Identification of reaction intermediates and products in the dehalogenation of trichloroethene on Cu(110)

The decomposition of trichloroethene, C2HCl3, on Cu(110) has been investigated as a function of temperature by RAIRS, HREELS and TPD. This has provided a detailed identification of intermediate surface species involved in the dechlorination reaction. Multilayers form readily at 85 K, desorbing at 140 K. A weakly perturbed molecular species exists at 150 K that is converted, with increasing temperature, to a CCH intermediate at the surface. This ethynyl intermediate subsequently disproportionates to produce C2H2 and a carbon deposit at the surface. At T>300 K, C2H2 desorption competes with the trimerisation reaction that leads to benzene evolution at 370 K. CI atoms are retained at the surface up to high temperatures. (C) 1999 Elsevier Science B.V. All rights reserved.