Fundamental studies of the chemisorption of organosulfur compounds on Au(111). Implications of molecular self-assembly on gold surfaces.

Studies of the adsorption of methanethiol and dimethyldisulfide on an Au(111) surface under UHV conditions are described. Both adsorbates bind strongly, with the bonding of the disulfide being greatly favored. It is found that, under these conditions, the disulfide bond is dissociated to give a stable surface thiolate. Adsorption of methanethiol does not involve the cleavage of the S-H bond. The implications of these results for solution adsorption experiments and the thermodynamics characterizing monolayer formation are discussed.