Abstract

The geometric structure of a Co(0001)-(root7 x root7)R19.1degrees-C6H6 surface formed by adsorption of benzene to the saturation coverage at 170 K has been determined by low energy electron diffraction (LEED). The favored model consists of a flat laying, nearly undisturbed benzene molecule, with the hydrogen-carbon bonds bent away from the substrate by 0.3 +/- 0.2 Angstrom. The carbon ring lies at a hcp-site with the two parallel C-C bonds aligned with [1100] direction. Buckling between the inequivalent carbon atoms in the molecular ring is within the experimental uncertainty (0.01 +/- 0.11 Angstrom). The experimental results are supported by density functional calculations.