Soft X-ray Mg 2p photoemission using synchrotron radiation at moderate spec
tral resolution has been used to investigate the early stages of oxidation
of Mg(0001) with and without preadsorbed Na or K. On the alkali-free surfac
e, some evidence is found for a state characterized by a chemical shift int
ermediate between that of the metallic and oxidic states, but the limited r
esolution and overlapping spin-orbit split surface and bulk metallic compon
ents precludes more thorough characterization. Preadsorbed Na or K enhance
the initial rate of oxidation by approximately a factor of two. It is sugge
sted that the mechanism is an enhancement of the rate of oxygen dissociatio
n. (C) 1999 Elsevier Science B.V. All rights reserved.