XPS CHARACTERIZATION OF NI AND MO OXIDES BEFORE AND AFTER INSITU TREATMENTS

The characterization of oxide surfaces is often made by means of the X PS technique: in this paper results obtained by treating nickel and mo lybdenum oxides at a temperature of 523 K, at 10(-4) Pa (in vacuo) and at 10(5) Pa (in hydrogen), are reported. These treatments were perfor med in a reaction chamber and the samples were subsequently analyzed i n the main chamber without exposing them to the atmosphere. The result s indicate that it is possible to completely reduce nickel oxide to me tal by treating it in hydrogen, while the heating in vacuo leaves a fa irly large amount of oxide not reduced on the surface (77.8%, atomic p ercentage). On the other hand, on the two molybdenum oxides (MoO3 and MoO2) it is possible to notice the presence of a large amount of inter mediate not reduced oxides, at 523 K, both in hydrogen and in vacuo.