MOLECULAR-BEAM STUDIES OF ALKALI PROMOTION - O2 STICKING ON PT(111) + K

Molecular beam techniques have been used to study the promotion of O2 sticking on a Pt(111) surface due to co-adsorbed K. The results show a complicated dependence of this promotion on K coverage, incident energy and surface temperature, and cannot be interpreted in terms of simple one-dimensional charge-transfer models often used to rationalize alkali promotion. There is evidence that molecular precursors, including that due to a physisorbed species, play a dominant role in the sticking of O2 on the K-modified Pt(111) surface.