The Influence of Potential on Metal-Adsorbate Structure: Solvent- Independent Nature of Infrared Spectra for Pt(111)/CO
PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
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In-situ infrared spectra are reported in the C-O stretching nu co region for saturated CO adlayers on Pt 111 in four nonaqueous solvents acetonitrile, dimethylformamide, dichloromethane and tetrahydrofuran, each containing tetraalkylammonium cations, over wide electrode potential ranges, ca -2.0 to 1.5 V vs SCE. Notably, the spectral features nu co Frequencies, CO site occupancies, etc are sensitive only to the applied potential, being virtually independent of the solvating medium. Comparisons with spectra obtained in the presence of different cations, and in corresponding aqueous electrochemical and ultrahigh vacuum environments, demonstrate that the adlayer properties are controlled in each case by the surface potential drop across the adsorbate layer.