COLL 214 |
| Trends in adsorption properties of a series of closely related aromatic compounds including the ortho-, meta-, and para- isomers of the nitrophenols, aminophenols, nitrobenzoic acids, aminobenzoic acids, hydroxybenzoic acids, nitroanilines, and various halogenated benzoic acids were investigated with surface-enhanced infrared absorption (SEIRA) and surface-enhanced Raman spectroscopy (SERS) via adsorption of the individual isomers on vacuum-deposited Ag films and on Ag powders of varying physical dimensions. Studies were further augmented with thermal desorption spectroscopy (TPD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and surface area analysis. As expected, a series of vibrational and/or TPD spectra as a function of increasing coverage of the individual isomers on the Ag films/powders is highly dependent on the strength of adsorption versus intermolecular attraction as well as average particle size within the Ag films/powders. Specific intermolecular interactions appear to be dominated by either classic hydrogen-bonding or strong interactions between individual oxygen or nitrogen atoms within a substituent group of one molecule with an aromatic hydrogen on an adjacent molecule. Adsorption properties often were seen to vary considerably among individual isomers of an isomeric set. Large changes in adsorption characteristics were also documented as a function of adsorption solvent polarity. |
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Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster
Division of Colloid & Surface Chemistry |