Near edge x-ray absorption fine structure study of benzene adsorbed on metal surfaces: Comparison to benzene cluster complexes

Near edge x-ray absorption fine structure (NEXAFS) spectroscopy has been used to study benzene adsorbed on several close-packed metal surfaces [Au(111), Rh(111), Pt(111), and Ru(0001)] under the same experimental conditions. The NEXAFS spectra reveal significant differences with regard to the shapes and positions of resonances and the dichroism observed for the resonance intensities. These differences correlate directly with the binding energy and can be attributed to differences in the electronic coupling of the benzene molecule to the substrate and to adsorption induced changes in the molecular structure of the benzene molecule. A comparison to the NEXAFS spectra recorded for the benzene metal cluster complexes [Ru(eta(6)-C6H6)(CH3CN)(3)](2+) and Ru3(CO)(9)(mu(3):eta(2) eta(2) eta(2)-C6H6) indicates that the mu(3)-arene complex, where the benzene ring is bonded to three metal atoms, can be regarded as a reasonable cluster analog for the adsorption of benzene on the Ru(0001) transition metal surface. (C) 1998 American Vacuum Society.