Photoreactions of adsorbed CH3Br on Pt(111)

Abstract

Wavelength-dependent fragmentation cross-sections for chemisorbed CH3Br on Pt(111) have been quantitatively determined in the ultraviolet region using thermal desorption spectroscopy to monitor the formation of the photoproducts. In comparison to the absorption spectrum of the free CH3Br molecule in the gas phase, a red shift of about 100 nm and a considerable broadening of the curve is observed on the surface. Two different reaction channels for the photo-induced reaction have been identified. In addition to the cleavage of the C-Br bond, resulting in chemisorbed CH3 and Br, HBr has also been identified as a reaction product. Through a characterization of vibrations using high resolution electron energy loss spectroscopy, a C3v configuration can be assigned to the adsorbed CH3 group on the surface. © 1990.