AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM6
Initial Stages of Al(111) Oxidation by Oxygen - Temperature and Surface Morphology Effects

Wednesday, November 4, 1998, 10:00 am, Room 309

Session: Gas-Surface Dynamics
Presenter: V. Zhukov, University of Pittsburgh
Authors: V. Zhukov, University of Pittsburgh
I. Popova, University of Pittsburgh
J.T. Yates, Jr., University of Pittsburgh
Correspondent: Click to Email
The mechanism of oxygen chemisorption and the oxidation of aluminum is again of interest in the light of recent STM studies on Al(111).@footnote 1,2@ We have used X-Ray Photoelectron Spectroscopy (XPS) and High Resolution Electron Energy Loss Spectroscopy (HREELS) to carefully examine the temperature dependence of the Al(111) oxidation kinetics in the range 95-773 K. The onset of oxide formation was detected near 473 K at the low oxygen coverages investigated here. Both activated and non-activated adsorption channels have being found depending on surface temperature and the degree of oxide formation, causing nonmonotonic behavior of the sticking coefficient versus temperature. These results are discussed in terms of a one-dimensional potential energy diagram. Surface defects along with the presence of the oxide structures have been found to influence the kinetics of O@sub 2@ adsorption. The importance of careful surface preparation and smooth surface morphology for the reproducible adsorption measurements are demonstrated in this work. Coverage sensitive HREELS measurements are highly dependent upon surface conditions, and these results may rationalize contradictions present in the literature. Work supported by AFOSR. @FootnoteText@ @footnote 1@H. Brune, J. Wintterlin, J. Trost, G. Ertl, J. Wiechers, R.J. Behm, J. Chem. Phys., 99 (1993) 2128. @footnote 2@J. Trost, H. Brune, J. Wintterlin, R.J. Behm, G. Ertl, J. Chem. Phys., 108 (1998)1740.