The chemisorption and reaction of trans-dichloroethene on Cu(110) have been
investigated by high-resolution electron-energy-loss spectroscopy (HREELS)
as a function of coverage and temperature. At 135 K, both physisorbed and
chemisorbed trans-dichloroethene are present. Heating to 200 K leads to the
formation of acetylene and of a partially dehalogenated intermediate speci
es. By 300 K, the acetylene trimerises to form adsorbed benzene at the surf
ace. Adsorption of trans-dichloroethene at 300 K produces benzene directly.
Evidence of C-Cl cleavage at temperature as low as 220 K is clearly marked
by the emergence of very intense Cu-Cl stretching vibrations which remain
even after further heating up to 570 K.