Raj,
Some comments and suggestions.
On Tue, Mar 10, 2015 at 11:11 AM, Raj kumar
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.
What does "with and without corrected Copper EXAFS" mean?
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
By itself would not worry me too mcuh.
increase in uncertainty value of E0 than the actual value.
What actual value? You mean the uncertainty in E0 increases when you go from 1 to 3 shells? That increase in uncertainty could easily be due to a worse overall fit.
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 Fourier transform of the data depends only on the k-space data, and the weighting and windowing applied. It doesn't depend on the values of the fitting parameters -- those affect only the Fourier transform of the model.
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.
Not sure what you mean.... larger and shorter than what? I would recommend fitting one spectrum first -- I don't quite understand why you have 2 spectra with an obvious E0 shift between them, and no (unless I missed something) shared parameters. --Matt