CEELS as a Probe of the Carbide to Graphite Transformation on Ni
GEORGE WASHINGTON UNIV WASHINGTON DC DEPT OF CHEMISTRY
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Recent effective medium theory calculations indicate that a nucleation step must be involved in the carbide to graphite transformation on Ni, and that vertical C2 may be a precursor to this nucleation step. A similar nucleation site could also be involved in diamond formation on metals. We interpret previously published C K edge CEELS and NEXAFS data for carbonNi between 500-700K. We make comparison with theoretical DOS calculations, and utilize CEELS angle dependencies to assign features and determine bond orientations on the surface. The results confirm that horizontal Cn, most likely C2, exists on the surface up 600K, but that at 620K, some of the species flip up.
- Physical Chemistry