Acid-site 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 Corp., 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. A maximum in the defect-DOS occurs for oxides heated to 350 to 400C, which is where the materials exhibit maximum Lewis acidity with respect to C{sub 2}H{sub 4}. Adsorbed C{sub 2}H{sub 4} produces thermally active C{sub 2} species which interact covalently with the defect-DOS and nonbonding O(2p) from the top of the valence band. C(1s) binding energies suggest significant charge transfer which is consistent with a carbenium ion. Ni evaporated onto the surface, however, transfers charge directly to Al species and does 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:
- Sandia National Labs., Albuquerque, NM (United States); Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000; AC02-76CH00016
- OSTI ID:
- 10197026
- Report Number(s):
- SAND-94-2716C; CONF-941115-1; ON: DE95003355; BR: GB0103012; CNN: Grant DMR16616-A02
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society,Boston, MA (United States),28 Nov - 2 Dec 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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