PHOTODECOMPOSITION OF 1,1,2-TRICHLOROETHANE - SPECTROSCOPIC EVIDENCE FOR VINYL FORMATION ON PT(111)

High-resolution electron energy loss spectroscopy (HREELS) and tempera ture programmed desorption (TPD) Here applied to the study of 1.1.2-tr ichloroethane adsorbed on Pt(111) and its reaction products. Adsorptio n at 85 K occurred molecularly. as verified by HREELS and TDS measurem ents. Upon heating. the molecule desorbed intact, Irradiation of tile sample with a mercury are lamp resulted in cleavage of the carbon-chlo rine bonds and the formation of a new surface moiety: vinyl. HREELS me asurements of both the deuterated and non-deuterated species confirmed this. Vinyl is stable until 450 K. After flashing to higher temperatu res a new surface species was formed: chlorocarbyne. This species was no longer observed by 600 K. Throughout the entire heating procedure t here was no evidence for the formation of ethylidyne. (C) 1998 Elsevie r Science B.V.