DEPTH PROFILES OF CONSTITUENT ELEMENTS IN THE SURFACE-LAYER OF PYROGRAPHITE MODIFIED WITH VOCL3

Using scanning tunneling microscopy and angle-resolved x-ray photoelec tron spectroscopy the composition and structure of the surface of pyro graphite modified with VOCl3 in various atmospheres (air, nitrogen, an d helium) have been studied. It is found that the nature of the carrie r gas affects significantly both the thickness of vanadium-oxygen stru ctures and the depth variation in the ratio of oxygen and vanadium con centrations. The thickness of the layer of structures synthesized is s hown to increase in the following order: He< N2 <air. The conclusion i s made that one or two surface monolayers of graphite-like carbon were formed. The STM images obtained are indicative of the formation of su rface structures with periodicity of 0.30-0.32 or 0.40-0.42 nm, depend ing on the synthesis procedure.