STRUCTURE OF HEPTANETHIOLATE MONOLAYERS ON AU(111) - ADSORPTION FROM SOLUTION VS VAPOR-DEPOSITION

A combined low-energy electron diffraction (LEED) and X-ray photoelect ron spectroscopy (XPS) study on the structural properties of heptaneth iol (C7H15SH) monolayers prepared by either adsorption from the liquid or chemical vapor deposition (CVD) on Au(111) single crystal surfaces has been performed. Deposition from the vapor produces a commensurate c(17 x root 3) superstructure which exhibits a well-defined LEED patt ern. XPS data recorded for these films reveal that the hydrocarbon mol ecules are orientated with their axes parallel to the substrate surfac e. Compared to the more commonly used fabrication of alkanethiolate se lf-assembled films by adsorption from solution the c(17 x root 3) CVD film exhibits a coverage of less than 40%.