The surface core-level shifts of clean and adsorbate-covered Pd(110) have been measured with use of synchrotron radiation. The largest shift of 0.98 eV occurs for a CO-covered surface, and smaller shifts are observed for the oxygen-covered and clean surfaces. The results are compared with values predicted using a Born-Haber cycle, and good agreement is found. Initial-state charge-transfer effects do not dominate the shifts, but instead the shifts are determined by a mixture of initial- and final-state effects. Through the Born-Haber cycle, final-state effects for adsorption on a metal of atomic number Z are associated with the heat of adsorption on the Z+1 element.

• Received 3 December 1990

DOI:https://doi.org/10.1103/PhysRevB.43.14385