Coverage dependent change in orientation for the adsorption of benzyl mercaptan on Au(111)

The self-assembly of monolayers of benzyl mercaptan (benzenemethanethiol, C6H5CH2SH) on Au(1 1 1) at room temperature has been studied by low energy electron diffraction and high resolution electron energy loss spectroscopy (EELS). It was found that the orientation of the molecule depends on coverage with the aromatic ring being parallel to the surface for low coverage and more perpendicular at higher coverage. Low energy electron diffraction indicates a (root7 x root7)R19.1degrees adsorbate structure at saturation coverage. (C) 2004 Elsevier B.V. All rights reserved.