Chemisorption and the initial stage of oxidation on Mn

Abstract

Chemisorption of O 2, CO, and N 2 on clean manganese has been studied by the techniques of X-ray and UV photoelectron spectroscopy (XPS and UPS) and active ion bombardment and modeled by means of the empirical bond energy-bond order (BEBO) approach. O 2 adsorbs dissociatively and the initial monoxide formation begins at 2 L exposure. MnO is identified by the transition of the itinerant Mn 3d metallic band to the localized discrete ionic 3d state of Mn 2+ and by the splitting of the Mn 2p 1 2 , 3 2 core lines into two components. CO adsorbs in both the dissociative and molecular forms, with the two species co-existing on the surface and distinguishable by the atomic or molecular nature of the valence states and the splitting of the O 1s and C 1s core lines. N 2 adsorbs dissociatively and only after a small activation energy is supplied, e.g., by means of bombardment with N 2 +. The BEBO model is in agreement with and provides an interpretative approach to the chemisorption results.