SOFT OXIDATION OF GRAPHITE STUDIED BY XPS AND STM

The modification of the graphite surface after weak oxidation using a nitric acid solution has been studied by X-ray photoelectron spectrosc opy (XPS) and scanning tunneling microscopy (STM). A new corrugation a t the atomic scale has been revealed by STM on the basal planes. It is attributed to the presence, in other respects demonstrated by XPS, of some oxygenated groups created by oxidation and regularly distributed on the surface. This soft oxidation conserves the graphite basal plan es and is interpreted by an oxygen chemisorption on graphite through a bond involving pi electrons of the aromatic cell. Organic groups whic h need dangling sigma bonds to fix on the surface should preferenciall y attach on ridges of large defects.