Substrate scattering effects in the near-edge X-ray absorption fine structure of Ni(110)-p2mg(2 × 1)-CO

The near-edge X-ray absorption fine structure (NEXAFS) of Ni(110)-p2mg(2 × 1)-CO with titled CO molecules in short-bridge adsorption sites has been studied at the oxygen K edge. An additional structure is observed between the π and σ resonances the energy position of which is different in the 〈100〉 and 〈110〉 azimuths. It is shown that these features cannot be explained by Rydberg transitions, multi-electron excitations or vibrational effects. The analysis of the corresponding surface extended X-ray absorption fine structure (SEXAFS) suggests an assignment to SEXAFS wiggles due to backscattering from substrate atoms.