Title

Surface electronic structure and chemisorption on corundum transition-metal oxides: α-Fe2O3

Document Type

Article

Publication Date

1-1-1987

Abstract

Ultraviolet photoemission spectroscopy has been used to study the electronic structure of both nearly stoichiometric, well-ordered α-Fe2O3 surfaces and surfaces containing point defects. The interaction of O2, H2O, H2, and SO2 with both types of surfaces has also been investigated. The energy levels of the five 3d electrons on the Fe3+ ions overlap those of the filled O 2p orbitals, leading to a complex valence band about 10 eV wide. Oxygen-vacancy surface defects produced by Ar+-ion bombardment result in a conducting surface layer containing both Fe2+ and Fe0 ions. The well-ordered α-Fe2O3(0001) surface is relatively inert with respect to all four molecules studied, with exposures greater than 103 L (1 L10-6 Torr sec) necessary before any chemisorption could be seen. For large exposures, the O2-surface interaction gives rise to a negative adsorbed species. H2O adsorbs dissociatively on both well-ordered and defect surfaces, resulting in adsorbed OH- ions. SO2 appears to bond primarily to surface oxygen ions, yielding a complex similar to SO4 2-. © 1987 The American Physical Society.

Publication Source (Journal or Book title)

Physical Review B

First Page

3413

Last Page

3421

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