THE SURFACE CHEMISTRY OF DIMETHYL DISULFIDE ON COPPER

OCTAVIO JAVIER FURLONG; BRENDAN PAUL MILLER; ZHENJUN LI; JOSHUA WALKER; LUKE BURKHOLDER; WILFRED T. TYSOE

LANGMUIR

AMER CHEMICAL SOC

Año: 2010 vol. 26 p. 16375 - 16380

0743-7463

The surface chemistry of dimethyl disulfide (DMDS) is studied on a Cu(111) single crystal and a polished copper foil in ultrahigh vacuumas 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 ~230Kcauses a small portion of the thiolate species to decompose to form methyl groups adsorbed on the surface. Further heating results in methane and C2 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.