Interaction of H2S with α-Fe2O3(0001) surface

[摘要] The atomic-scale structural changes in an alpha-Fe2O3 (hematite) (0001) surface induced by sulfidation and subsequent oxidation processes were studied by X-ray photoemission spectroscopy, LEED, and X-ray standing wave (XSW) measurements. Annealing the alpha-Fe2O3(0001) with a H2S partial pressure of 1 x 10(-7) Torr produced iron sulfides on the surface as the sulfur atoms reacted with the substrate Fe ions. The oxidation state of the substrate Fe changed from 3+ to 2+ as a result of the sulfidation. The XSW measured distance of the sulfur atomic-layer from the unrelaxed substrate oxygen layer was 3.16 angstrom. The sulfide phase consisted of three surface domains identified by LEED. Formation of the two-dimensional FeS2 phase with structural parameters consistent with an outermost layer of (111) pyrite has been proposed. Atomic oxygen exposure oxidized the surface sulfide to a sulfate (SO42-) and regenerated the 4 alpha-Fe2O3(0001) substrate, which was indicated by a (I x 1) LEED pattern and the re-oxidization of Fe to 3+. (c) 2007 Elsevier B.V. All rights reserved.

[发布日期] 2007-11-01

[关键词] X-ray standing waves;surfaces;hematite;hydrogen sulfide;pyrite