The reflection anisotropy spectroscopy of the Au(1 1 0) surface structures in liquid environments

Abstract

The reflection anisotropy (RAS) profiles of the Au(1 1 0)-(1 × 1), (1 × 2) and (1 × 3) surface structures in electrochemical environments are shown to arise mainly from surface dipole transitions directed along the principal axes of the Au(1 1 0) surface. There are weak contributions to the RAS profiles of the Au(1 1 0)-(1 × 1) and (1 × 3) surfaces in the region of 4.0 eV which probably arise from (1 1 1) facets that are either intrinsic to the surface structures or are associated with steps. A transition involving a surface state just above the Fermi level, EF, contributes to the RAS profiles of the (1 × 2) and (1 × 3) surfaces but not to the RAS profile of the (1 × 1) surface. A strong feature at 2.5 eV in the RAS profiles of the Au(1 1 0)-(1 × 1) and (1 × 2) surfaces is attributed to a transition in the vicinity of the L point of the Brillouin zone between the 5d band and the band at EF. It is argued that the applied potential of −0.6 V, which creates the Au(1 1 0)-(1 × 3) surface, lifts EF above the band causing it to become occupied and quenching this contribution to the RAS profile.