OBSERVATION BY SCANNING-TUNNELING-MICROSCOPY OF THE MORPHOLOGY CHANGEOF PT HOPG AFTER NO-CO REACTION/

We performed STM experiments to investigate the effects of NO-CO react ion the morphology change of Pt deposited on a HOPG surface. The gasif ication reaction on the Pt/HOPG resulted in straight channels, multidi rection channels, and circular monoatomic step pits on the basal plane . We have observed more channel formation than pit formation in the pr esence of platinum particles, suggesting that catalyzed gasification i s much faster than noncatalyzed gasification reaction. The observed ch anneling structure was found to be 3 to 8 monolayers deep, and is due to NO-CO reaction at higher temperature at which Pt particles attack t he edges and steps of the basal plane of graphite. The unique ability of STM technique was used to resolve atomic structure of 3 to 8 monola yers deep inside channel. The corrugation width of adjacent hexagons w as found to be 2.5 angstrom, which is in good agreement with the C-C i nteratomic distance in the literature.