The surface core-level shift of the Nb(110) surface

The surface core level shift (SCLS) of the Nb(110) surface has been determined by means of high resolution core level photoelectron spectroscopy of the Nb 3d5/2 core level. A SCLS of (180 ± 15) meV towards higher binding energy with respect to the bulk component was estimated by curve fitting of Nb 3d5/2 core level spectra taken using several photon energies.The sign of the SCLS agrees with recent ab initio calculations including both initial- and final-state effects, but the shift is significantly smaller than predicted in these calculat ions.