Acid-state characterization of water-oxidized alumina films by near-edge x-ray absorption and soft x-ray photoemission
- Cornell Univ., Ithaca, NY (United States)
- Sandia National Labs., Albuquerque, NM (United States)
- Mobil Research and Development Corporation, Paulsboro, NJ (United States)
Hydroxylated alumina films have been synthesized by water oxidation of single crystal Al(110) surfaces. Thermal dehydroxylation results in anion vacancies which produce an Al(3s) defect state 3.5 eV below the conduction band edge. The defect-DOS exhibits a maximum for oxides heated to 648{+-}25 K, which is just where the materials exhibit maximum Lewis acidity with respect to C{sub 2}H{sub 4}. Adsorbed C{sub 2}H{sub 4} produced thermally reactive C{sub 2} species which interact covalently with the defect-DOS and nonbonding O(2p) states from the top o9f the valence band. C(1s) binding energies suggest significant charge transfer which is consistent with a carbenium ion. Ni deposits behave similarly but transfer charge directly to Al species and do not interact with O atoms at the defect site. The defect-DOS is regenerated when the C{sub 2} species decomposes or when Ni migrates thermally through the oxide layer.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 99501
- Report Number(s):
- CONF-941144--; ISBN 1-55899-277-4
- Country of Publication:
- United States
- Language:
- English
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