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-C₁ and C-C₂ distances of 1. 45 0. 03 and 2. 50 0. 03, respectively. The graphite overlayer floats at 2. 80 0. 08 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.