An Ab Initio Study of Ethyl Xanthate Adsorbed on Ge(111) Surfaces

The interaction between adsorbed ethyl xanthate on a clean Ge(111) surface and a hydroxylated surface was studied, using first-principle density functional theory. Geometrically optimized structures are presented and discussed. Results suggest a bidentate bridging conformation on a clean Ge(111) surface, whereas a monodentate bonding is preferred when the surface is saturated by hydrogen atoms. Then the interaction with a hydroxylated surface was considered. The lowest energy configuration was obtained when xanthate binds with one sulfur to the surface and with the other to an OH group adsorbed on the surface. A marker for this configuration was found in the vibrational spectra at 3200 cm-1. Vibrational frequencies down to 250 cm-1 were calculated and assigned to vibrational modes and presented together with the calculated infrared spectra. The tilt angle of the hydrocarbon chain was also investigated.