Surface core-level shifts of Ge(100)-2X1 - art. no. 153310

Core-level photoemission spectra of the buckled Ge(001)-2x1 surface taken a t various energies and emission angles are analyzed, using the inelastic me an free path (IMFP) to constrain the intensities of the contributions to th e 3d signal of the first two surface layers and the bulk. This ansatz succe ssfully represents data from the clean Ge(100) surface at all emission angl es and photon energies. The surface core-level shifts of the up-dimer atom, down-dimer atom, and subsurface atom are then found at -442, -183, and +93 meV, respectively. They are in good agreement with the final-state theoret ical calculations by Pehlke and Scheffler [Phys. Rev. Lett. 71, 2338 (1993) ]. The IMFP is 3.5+/-0.2 Angstrom at 26 eV kinetic energy. Furthermore, we found that hulk and surface atoms have distinct spin-orbit splittings of 59 4 and 561 meV, respectively.