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

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, E F, 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 [Formula: see text] band at E F. It is argued that the applied potential of  -0.6 V, which creates the Au(1 1 0)-(1  ×  3) surface, lifts E F above the [Formula: see text] band causing it to become occupied and quenching this contribution to the RAS profile.