Chemistry of chloroethylenes on Cu(100): Bonding and reactions

[摘要] The bonding and reactions of chloroethylenes (vinyl chloride, trans- and cis-dichloroethylene, trichloroethylene) on a Cu(100) surface have been investigated by temperature-programmed desorption and reaction, near-edge X-rap absorption fine structure (NEXAFS) studies and measurements of changes of the surface work function. The monolayer molecules adsorb molecularly intact at 95 K via pi coordination. The molecules orient with their molecular planes parallel to the surface with little increase (<0.02 Angstrom) in the C-C bond distance compared with the gas phase values. The degree of thermal dissociation increases with the extent of halogenation, and no chlorine is present in the hydrocarbon reaction products liberated from the surface. Both cis- and trans-1,2-chloroethylene produce acetylene and a small amount of benzene, while dissociation of trichloroethylene generates acetylene and deposits a carbon residue on the surface. Vinyl chloride desorbs from Cu(100) without reaction. (C) 1997 Elsevier Science B.V.

[发布日期] 1997-05-15

[关键词] alkenes;chemisorption;copper;halides;near edge extended X-ray absorption fine structure (NEXAFS);surface chemical reaction;thermal desorption spectroscopy;work function measurements