HYDROXYLATION OF MOLECULARLY ADSORBED WATER AT AG(111) AND CU(100) SURFACES BY DIOXYGEN - PHOTOELECTRON AND VIBRATIONAL SPECTROSCOPIC STUDIES

Molecular water adlayers at Ag(111) and Cu(100) surfaces undergo facile hydroxylation on exposure to dioxygen at low temperatures. XP and HREEL spectra distinguish between OH(a), H2(a) and O-2(a) and in the case of Ag(111) surfaces establish that O-2(a) is the reactive species. At Cu(100) the evidence points to a transient O-2(s) species. These results establish that preadsorbed chemisorbed oxygen adatoms are not a pre-requisite for the activation of molecularly adsorbed water and provide further evidence for the high chemical reactivity of dioxygen species present transiently in the disociative chemisorption of oxygen at metal surfaces. © 1990.