Structure of graphitic carbon on Ni(111): A surface extended-energy-loss fine-structure study

The structural parameters of the graphitic carbon overlayer on a Ni(111) substrate has been determined by using surface extended-energy-loss fine-structure spectroscopy. We find that graphitic carbon is very similar to a graphite single-crystal plane, but slightly expanded (∼2%), with C-${\mathrm{C}}_1$ and C-${\mathrm{C}}_2$ distances of 1.45 ± 0.03 and 2.50 ± 0.03 Å, respectively. The graphite overlayer floats at 2.80 ± 0.08 Å above the Ni(111) face. The C-Ni interaction is strong enough to force the overlayer in registry with the substrate. However, we find that the Ni-Ni distance remains identical, showing that the substrate is not affected by the growth of the graphitic overlayer.