Interpretation of Fe K XANES Pre-Edge Spectra of Hematite
Based on Cobalt Optical Spectra
SR Sutton1,2, MD Dyar 3, JS Delaney4,
M Newville1. GR Rossman5
1GeoSoilEnviroCARS, and
2 Department of
Geophysical Sciences, The University of Chicago, IL, U.S.A
3Department of Earth and Environment, Mount Holyoke College,
South Hadley, MA, U.S.A
4Department of Geological Sciences, Rutgers University,
Camden, NJ, U.S.A
5Division of Geological and Planetary Science, California
Institute of Technology, Pasadena, CA, U.S.A
Abstract
Microanalysis of Fe 3+/ΣFe is an
important goal in undestanding the redox histories of terrestrial and
extraterrestrial planetary materials. Our work explores the suitability
of the synchrotron micro x-ray absosprtion near-edge structure (XANES)
technique for this purpose. High-resolution XANES measurements have
been reported on powders and glasses,1,2 but proper interpretation of
pre-edge peak multiplicity remains problematic. In this study, we
tested the predictive capabilities of the “Z+1” model by comparing Fe
K-XANES pre-edge spectra of hematite (corundum structure) with Co
optical spectra of corundum. This approach would allow use of Co
optical spectra to predict the multiplicity, orientational effects, and
energy of valence electron levels in Fe XANES spectra of other
important minerals.