electrode are also enhanced. Unless the molecules are tilted more than 45 degrees, these latter results are inconsistent with theories of surface enhancement which depend on dipole imaging.;The surface enhanced Raman spectrum of 2,6-lutidine on a polycrystalline electrode was investigated to determine the effect of bulky groups adjacent to the nitrogen on the spectrum. The observation of an Ag-N stretch and small shifts of the methyl vibrations on the surface lead to a model of the molecule-surface interaction. If the molecule is adsorbed on a (100) or (110) face, surface roughness on an atomic scale is required to explain the observations. If the molecule is adsorbed on a (111) face, no surface roughness need be invoked. In either case a metal-nitrogen bond somewhere between the van der Waals (physisorbed) and covalent (chemisorbed) limits is indicated.;The electrochemical reduction of 4-acetylpyridine was investigated using SERS as an application of this new phenomenon that allows observation of monolayers on surfaces to the study of electrochemical reactions. The SERS of the starting material, 4-acetylpyridine, were taken at several different potentials and also in deuterated water. The absence of the water stretching lines in spectra which are more intense indicates these are not enhanced. The possible products, 2,3-bis-(4-pyridyl)-2,3-butanediol, 4-(1-hydroxyethyl)pyridine and 4-ethylpyridine were examined with SERS at -1.14 V. A synthesis of 4-(1-hydroxyethyl)pyridine is reported. Attempts to reduce 4-acetylpyridine completely on the silver electrode failed. The spectra of 4-acetylpyridine taken at potentials below the reduction potential show remarkable shifts in band intensity that may be indicative of bonding to the electrode through different atoms.
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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
