XPS and XAS study of oxygen coadsorbed with a dispersed phase of K on graphite

摘要

The adsorption of O-2 onto a dispersed (low coverage) phase of K on graphite has been characterized by X-ray photoemission and X-ray absorption spectroscopy. We identify two oxygen adsorption phases before physisorbed oxygen appears. The first species dominates at low O-2 exposures whereas the second one, which is probably due to oxygen adsorbed in a superoxo-like configuration (O-2(-delta), delta less than or equal to1), is dominant at higher oxygen coverage. As a function of increasing oxygen dose, we confirm that the charge, initially donated by the potassium adlayer to the graphite, is gradually withdrawn from the substrate. (C) 2001 Elsevier Science B.V. All rights reserved. References: 17