Abstract
We have performed high resolution x-ray photoemission spectroscopy experiments on the Ru(0001) surface, both clean and covered with well-defined amounts of oxygen up to 1 monolayer coverage. For the clean surface we detected two distinct components in the Ru core-level spectra, for which a definite assignment was made using the high resolution angle-scan photoelectron diffraction approach. For the and oxygen structures we found Ru core-level peaks that are shifted to higher binding energies by up to 1 eV. Very good agreement with density functional theory calculations of these surface core-level shifts (SCLS’s) is reported. The overriding parameter for the resulting Ru SCLS’s turns out to be the number of directly coordinated O atoms. Since the calculations permit the separation of initial and final state effects, our results give valuable information for the understanding of bonding and screening at the surface that is not accessible in measurements of the core-level energies alone.
- Received 7 November 2000
DOI:https://doi.org/10.1103/PhysRevB.63.205419
©2001 American Physical Society