Low energy alkali ion scattering from a clean and adsorbate covered Mo(001) surface

Low energy alkali ion scattering has been applied to study the interactions of oxygen and carbon with Mo(001). Qualitative interpretation of the K+ energy distributions, obtained from a surface which contains about 0.7 monolayers of oxygen, indicates that the oxygen is located in the four-fold site of an unreconstructed surface. CO and C2H4, which also adsorb dissociatively, yield very similar ion energy distributions indicating that also for C and for mixed C and O sub-monolayers, the adatoms occupy four-fold sites. Comparison of the experimental K+ energy distributions with those obtained by computer simulation further strengthens this conclusion. Analysis of the energy distributions and also of the dependence of Li+ scattering upon polar incidence angle, yields a value of 0.3 A for the height of the oxygen atoms. (orig.)