STRUCTURE AND VIBRATIONAL PROPERTIES OF METHANETHIOLATE ADSORBED ON SILVER

The adsorption of methanethiolate on a silver surface has been investigated by surface-enhanced Raman spectroscopy. Two distinct CS stretching bands were observed, one being favorable at submonolayer coverages and the other at the full coverage limit. Results of ab initio molecular orbital calculations imply that the former band is attributable to the thiolate species adsorbed on a multiple site such as the bridge or the four-fold site, and the latter to that adsorbed on the on-top site. Calculated results also suggest that the observed CS stretching band of the thiolate anion in solution is blue-shifted compared with that in the gas phase owing to the hydration of the anion in solution.