EFFECT OF SOLUTION CONDITIONS AND ELECTRODE POTENTIAL ON THE SURFACE ENHANCED RAMAN SCATTERING OF NITROGEN HETEROCYCLES (PYRIDINE, PYRIDINIUM).
Item
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Title
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EFFECT OF SOLUTION CONDITIONS AND ELECTRODE POTENTIAL ON THE SURFACE ENHANCED RAMAN SCATTERING OF NITROGEN HETEROCYCLES (PYRIDINE, PYRIDINIUM).
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Identifier
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AAI8409382
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identifier
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8409382
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Creator
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BERNARD, IRENE.
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Contributor
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Ronald L. Birke | John R. Lombardi
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Date
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1984
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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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pH and chloride effects on the spectrum of pyridine are reported. The concentration of the adsorbed pyridine and pyridinium molecules is heavily dependent on he pretreatment method and chloride concentrations employed. The surface line seen at 237 cm('-1) is a pyridinium chloride-Ag vibration and not a chloride-Ag band since at a pH of 2, pure chloride does not display this band. Also, a chloride concentration study at a fixed pyridinium concentration indicates that at a low chloride concentration, the spectrum is hardly visible. As more of this electrolyte is added, the intensity increases up to a ratio of 1:1 chloride:pyridinium and then there is a decrease, due to desorption from the surface of the ion pair.;At pH = 8, the effects observed on pyridine are the following--the intensity ratio of the 1008 and 1035 cm('-1) modes is nearly independent of the concentration ratio of chloride to pyridine, but highly dependent on the potential. Also, as more chloride is added, the voltage at which a spectrum can be seen becomes more negative, indicating that at a high bulk chloride concentration, the adsorbed halide completely covers the surface, displacing pyridine.;A study of quiniclidine focuses on two degenerate peaks which show drastic changes in their relative intensities on the surface. In contrast with piperidine, the symmetric peaks shows a bigger halide dependence than the asymmetrical one.;Other reported results include SERS of acridine and isoquinoline. Acridine does not show significant changes in the spectrum upon protonation. Also the spectrum in the presence of Br('-) was more intense than in the presence of Cl('-), differing in this from pyridine. Isoquinoline shows the same pH effects as pyridine in terms of the voltage dependence as a function of the halide employed and the behavior of the low lying vibration around 200 cm('-1).;Studies on Hg sols indicate that there is in fact a plasmon which absorbs at 210 nm. However, no SERS was observed, due to the dielectric properties of this metal.
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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
