[Ifeffit] lifetime broadening of pre-edge peaks?
Joshua Kas
joshua.j.kas at gmail.com
Mon Oct 10 14:02:09 CDT 2011
Hi Matthew,
This may be a minor (and possibly different) point, but vibrational
broadening can be different for different pre-edge peaks. See for example,
Keith Gilmore and Eric L Shirley 2010 *J. Phys.: Condens. Matter* *22*315901.
Cheers,
Josh Kas
On Mon, Oct 10, 2011 at 11:42 AM, <ifeffit-request at millenia.cars.aps.anl.gov
> wrote:
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> Today's Topics:
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> 1. Re: number of independent points (George Sterbinsky)
> 2. Re: lifetime broadening of pre-edge peaks? (Matthew Marcus)
> 3. Re: lifetime broadening of pre-edge peaks? (Anatoly I Frenkel)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 10 Oct 2011 14:04:07 -0400
> From: George Sterbinsky <GeorgeSterbinsky at u.northwestern.edu>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] number of independent points
> Message-ID:
> <CALoY8YwBz3jLWTLX+dosjiXs6Fv3RpG_UfG2yEz-X3XVn17abg at mail.gmail.com
> >
> Content-Type: text/plain; charset="iso-8859-1"
>
> Bruce, Matt, and Jeremy,
>
> Thank you for explaining this. Your responses are much appreciated.
>
> George
>
> On Mon, Oct 10, 2011 at 11:35 AM, Bruce Ravel <bravel at bnl.gov> wrote:
>
> > On Monday, October 10, 2011 10:35:12 am George Sterbinsky wrote:
> > > Since I haven't received a response to my previous question, I just
> > wanted
> > > to make sure I asked it clearly.
> >
> > I suspect the lack of response had more to do with it being a
> > non-trivial question asked on a Friday afternoon :)
> >
> > > To elaborate, I am attaching a log from
> > > Athena. The log file lists:
> > >
> > > "Independent points = 27.057617188"
> > >
> > > If I attempt to reproduce this result using the equation in the feffit
> > > document, I find
> > >
> > > Nidp = { [2*(kmax - kmin)*(Rmax-Rmin) / pi] + 2} = { [2*(14 - 0.5)*(4.2
> -
> > > 1.0) / pi] + 2} = 29.50197417,
> > >
> > > where I have used the k-range and R-range in the log file as kmax,
> kmin,
> > > Rmax, and Rmin.
> > >
> > > Can someone explain to me why may calculation does not reproduce the
> > number
> > > given for "independent points" in the log fie?
> >
> > George,
> >
> > A quick examination of the ifeffit source code shows that there are
> > two issues:
> >
> > 1. Regardless of what it may say in the document, Ifeffit uses "+0"
> > rather than "+2". See line 345 of
> > http://cars9.uchicago.edu/svn/ifeffit/trunk/src/lib/iff_feffit.f
> >
> > A bit of history: Ed Stern wrote this paper back in 1993:
> > http://dx.doi.org/10.1103/PhysRevB.48.9825
> >
> > Over the years, many have expressed scepticism of his conclusion.
> > The Bayesian work I mentioned earlier suggests quibbling over the
> > value of N in the "+N" term misses the bigger issue. Ifeffit's
> > use of "+0" provides a conservative yet easily stated estimate of
> > Nidp.
> >
> > 2. The difference to the left of the decimal point has to do with the
> > fact that Artemis allows you to pick any value for kmin, kmax,
> > rmin, and rmax. When Ifeffit evaluates Nidp (and anything else)
> > is actually takes the nearest grid points to those four values.
> > The grid in k-space is 0.05 inv. Angstroms. This sets the grid in
> > R space to be about 0.03 Angstroms, but not exactly. So the
> > values of Rmax and Rmin used by Ifeffit to compute Nidp (and other
> > things) are not quite what you specified.
> >
> > At some point, George, you may want to bite the bullet and look at
> > source code. Details are not unknowable, they just might not be
> > written down anywhere beside the source code.
> >
> > Here is the top of Ifeffit:
> > http://cars9.uchicago.edu/svn/ifeffit/trunk/
> >
> > B
> >
> >
> > --
> >
> > 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/ifeffit/Demeter
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >
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> ------------------------------
>
> Message: 2
> Date: Mon, 10 Oct 2011 11:23:07 -0700
> From: "Matthew Marcus" <mamarcus at lbl.gov>
> To: "XAFS Analysis using Ifeffit" <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks?
> Message-ID: <6BBC1B5DFDEE4BE1902489451655B16B at als.lbl.gov>
> Content-Type: text/plain; charset="iso-8859-2"
>
> Thanks. While none of these have to do with pre-edge peaks such as are
> found in transition-metal oxides, the assumption of constancy of core-hole
> broadening does seem to work.
> mam
> ----- Original Message -----
> From: Iztok Ar?on
> To: XAFS Analysis using Ifeffit
> Sent: Monday, October 10, 2011 12:32 AM
> Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks?
>
>
> Dear Matthew
>
> you can find examples of determination of life-time broadening,
> deconvolution of XANES specra, and discussion about limitations due to noise
> in several papers, for example:
>
> A. Filipponi, J. Phys. B 33, 2835 (2000)
>
> A. Kodre, I. Ar?on, J. Padeznik Gomil?ek, R. Frahm
> J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513
>
> A. Kodre, J. Pade?nik Gomil?ek, A. Miheli?, I. Arcon
> Radiation Physics and Chemistry 75 (2006) 188-194
>
> J. Padeznik Gomilsek, I. Arcon, S. de Panfilis, A. Kodre,
> Phys. Rev. A 79, (2009) 032514,
>
> regards
> Iztok
>
> Matthew Marcus wrote:
> Is the core-hole lifetime broadening of pre-edge XANES peaks the same as
> at the main edge? I'm looking into issues of de-noising of XANES epsctra,
> so
> need to figure out how narrow real features can be.
> mam
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>
>
>
>
>
> --
> prof. dr. Iztok Arcon
> University of Nova Gorica
> Vipavska 13, POB 301
> 5001 Nova Gorica, Slovenia
>
> tel: +386 5 331 5227
> fax: +386 5 331 5240
> e-mail: iztok.arcon at ung.si
> http://www.ung.si/~arcon
> http://www.ung.si/~arcon/xas
>
>
> ------------------------------------------------------------------------------
>
>
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> ------------------------------
>
> Message: 3
> Date: Mon, 10 Oct 2011 18:42:07 +0000
> From: Anatoly I Frenkel <afrenke2 at yu.edu>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks?
> Message-ID:
> <545F89325F51764C902D37B42C9F4D539B55E9 at YUWEXCPM11.yuad.uds.yu.edu>
> Content-Type: text/plain; charset="iso-8859-2"
>
> I think experimental answer could be the simplest one. Perhaps there is
> anyone on the list who measured low concentrations of low Z absorber in the
> high Z host at both edges?
>
> For example, Cu in Ag (if does dissolve in Ag if made by rapid quenching)
> at Cu K-edge, and Ag K-edge (or just bulk Ag since the data will be the
> same). These should be solid solutions, of course.
>
>
>
> Then, despite the difference in phase shift, the EXAFS oscillations should
> be comparable in magnitude if the broadening is not significant, and it
> should be more intense for the Cu K-edge if the broadening at Ag K edge is
> significant.
>
>
>
> Another option: to hear from people doing HERFD. That is normally done on
> XANES, for the reason, I assume, that they do not see any advantage in
> EXAFS region, where broadening does not change compared to total
> fluorescence.
>
>
>
> I think the explanation that EXAFS should not be too sensitive to the life
> time broadening is that EXAFS originates from the final state interference,
> while the XANES - from both the final state interference and DOS. But may be
> experiments are showing the opposite, and that will prove me wrong.
>
>
>
> Anatoly
>
> ________________________________
> From: ifeffit-bounces at millenia.cars.aps.anl.gov [
> ifeffit-bounces at millenia.cars.aps.anl.gov] on behalf of Matthew Marcus [
> mamarcus at lbl.gov]
> Sent: Monday, October 10, 2011 2:23 PM
> To: XAFS Analysis using Ifeffit
> Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks?
>
> Thanks. While none of these have to do with pre-edge peaks such as are
> found in transition-metal oxides, the assumption of constancy of core-hole
> broadening does seem to work.
> mam
> ----- Original Message -----
> From: Iztok Ar?on<mailto:iztok.arcon at ung.si>
> To: XAFS Analysis using Ifeffit<mailto:ifeffit at millenia.cars.aps.anl.gov>
> Sent: Monday, October 10, 2011 12:32 AM
> Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks?
>
> Dear Matthew
>
> you can find examples of determination of life-time broadening,
> deconvolution of XANES specra, and discussion about limitations due to noise
> in several papers, for example:
>
> A. Filipponi, J. Phys. B 33, 2835 (2000)
>
> A. Kodre, I. Ar?on, J. Padeznik Gomil?ek, R. Frahm
> J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513
>
> A. Kodre, J. Pade?nik Gomil?ek, A. Miheli?, I. Arcon
> Radiation Physics and Chemistry 75 (2006) 188-194
>
> J. Padeznik Gomilsek, I. Arcon, S. de Panfilis, A. Kodre,
> Phys. Rev. A 79, (2009) 032514,
>
> regards
> Iztok
>
> Matthew Marcus wrote:
> Is the core-hole lifetime broadening of pre-edge XANES peaks the same as at
> the main edge? I'm looking into issues of de-noising of XANES epsctra, so
> need to figure out how narrow real features can be.
> mam
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov<mailto:Ifeffit at millenia.cars.aps.anl.gov
> >
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>
>
>
>
> --
> prof. dr. Iztok Arcon
> University of Nova Gorica
> Vipavska 13, POB 301
> 5001 Nova Gorica, Slovenia
>
> tel: +386 5 331 5227
> fax: +386 5 331 5240
> e-mail: iztok.arcon at ung.si<mailto:iztok.arcon at ung.si>
> http://www.ung.si/~arcon
> http://www.ung.si/~arcon/xas
>
> ________________________________
>
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
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