X-ray emission spectroscopy of (2√3x2√3)R30°CO/Ru(0001):: Comparison to c(2x2) CO/Ni(100) and c(2x2)CO/Cu(100)

The atom specific electronic structure of (2root3x2root3)R30degreesCO on hcp Ru(0001) has been determined with resonantly excited x-ray emission spectroscopy. We find that the general features of the local adsorbate electronic structure are similar to the situation of CO adsorbed on the fcc metals Ni(100) and Cu(100). The interpretation of the surface chemical bond of (2root3x2root3)R30degreesCO/Ru(0001) based on the direct application of the local, allylic model from on-top adsorption on the fcc(100) surfaces Ni(100) and Cu(100) explains many aspects of the surface chemical bond. However, also nonlocal contributions like adsorbate-adsorbate interaction and the deviation from upright on-top adsorption on the Ru(0001) surface influence observables like the heat of adsorption and the Me-CO bond strength. (C) 2004 American Institute of Physics.