[Ifeffit] Residual EXAFS spectra

Bruce Ravel bravel at bnl.gov
Mon Aug 30 08:57:09 CDT 2010

On Monday 30 August 2010 09:27:09 am sumitk at barc.gov.in wrote:
> Hi all,
> I am doing an EXAFS spectra analysis of Eu(III) sorbed on mineral oxides.
> In  course of this, I came across a lierature article(Geochimica et
> cosmochimica Acta 64(16),2737,2000.) where a residual spectra (denoting a
> particular shell) was generated after subtracting four other different
> paths contribution from the EXAFS spectra(k3.chi(k)). This procedure was
> adopted to identify and isolate different paths/shells informations
> available in the EXAFS spectra. As the paper doesnot explain about the
> procedure, I am little confused whether the author has adopted just the
> linear subtraction methodology(i.e, sum of few selected paths minus the
> original spectra) in creating the residual spectra or some other
> mathematical approach. 

The caption to figure 5 in the article you cite says:

 "Residual EXAFS (produced by subtraction of U=Oax, U-Oeq, U-C, and
  U-U shells) ..."

Seems pretty clear to me that what they show is the Fourier transform of 

    data_chi(k) - sum_of_specified_paths(k)


> Any one having experience in this analysis will
> please repond to my problem.
> I would also like to know the best way to identify different shells
> contribution in the EXAFs spectra.
> Thanking in advance
> Sumit Kumar


 Bruce Ravel  ------------------------------------ bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
 Building 535A
 Upton NY, 11973

 My homepage:    http://xafs.org/BruceRavel
 EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

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