Associative oxygen species on the oxidized silver surface formed under O-2microwave excitation

The experimental methods of X-ray and ultraviolet photoelectron spectroscop ies (XPS and UPS, respectively) and the quantum mechanical calculations are applied for analysis of oxygen states on the silver oxide surface. At low temperatures (T < 470 K), the silver surface is intensively oxidized by a m icrowave oxygen discharge to form cuprite Ag2O. Two adsorbed oxygen species of the atomic (dissociative) and molecular (associative) nature can be ads orbed on the cuprite Ag2O surface. A comparison of the UPS data and the DFT calculations of molecular models Ag-2-O-2 and Ag-2-O-3 shows that the form ation of ozonide-libe structures is preferable to that of peroxide species. Thermal stability and the reaction probability of the adsorbed states are investigated. (C) 2000 Elsevier Science B.V. All rights reserved.