Adsorption of thiolates to singly coordinated sites on Au(111) evidenced by photoelectron diffraction

The adsorption structure of methylthiolate (CH3S) adsorbed on Au(111), a long-standing controversial issue, has been unambiguously determined by scanned-energy and scanned-angle S 2p photoelectron diffraction. The methylthiolate molecules are found to occupy atop sites with a S-Au distance of 2.42 +/- 0.03 Angstrom. The angular distribution of the S 2p photoelectrons due to forward scattering reveals that the S-C bond is inclined by approximately 50degrees from the surface normal towards both the [(2) over bar 11] and [(1) over bar2 (1) over bar] (nearest-neighbor thiolate) directions.