Surface core-level binding energy shifts for MgO(100)

Theoretical and experimental results for the surface core-level binding energy, BE, shifts, SCLS, for MgO(100) are presented and the anomalous O(1s) SCLS is interpreted in terms of the surface electronic structure. While the Mg(2p) surface BE shifts to a higher value than bulk by approximate to 1 eV as expected from the different surface and bulk Made lung potentials, the O(1s) SCLS is almost 0 rather than approximate to-1 eV, expected from the Made lung potentials. The distortion of the surface atoms from the spherical symmetry of the bulk Mg and O atoms is examined by a novel theoretical procedure. The anomalous O SCLS is shown to arise from the increase of the effective size of surface O anions.