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Published on: October 7, 2013
Geometry of α-Cr2O3(0001) as a Function of H2O Partial Pressure
M H M Ahmed1, X Torrelles2, J P W Treacy1
1Corrosion and Protection Centre, School of Materials, The University of Manchester , Sackville Street, Manchester, M13 9PL, U.K.
Abstract:
Surface X-ray diffraction has been employed to elucidate the surface structure of α-Cr2O3(0001) as a function of water partial pressure at room temperature. In ultra high vacuum, following exposure to ∼2000 Langmuir of H2O, the surface is found to be terminated by a partially occupied double layer of chromium atoms. No evidence of adsorbed OH/H2O is found, which is likely due to either adsorption at minority sites, or X-ray induced desorption. At a water partial pressure of ∼30 mbar, a single OH/H2O species is found to be bound atop each surface Cr atom. This adsorption geometry does not agree with that predicted by ab initio calculations, which may be a result of some differences between the experimental conditions and those modeled.
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