ABSTRACT
The rates of gas-carbon reactions reported in the literature have been measured mostly by thermogravimetric techniques and by evolved gas analysis. Optical as well as scanning electron microscopy do not yield kinetic data on the truly atomic scale. To achieve this resolution, the etch-decoration electron microscopy technique was developed by Hennig. The two basic principles utilized by Hennig for the etch-decoration technique are the high anisotropy of reactivity of graphite on different crystallographic faces and the ability of the crystal edges to trap and nucleate gold. The work done by Hennig and others preceded the commercialization of the scanning electron microscopy, and was thereby limited to transmission electron microscopy. In the TEM studies, a monolayer of gold is enough to produce resolved nuclei decorated on the steps. The active sites on carbon for gas-carbon reactions under normal conditions are the atoms with a free sp2 electron, which are the surface atoms located on edges and defects.
