Surface Reactions of Ethyl Groups on Clean and O-Modified Ru(001)

The surface reactions of C2H5 species produced by thermal and UV photon-induced dissociation of C2H5I have been followed by means of temperature-programmed desorption and X-ray photoelectron spectroscopy. Cleavage of the C−I bond begins at 130 K on the clean surface. The primary products of thermal dissociation are adsorbed C2H5 and I. C2H5 groups take part in hydrogenation/dehydrogenation reactions forming C2H6 in gas-phase and adsorbed ethylidyne (CCH3) on the surface. Preadsorbed O(a) exerts a significant stabilization influence on the dissociation and the desorption of the parent molecule. In its presence the amount of CCH3 decreases and C2H4 appears in the desorbing products. In addition, oxygen atoms react with C2H5 to give diethyl ether and, at higher coverage, acetaldehyde. The decomposition of CCH3(a) on the O-presaturated sample produces carbidic deposits (C, CHx), which react with oxygen to form CO. UV illumination enhances the dissociation of the C−I bond and consequently the formation of CCH3...