The interaction of oxygen molecules with iron films studied with MIES, UPS and XPS

X-ray Photoelectron Spectroscopy (XPS), Metastable Induced Electron Spectroscopy (MIES) and Ultraviolet Photoelectron Spectroscopy (UPS) were applied to study the interaction of oxygen molecules with iron films. Supplementarily, iron oxide was investigated for comparison. With XPS from the Fe 2p(3/2) range contributions of metallic Fe as well as Fe2+ and Fe3+ can be distinguished. During the interaction with oxygen an oxide film is formed on the iron surface. Nevertheless, XPS still shows metallic contributions even for a surface which is saturated with more than 10(4) L The oxide film hinders the dissociation of further impinging oxygen molecules. The interaction of He* atoms with iron oxide surfaces during MIES is dominated by Auger Neutralization. This surprising result follows from the high work function and the fact that intrinsic defects result in a Fermi level pinning to the conduction band. (C) 2010 Elsevier B.V. All rights reserved.