[Ifeffit] New Method for Normalization?

Barton, David (DG) DGBarton at dow.com
Thu Sep 29 15:48:59 CDT 2005

XANES Aficionados,

I know most users on this list are hard-core EXAFS analysts, but some of us use XANES analysis to decipher mixed phases or use it to get structural clues when data quality isn't sufficient for EXAFS analysis.  Anyway, I have a question for those interested in quantitative analysis of XANES or those that are willing to offer an opinion on methods to normalize raw spectra to get reliable, repeatable comparisons of near-edge features.

Has anyone considered using the methods of Penner-Hahn to normalize their data to get reliable intensities of near-edge features?  The reference to their method of normalization is below:

J. Synchrotron Rad. (2005). 12, 506-510    [doi:10.1107/S0909049504034193]
"A method for normalization of X-ray absorption spectra"
T.-C. Weng, G. S. Waldo and J. E. Penner-Hahn

It is my understanding the Ifeffit uses a linear function to remove the pre-edge and a quadratic for the post-edge and that the Athena's flatten is a subtraction of these functions.  This is an excellent method under most scenarios since the background is usually fairly smooth and can be well approximated by a quadratic equation.  Personally, I have had only a few rare cases where the quadratic function on the post-edge was not sufficient to reliably normalize the data and in those cases a third-order polynomial was sufficient.  Does anyone else have an opinion on using alternative normalization routines?

  David Barton
  The Dow Chemical Company 

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