The operation of the “metal-surface selection rule” on the vibrational spectra of species adsorbed on supported copper particles

Abstract

The adsorption of CO and ethylene on ZnO-supported copper particles has been studied by infrared transmission spectroscopy. Two chemisorption stages are shown, one at 300 K giving rise to an “on-top” chemisorbed species; a second at 77 K giving rise to a chemisorbed species IR inactive for the metal surface selection rule operation. Adsorption of CO N 2 O mixtures gives rise to a formate and to a carbonate species adsorbed on metal particles, both with a symmetrical bidentate structure (C 2v or C s), as revealed by the inactivity of the ν asym (OCO) mode, as a consequence of the surface selection rule. Ethylene is adsorbed weakly, π-bonded parallel to the metal surface, with a local symmetry C 2v.