Use of sum frequency generation vibrational spectroscopy to monitor the structure of adsorbates with changing electrode potential

COLL 72

Gabor A. Somorjai and Keng Chou. Department of Chemistry, Lawrence Berkeley National Laboratory and University of California, Berkeley, Berkeley, CA 94720-1460
Platinum single crystal electrodes were employed to monitor the structures of adsorbed CO and acetonitrile as a function of electrode potential. Molecular CO remains unchanged up to its oxidation potential while acetonitrile changes orientation. Combined cyclic voltammetry and SFG studies show the importance of carrying out SFG measurements faster than the rate of potential sweep. Glassy carbon electrode was used to monitor the change of structure of adsorbed phenylalanine with changing potential. SFG studies are powerful to monitor adsorbed layers, their structure and chemistry as a function of electrode potential to provide molecular information at electrochemical interfaces.