Orientation of Chemisorbed Molecules from Surface-Absorption Fine-Structure Measurements: CO and NO on Ni(100)

Abstract

Surface-absorption fine-structure studies for CO and NO on Ni(100) exhibit two pronounced resonances above the C, N, and O $K$ edges. A strong polarization dependence of these resonances, which correspond to a $\ensuremath{\sigma}\ensuremath{\rightarrow}\ensuremath{\pi}$ discrete absorption and a $\ensuremath{\sigma}\ensuremath{\rightarrow}\ensuremath{\sigma}$ shape resonance, allows the precise determination of molecular orientation. Both molecules are found to be aligned along the surface normal within 10\ifmmode^\circ\else\textdegree\fi{}.