Al Kα and Cu Kα1 excited XPS of vanadium oxide and VF3 powders: Measurement of the V 1s - KLL Auger parameters

Al Kα (hν = 1486.6 eV) excited XPS shows that powder samples of V2O3, V2O5 and VF3 are surface contaminated and that the V2O3 can be cleaned by heating in vacuum at 400 °C. The greater sampling depth of Cu Kα1 (hν = 8047.8 eV) excited XPS allows measurement of the bulk V 1s - KL2L3 Auger parameters (APs) for these materials. The APs of VF3 and V2O5, relative to V metal, fall into the range of values expected for metal fluorides and oxides with non-local final state core-hole screening, whereas the AP of V2O3 is significantly closer to that of V metal. We ascribe this to a greater final state valence orbital occupation following photionisation in V2O3, part of which results from metal-like screening.