O2 photodesorption from AuO2- and Au2O2-

Abstract

Using time-resolved photoelectron spectroscopy, the decay channels of AuO2− and Au2O2− following photoexcitation with 3.1-eV photons have been studied. For AuO2−, a state with a rather long lifetime of 30 ps has been identified. Its decay path could not be determined but photodesorption can be excluded. For Au2O2−, the spectra indicate O2 desorption after 3.1-eV photoexcitation on a time scale of 1 ps. While comparing these results on Au n O2− with analogous data on Ag n O2− clusters, a discernible pattern emerges: for dissociatively bound O2(AuO2−, Ag3O2−), there are long-living excited states which do not decay by oxygen desorption, while for molecular chemisorption (Au2O2−, Ag2O2−, Ag4O2−, Ag8O2−), the 3.1-eV photoexcitation triggers fast O2 desorption with a high quantum yield.