AU-STEP ATOMS AS ACTIVE-SITES FOR CO ADSORPTION ON AN AND BIMETALLIC AU PD(111) SURFACES/

In a combined variable temperature STM-HREELS study we could identify Au edge atoms in the first, second and higher Au layers on a Pd(111) s ubstrate as sites of a strongly enhanced Au-CO interaction compared wi th CO adsorption on the respective terrace sites. CO molecules adsorbe d on these Au edge atoms give rise to a C-O stretch frequency of 263 m eV, indicative of linearly bound CO. Adsorption on Au terrace sites is not observed at 110 K. The increased Au-CO interaction is attributed to a modification in the electronic properties of Au edge atoms, relat ed to their reduced coordination.