DIRECT DETERMINATION OF MULTIPLE ADSORPTION SITES USING CHEMICAL-SHIFT PHOTOELECTRON DIFFRACTION - SB GAAS(110)/

A direct inversion of experimental energy-dependent photoelectron diff raction data has been used to determine the structure of two inequival ent adsorption sites of Sb at the GaAs(110)-p(1 x 1)Sb surface. Scanne d-energy distributions for each of the two chemically shifted componen ts of the Sb-4d core level were measured and the reconstruction of the se data yields to three-dimensional images of the nearby atoms. Our re sults show that the atomic geometry of the Sh overlayer contradicts va rious models proposed for this surface and are consistent only with th e epitaxial continued layer structure.