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
