Structure and properties of 1,4-benzenedimethanethiol films grown from solution on Au(1 1 1): An XPS and NEXAFS study

Core level photoemission and X-ray absorption at the carbon C 1s edge are applied to the study of chemisorption of 1,4-benzenedimethanethiol molecules on Au(1 1 1) and to investigate the effect of the solvent used to prepare the organic films. 1,4-Benzenedimethanethiol films were prepared in polar and non-polar solvents, i.e. ethanol, methanol and n-hexane. 1,4-Benzenedimethanethiol molecules are anchored to the substrate through a single S-Au bond; the molecules in the films tend to assume an upright orientation, the aromatic ring resulting tilted towards the direction perpendicular to the substrate plane. The films present an effective thickness corresponding to more than a single layer. Only small differences are observed among behaviours in different solvents. It is concluded that the final properties and conformation of the 1,4-benzenedimethanethiol films are largely determined by the reciprocal interactions between the molecules and with the substrate.