title: The surface chemistry of dimethyl disulfide on copper.
abstract: The surface chemistry of dimethyl disulfide (DMDS) is studied on a Cu(111) single crystal and a polished copper foil in ultrahigh vacuum as a basis for understanding its tribological chemistry using a combination of temperature-programmed desorption (TPD), reflection-absorption infrared spectroscopy (RAIRS), and X-ray photoelectron spectroscopy (XPS). Low-energy electron diffraction reveals that the polished foil becomes ordered on heating in vacuo and displays identical surface chemistry to that found on the Cu(111) surface. Dimethyl disulfide reacts with the copper surface at 80 K to form thiolate species. Heating the surface to ∼230 K causes a small portion of the thiolate species to decompose to form methyl groups adsorbed on the surface. Further heating results in methane and C(2) hydrocarbon desorption at ∼426 K, due to a reaction of adsorbed methyl species, to completely remove carbon from the surface and to deposit atomic sulfur.
authors.affiliation: Department of Chemistry and Biochemistry, and Laboratory for Surface Studies, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
authors.forename: Octavio J
authors.initials: OJ
authors.lastname: Furlong
authors.forename: Brendan P
authors.initials: BP
authors.lastname: Miller
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Li
authors.forename: Joshua
authors.initials: J
authors.lastname: Walker
authors.forename: Luke
authors.initials: L
authors.lastname: Burkholder
authors.forename: Wilfred T
authors.initials: WT
authors.lastname: Tysoe
mesh_terms: D000327:Adsorption; D003300:Copper / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D004220:Disulfides; C021181:dimethyl disulfide; D003300:Copper