Effects of preadsorbed hydrogen on the adsorption of O2, CO and H2O on beryllium

The adsorption of O2, CO and H2O on a hydrogen precovered beryllium surface was studied using direct recoils spectrometry and Auger electron spectroscopy. It was found that preadsorbed hydrogen, in addition to adsorption site blocking, changes the Be electronic structure in a way that hinders the adsorption of O2 and CO on the surface. Apparently, repulsion between the preadsorbed hydrogen and adsorbed oxygen or CO creates depletion zones between them. For oxygen it also promotes agglomeration and penetration into the subsurface and leads to oxide nucleation at lower oxygen overages. For H2O, only a minor delay of adsorption and hydrogen replacement was observed.