RE: [Ifeffit] multielectron transition

[Barton, David (DG)]

Iztok,

This is good stuff.  Mulitelectron features definitely throw at least a
small wrench in a typical background substraction routines that only
substract smooth, broad features using splines.

My naïve questions are:
1) What chemical elements show a sizable contribution from a multielectron
feature that could skew spline based EXAFS data analysis routines?
2) Are there any examples in the literature where a spline-based EXAFS
analysis (i.e. bond lengths, coordination numbers with statistics) is
performed  on a more complex system than with and without the removal of
these multielectron features as a comparison.


Dave

> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov 
> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf 
> Of Iztok.Arcon at p-ng.si
> Sent: Wednesday, July 13, 2005 10:21 AM
> To: bravel at anl.gov; XAFS Analysis? using Ifeffit?
> Cc: QY ZML; XAFSA Analysis usingI Ifeffit
> Subject: Re: [Ifeffit] multielectron transition
> Importance: Low
> 
> 
> Dear Bruce
> 
> An example of treating  atomic absorption background 
> including large multielectron features in L edge spectra of 
> Ce is given in the attached paper. Full atomic absorption 
> background for nearby elements Cs and Xe can be seen in the 
> second attached paper. Some other useful references on this 
> topic are given below:
> 
> 
> J. A. Solera, J. Garcia, M. G. Proietti, Phys. Rev. B 1995, 
> 51, 2678–2686.
> 
> A. Kodre, I. Arčon, M. Hribar, M. Štuhec, F. Villain, W. 
> Drube, L. Troeger, Physica B 1995,208&209, 379–380.
> 
> J. Padežnik Gomilšek, I. Kozjek Škofic, N. Bukovec, A. Kodre, 
> Thin Solid Films 2004, 446, 117–123.
> 
> E. Fonda, D. Andreatta, P. E. Colavita, G. Vlaic, J. 
> Synchrotron Rad. 1999, 6, 34–42.
> 
> 
> also some our references for atomic absorption spectra of K 
> edge exafs:
> 
> A. Kodre, I. Arčon, J. Padežnik Gomilšek, R. Frahm 
> Multielectron excitations in x-ray absorption spectra of Rb 
> and Kr J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513
> 
> A. Kodre, I. Arčon, J. Padežnik Gomilšek, A. Mihelič
> Atomic absorption background in EXAFS spectra of Rb in 
> inter-alkaline alloys Physica Scripta. Vol, T115, (2005) 218-220
> 
> A. Kodre, R. Prešeren, I. Arčon, J. Padeznik Gomilšek, M. 
> Borowski, A study of transferability of atomic background on 
> EXAFS spectra of simple gaseous compounds of As, J. Synch. 
> Radiation 8 (2001) 282-284
> 
> R. Prešeren, A. Kodre, I. Arčon, M. Borowski,
> Atomic background and EXAFS of gaseous hydrides of Ge, As, 
> Se, and Br, J. Synch. Radiation 8 (2001) 279-281
> 
>  There are many other papers of different authors on the 
> multielectron photoexcitations (see references in above 
> papers). Additional information on multielectron 
> photoexcitations in exafs spectra of L and K edges of 
> different elements and some subtraction procedures can be 
> found also on the dedicated web site of our group:
> 
http://www.p-ng.si/~arcon/xas/mpe/mpe5.htm

best regards and congratulations for  well  supported  program packages for
exafs analysis.

Iztok Arcon


> On Tuesday 12 July 2005 11:18, QY ZML wrote:
>> I am analyzing EXAFS of some rare earth systems. It is known that 
>> there are ?multielectron transitions in these systems. So, I want to 
>> know how to subtract multielectron process contribution generally and 
>> if ATHENA has a feature to do this. ?Thank you very much.
>
> Athena does not currently have a feature for doing this.  Drat!
>
> I would be willing to implement something empirical for doing this.  I 
> would like to see a discussion here on the mailing list of the merits 
> of different
> approaches.  Since I have never given this very much thought, I am not
> with
> any strong opinions for how it should (or should not) be done.  But I can
> certainly consider implementing it.
>
> B
>
> --
>  Bruce Ravel  ----------------------------------- bravel at anl.gov  -or-
>                                                   
> ravel at phys.washington...edu
>
>  *** My cell phone number has changed.  Please ask if you need the new 
> number
>
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>  Argonne National Laboratory         phone and voice mail: (1) 630 252
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>
>  My homepage:    http://feff.phys.washington.edu/~ravel
>  EXAFS software: 
> http://feff.phys.washington.edu/~ravel/software/exafs/
>
>
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