Photoemission study of oxygen adsorption on Rb6C60 film surface

X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectr oscopy (UPS) have been used to investigate oxygen adsorption on the surface of Rb6C60 film at room temperature. The results show that the Rb6C60 surfa ce is sensitive to oxygen adsorption. The absorbed oxygen changes the cryst al structure of the film by pulling intercalated Rb atoms to the surface, f orming Rb oxides. An initial rapid oxygen uptake is mainly related to the f ormation of rubidium peroxide (Rb2O2). There exists a strong reaction betwe en C-60 and Rb2O2, leading to the formation of rubidium carbonate (Rb2CO3). At high oxygen exposures, a slow further adsorption of oxygen is associate d with the intensity increases of both Rb2CO3 and rubidium superoxide (RbO2 ) species. (C) 2000 Published by Elsevier Science B.V. All rights reserved.