WORK FUNCTION VARIATION IN METALLIC ATOM CHEMISORPTION

The work function variations in metallic atom chemisorption on metals are qualitatively described. These variations are caused by two effects: (i) increase of positive charge on rough single crystal planes due to flattening the planes by adatoms, and (ii) shift of the valence and electronic affinity levels of adatoms caused by the presence of the metal surface. It was shown that the effect (i) causes an initial increase of work function versus coverage until all the valleys" of the rough plane are filles up with adatoms. The adsorption on flat or flattened planes is connected with the effect (ii) which leads to a decrease or increase of work function depending on whether the adsorption is of the catonic or anionic type. © 1979."