[Ifeffit] Increase in uncertainty of Eo and fitting mismatch

Raj kumar rajrk37 at gmail.com
Tue Mar 10 11:11:39 CDT 2015

Dear All,

Recently, I recorded Copper foil EXAFS as a reference in (Dispersive EXAFS)
transmission mode at Soleil, Paris. For understanding the data quality (of
my sample), i started fitting copper EXAFS through Artemis. After the DATA
extraction, i fitted copper in Artemis and found a shift in energy. For
this reason, i have modeled with and without corrected Copper EXAFS in
Artemis. Initially, i started with first shell and progressed to three
shell fit through step by step. During the course of fitting, some of the
following troubles have been faced. Please help me to rectify it.

For first shell fit: Everything goes well and converged to reasonable
physical values of copper foil. Whereas for* further increment in copper
shells* leads to *increase in Debye-waller factor for all three
shells* and *increase
in uncertainty value of E0 than the actual value*.

Moreover, i have noticed that the (increase of shells in the fit) *not only
changes the physical parameters and also modifies the Fourier transform*.
The inference are the following: A shift in first and third shell of Cu-Cu
are observed, respectively, *to larger and shorter distance than the
experimental spectrum* with diminished second shell amplitude.

Although Copper foil EXAFS is standard and well known sample, i am stuck
with fitting. Please help me to overcome these problems. For your
reference, project file of Copper file is attached with this email.

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