Coadsorption of samarium with oxygen on the molybdenum (2 1 1) surface

Samarium atoms exist in two different electronic configurations, namely, divalent (Sm2+) and trivalent (Sm3+). Up to now, those two electronic configurations have been connected with the existence of Sm atoms in different valence states. Recent theoretical calculations performed by Yakovkin show that both electronic configurations have similar LDOS around the Fermi level, and as a result, should give a similar photoelectron emission in the valence band region, which was identified earlier as the emission from the Sm2+ state. The Sm3+ signal in photoelectron emission could originate from contaminations of Sm by other elements, e.g. oxygen. To check the influence of O on the electronic structure of Sm, the XPS experiments of coadsorption of O and Sm have been performed.