RE: [Ifeffit] multielectron transition
Jensen, Mark P.
mjensen at anl.gov
Wed Jul 13 15:24:10 CDT 2005
I am aware of two examples in the literature where EXAFS have been fit without and with consideration of multielectron excitation. Both Found a 0.01 - 0.02 A contraction in the first shell scattering pathlength when the multielectron effects were removed. The relevant papers are:
P. D'Angelo, H.-F. Nolting, and N. V. Pavel, Phys. Rev. A, 53 (1996) 798
J.A. Solera, J. Garcia, and M. G. Proietti, Phys. Rev. B, 51 (1995) 2678
In the second paper they show that the effect of multielectron excitations for the lanthanide-aquo ions is unimportant in the fitting of the EXAFS for lanthanides heavier than samarium, and that the multielectron excitations are not even visible by the time one reaches dysprosium.
------------------------------
Mark P. Jensen
Chemistry Division
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439-4831
USA
630-252-3670
630-252-7501 FAX
mjensen at anl.gov
> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov
> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf
> Of Barton, David G.
> Sent: Wednesday, July 13, 2005 9:30 AM
> To: 'XAFS Analysis using Ifeffit'
> Subject: RE: [Ifeffit] multielectron transition
>
> 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
> >
> > Environmental Research Division, Building 203, Room E-165
> > Argonne National Laboratory phone and voice mail:
> (1) 630 252
> > 5033
> > Argonne IL 60439, USA fax:
> (1) 630 252
> > 9793
> >
> > My homepage: http://feff.phys.washington.edu/~ravel
> > EXAFS software:
> > http://feff.phys.washington.edu/~ravel/software/exafs/
> >
> >
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>
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