CORE-LEVEL SHIFTS ON CLEAN AND ADSORBATE-COVERED SI(113) SURFACES

The silicon 2p core level was investigated on the Si(113) surface usin g angle-resolved UV photoelectron spectroscopy and synchrotron radiati on. For the clean 3 x 2 reconstructed Si(113) surface several surface core-level shifts are observed, two of them shifted by 640 meV to lowe r and 760 meV to higher binding energies, respectively. They are attri buted to adatomlike and dimerlike atoms, the main constituents in the Si(113) 3 x 2 surface structure. A broad component close to the bulk e mission is found and is assigned to the other atoms in the two topmost surface layers that are slighty shifted from their bulk position with in the reconstruction. By adsorption of atomic hydrogen, these surface components can be quenched and others can be created. Monohydride and dihydride phases are identified.