Generation and Reaction of Vinyl Groups on a Cu(100) Surface

The adsorption and reactions of vinyl bromide and vinyl iodide on a Cu(100) surface have been studied by temperature-programmed desorption in conjunction with near-edge X-ray absorption fine structure (NEXAFS) and work function change measurements. Vinyl bromide adsorbs molecularly on the surface at 100 K. The polarization dependence of the π*CC resonance indicates that the molecules lie with their π bond within 28 ± 5° of parallel to the surface. Upon heating, both vinyl bromide and vinyl iodide decompose to generate surface vinyl groups, which adopt a tilted orientation on the surface. Both the molecular halides and the surface vinyl groups show a splitting of the π*CC NEXAFS resonance due to the inequivalence of the carbon atoms in these species. The position of the σ*CC shape resonances for these species indicates little change (