Modification of surface-state dispersion upon Xe adsorption: A scanning tunneling microscope study

The modification of the surface electronic structure by an adsorbate is measured quantitatively with scanning tunneling microscopy and spectroscopy for the first time. The standing wave of the Cu surface-state electrons is utilized to probe the subtle change in the electronic structure on the Xe-covered Cu(111). The observed Fermi wavelength on the Xe-covered surface is longer by 15% than on the bare Cu surface. The change upon Xe adsorption is explained with the observed modified dispersion of the Cu surface state; upward shift by (130±20) meV with almost same effective mass.