  Resonance anomalous surface x-ray scattering (RASXS) technique was applied to
electrochemical interface studies. It was used to determine the chemical states
of electrochemically formed anodic oxide monolayers on platinum surface. It is
shown that RASXS exhibits strong polarization dependence when the surface is
significantly modified. The polarization dependence is demonstrated for three
examples; anodic oxide formation, sulfate adsorption, and CO adsorption on
platinum surfaces. s- and p- polarization RASXS data were simulated with the
latest version of ab initio multiple scattering calculations (FEFF8.2).
Elementary theoretical considerations are also presented for the origin of the
polarization dependence in RASXS.
