VIBRATIONAL DYNAMICS OF CO AT SINGLE-CRYSTAL PLATINUM-ELECTRODES IN AQUEOUS AND NONAQUEOUS ELECTROLYTES

The vibrational dynamics of CO at two electrochemical interfaces is st udied as a function of the electrode potential, for CO/Pt(100) in 0.1M aqueous H2SO4 and CO/Pt(110) in 0.05M C16H36ClNO4 acetonitrile electr olyte. The measured lifetime of similar to 1.7 ps is in line with thos e previously determined for dry CO-metal interfaces. The lifetime appe ars to be independent of the electrolyte composition, and unaffected b y an electrode-potential variation as large as 2 V achieved for the no n-aqueous electrolyte experiment. These measurements suggest that the 2 pi CO acceptor orbital involved in the substrate/adsorbate charge t ransfer process is much broader than 0.8 eV.