Quantitative determination of the oxidation state of iron in biotite using x-ray photoelectron spectroscopy: I. Calibration
- Pennsylvania State Univ., University Park, PA (United States)
- Lehigh Univ., Bethlehem, PA (United States)
- Johns Hopkins Univ., Baltimore, MD (United States)
X-ray photoelectron spectroscopy (XPS) analyses of Fe(III)/{Sigma}Fe were calibrated with nine single crystals of biotite of known Fe(III)/{Sigma}Fe content. Peak shape parameters for the component Fe{sup 2+} and Fe{sup 3+} Fe 3p peaks were obtained by a constrained lease squares fitting method that minimized the difference between Fe(III)/{Sigma}Fe determined by XPS and wet chemistry/electron microprobe (WCEM) analyses. Fe{sup 2+} and Fe{sup 3+} peak separation was estimated from the separation of minima in the second derivative of Fe 3p spectra. The single set of derived peak parameters yielded a good linear correlation (r = 0.87) between XPS and WCEM values over the sample displaying progressive oxidation during XPS analysis resulted in Fe{sup 2} and Fe{sup 3+} component peak shapes largely consistent with the constrained least squares fitting methods. Beam damage, which appeared to be restricted to three single crystals with low {Sigma}Fe, low Fe/Mg, and high Fe(II)/{Sigma}Fe, caused increases in Fe(III)/{Sigma}Fe that were proportional to the duration of sample exposure. 60 refs., 6 figs., 7 tabs.
- DOE Contract Number:
- FG02-95ER14507
- OSTI ID:
- 586815
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 61, Issue 21; Other Information: PBD: Nov 1997
- Country of Publication:
- United States
- Language:
- English
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