Surface-enhanced Raman spectroscopy of bipyridines and phenylpyridines.
Item
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Title
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Surface-enhanced Raman spectroscopy of bipyridines and phenylpyridines.
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Identifier
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AAI9020752
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identifier
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9020752
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Creator
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Diamandopoulos, Panayiotes S.
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Contributor
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Adviser: Thomas C. Strekas
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Date
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1990
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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 | Chemistry, Physical
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Abstract
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Surface enhanced Raman spectroscopy (SERS) using metal colloids has provided a new and much improved approach to the study of condensed phase metal interfaces. The enhancement of the Raman scattered intensity of the analyte upon adsorption on the surface can be up to 10{dollar}\sp 7{dollar}, while scattering from the solvent remains weak or non-observable. Isomeric bipyridines and phenylpyridines that were investigated in this study, were chosen because of their characteristic structural and symmetrical properties. They all possess one sigma electron donor nitrogen on each of their pyridine rings, as well as an extensive {dollar}\pi{dollar} type electron donor system through their aromatic rings. These two electron donor sites can compete for interaction with metal surface during adsorption, thus resulting in different enhancements for the molecules. The metal surface, a silver colloidal suspension, was prepared by the reduction of a silver nitrate solution by sodium citrate. The SERS spectra of these compounds were recorded in the 700-1700 and 2900-3200 cm{dollar}\sp{lcub}-1{rcub}{dollar} regions of the spectrum. The adsorption mode of these compounds on the silver surface was also investigated. According to surface selection rules, when a molecule adsorbs onto the metal surface one of its molecular axes would become the z axis (or normal) with respect to the metal surface. From the molecules studied it was found that the greatest enhancement is observed for those that adsorb on the surface in a perpendicular fashion (along the surface normal). For this type of adsorption the observed SERS enhancement is due to the molecular vibrations that derive their intensity from the {dollar}\alpha\sb{lcub}\rm z\ z{rcub}{dollar} component of the molecular 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.
