[Ifeffit] Fe oxide

[Juraj Majzlan]

Hello,

I am trying to fit an EXAFS spectrum of an X-ray amorphous
Fe precipitate. In a model (goethite), there are Fe atoms
at 3.02, 3.29, and 3.45 A. Fitting the two most distant
shells of iron gives strange results. Fitting them
simultaneously gives very high amplitudes (32, -66) which
cancel each other (fig. 1) and produce a beautiful and
unreasonable fit (fig. 2).

Fitting them separate gives small ('reasonable')
amplitudes, but the distance (dr) have very high
uncertainties, e.g., dr = 0.12 +- 20.3.

Can I expect to resolve these three Fe shells or is it
asking too much?

I am also attaching the Artemis file, but will appreciate
any comments and suggestions.

Juro Majzlan


----------------------------------
Juraj Majzlan
Institute of Mineralogy and Petrology
Albert-Ludwig-University of Freiburg
Albertstrasse 23b
Freiburg, D-79104, Germany
telephone +49-761-203-6416
fax +49-761-203-6407
http://www.minpet.uni-freiburg.de/sites/personen/majzlan.html
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