Initial oxidation of the Al(001) surface: Self-consistent electronic structure of clean Al(001) and Al(001)-p(1 x 1)O
Changes due to the initial oxidation of Al(001) were determined from results of the first self-consistent thin-film calculations for the clean Al(001) surface as well as Al(001)-p(1 x 1)O. For clean Al(001), surface state-surface resonance bands obtained for a nine-layer slab were found to be in good agreement with photoemission measurements and our earlier non-self-consistent results; its work function (4.7 +- 0.1 eV) is in good agreement with the Grepstad et al. experimental value (4.41 +- 0.03 eV); no surface core-level shift was found in agreement with a recent photoemission measurement; finally, the absence of an increased broadening in the surface Al(2p) core level is discussed. For the nine-layer Al(001) plus O slab, the calculated reduction in the work function (0.6 eV) is in good agreement with the experimentally determined reduction (0.5--0.8 eV). Prominent O(2p) peaks in the surface layer density of states at -8.0 and -10.0 eV below E/sub F/ are in good agreement with photoemission measurements. Structure at 1.0 and 1.8 eV above E/sub F/, due to O-induced surface resonance states, are related to interface states observed by surface soft-x-ray absorption spectroscopy. The overall bonding is found to be ionic in character with charge transfer onto the O atoms. A surface core-level shift of 1.5 eV to greater binding energy is found for the surface Al atom, in excellent agreement with the Eberhardt and Kunz 1.4-eV Al(2p) shift. It is concluded that in the initial stages of oxidation a substantial number of O atoms are chemisorbed into coplanar, fourfold hollow sites, which is consistent with a recent extended-appearance-potential-fine-structure measurement for the Al--O bond length and an earlier self-consistent cluster calculation.
- Research Organization:
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60201
- OSTI ID:
- 6544604
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 23:8; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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