The structure of the commensurate ($23\times 23$) phase of graphene on Ru(0001) has been analyzed by quantitative low-energy electron diffraction (LEED)-$I(V)$ analysis and density-functional theory calculations. The $I(V)$ analysis uses Fourier components as fitting parameters to determine the vertical corrugation and the lateral relaxation of graphene and the top Ru layers. Graphene is shown to be strongly corrugated by 1.5 Å with a minimum C-Ru distance of 2.1 Å. Additionally, lateral displacements of C atoms and a significant buckling in the underlying Ru layers are observed, indicative for strong local C-Ru interactions.

• Received 31 August 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.136102