Interaction of O2, CO and CO2 with Co films

Metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS(HeI)) and x-ray photoelectron spectroscopy (XPS) were applied to study the interaction of O2, CO and CO2 with Co films at room temperature. The films were produced on Si(100) surfaces under the in situ control of MIES, UPS and scanning tunnelling microscopy (STM). For O2, dissociative adsorption takes place initially and then incorporation of oxygen starts at exposures of ∼5 L. Comparison of the MIES and UPS spectra with those published for CoO shows that near-stoichiometric CoO films can be obtained by co-deposition of Co and O2. The CO is adsorbed molecularly up to a maximum coverage of ∼0.6 monolayer, with the C-end pointing towards the surface. The CO2 adsorption is dissociative, resulting in the formation of Co–CO bonds at the surface. The resulting oxygen atoms are mostly incorporated into the Co layer. For all studied molecules the interaction with Co is similar to that with Ni. Copyright © 2005 John Wiley & Sons, Ltd.