EVOLUTION OF K-GRAPHITE, RB-GRAPHITE AND CS-GRAPHITE INTERCALATION COMPOUNDS SURFACES UNDER CONTROLLED OXIDIZATION - AN XPS STUDY

The evolution of XPS spectra of K-, Rb- and Cs-GICs of stage 1,2 and 3, when their cleaved surfaces are submitted to well controlled oxidization is presented. The results confirm the existence of the alkali surface species previously observed on clean surfaces and the surface evolution under oxidization is described through diffusion of the metallic atoms from inner interlayers onto the surface. A clear explanation may, thus, be given for the apparent superficial enrichment in alkali claimed in various previous papers.