The effect of potassium on the molecular orientation of CO chemisorbed on Ni(111): An esdiad study

Abstract

Using electron stimulated desorption (ESD) and electron stimulated desorption ion angular distribution (ESDIAD) techniques, we have determined that coadsorbed potassium systematically quenches the O + ion yield from CO on the Ni(111) surface for 1000 eV electron excitation energies. The quenching appears to be a short range K-CO interaction; 3 or 4 CO molecules are affected for each K atom adsorbed on the surface. The quenching effect of K on CO indicates that a significant electronic perturbation of CO is caused by its local interaction with K. This effect prevents ESDIAD observation of the K-quenched CO species. In addition, the CO molecules that are not quenched at a potassium coverage of 0.02 K/Ni exhibit a normally oriented C-O bond similar to that found for CO adsorbed on a K-free Ni(111) surface.