Different oxidation states of polycrystalline molybdenum treated by O2-plasma or O2-ion bombardment

Abstract The oxidation of Mo polycrystalline foils at room temperature, through O 2 -ion bombardment and a reactive O 2 plasma studied by XPS and AES, is reported. Samples bombarded with O 2 ions showed Mo 3d XP spectra with two broad peaks, which can be deconvoluted with standard spectra of Mo 0 , a small contribution of Mo 6+ and a residue assigned to Mo 4+ and Mo n + with n 0 , Mo 6+ , a small contribution of Mo 4+ and Mo n + . In the region of the Mo MNN Auger transitions (150–240 eV), three new peaks appeared upon oxidation, at ∼5 eV lower kinetic energy than in Mo 0 . The relative intensities within each pair of peaks at 160, 186, and 221 eV depend on the oxidation method, i.e. on the kind of oxide formed.