[Ifeffit] Ifeffit Digest, Vol 91, Issue 28

[Shelly Kelly]

Hi Elsa:

As Matt suggested, you want to change E0 in Athena to produce a new chi(k)
spectrum.  You can read the theoretical chi(k) spectrum that you made with
E0=0 into Athena, adjust E0 for the measurement, and then plot in k the data
and theory to see them match at low k.

I encourage you to poke around at the project files that I put at
www.xafs.org/ShellyKelly.  These project files show how to reproduce the
relevant figures in the book chapter.



Good luck,
Shelly

On Thu, Sep 30, 2010 at 10:33 AM, Elsa Sileo <e_sileo at yahoo.es> wrote:

> Dear Matt,
>
> I have to perform EXAFS analysis, and when I tried to fit the first shell,
> I found deltaE0 values of about 8 eV. Following the paper of Kelly et al
> (Analysis of soils and minerals using X-ray absorption spectroscopy. In
> Methods of soil analysis, Part 5: Mineralogical methods; 2008; pp 446)
> I fitted the first shell obtaining values for deltaE0, sigma^2; delta R
> and amplitude. Then, using the obtained values, and making deltaE0=0, I got
> the theoretical signal.
> When I compare the experimental and theoretical spectrum I see a mismatch
> between the position of the nodes at low wavenumbers.
> Having done this, how I have to proceed to correct the experimental data in
> order to obtain smalller delta E0 values?
>
> Thanks in advance,
>
> Elsa
>
> --- El *mié, 29/9/10, ifeffit-request at millenia.cars.aps.anl.gov <
> ifeffit-request at millenia.cars.aps.anl.gov>* escribió:
>
>
> De: ifeffit-request at millenia.cars.aps.anl.gov <
> ifeffit-request at millenia.cars.aps.anl.gov>
> Asunto: Ifeffit Digest, Vol 91, Issue 28
> Para: ifeffit at millenia.cars.aps.anl.gov
> Fecha: miércoles, 29 de septiembre, 2010 14:00
>
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>    1. Re: Aligning Energy scales (Matt Newville)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 28 Sep 2010 12:55:15 -0500
> From: Matt Newville <newville at cars.uchicago.edu<http://es.mc278.mail.yahoo.com/mc/compose?to=newville@cars.uchicago.edu>
> >
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov<http://es.mc278.mail.yahoo.com/mc/compose?to=ifeffit@millenia.cars.aps.anl.gov>
> >
> Subject: Re: [Ifeffit] Aligning Energy scales
> Message-ID:
>     <AANLkTima_bGt5OO=K-Vb-0aRGwb9AC_W6BcBLwgCAg4t at mail.gmail.com<http://es.mc278.mail.yahoo.com/mc/compose?to=K-Vb-0aRGwb9AC_W6BcBLwgCAg4t@mail.gmail.com>
> >
> Content-Type: text/plain; charset=ISO-8859-1
>
> Dear Elsa,
>
> It sounds like you want to adjust the data chi(k) so that deltaE0 is 0
> in a fit.  Is that correct, or are you trying to do something else
> (say, align the XANES)?    If that assumption is correct, you want to
> change the E0 used to extract chi(k) from the experimental spectra --
> the E0 of the background subtraction.  That is what sets k for the
> data.
>
> If that's not clear or not the right question, let us know,
>
> --Matt
>
> On Mon, Sep 27, 2010 at 2:00 PM, Elsa E. Sileo <sileo at qi.fcen.uba.ar<http://es.mc278.mail.yahoo.com/mc/compose?to=sileo@qi.fcen.uba.ar>>
> wrote:
> > I need to align a measured spectra to a theoretically calculated spectra.
> > I fitted the first shell obtaining values for deltaE0, sigma^2; delta R
> and
> > amplitude.
> > Then, using the obtained values, and making deltaE0=0, I got the
> theoretical
> > signal.
> > But I do not know how to use this last theoretical fit to align the
> spectra.
> > Can somebody help me?
> >
> > Thanks,
> >
> > Elsa
> >
> >
> > Dra. Elsa E. Sileo
> > Solidos Inorganicos
> > INQUIMAE - Dto. Qca. Inorganica, Analitica y Qca. Fisica; FCEN, UBA
> > Int. G?iraldes 2160, Pabell?n 2, Piso 3, Ciudad Universitaria - C1428EHA
> > CABA - Argentina
> > Tel: (54 11) 4576 3380 ext. 113
> > Fax: (54 11) 4576 3341
> > e-mail: sileo at qi.fcen.uba.ar<http://es.mc278.mail.yahoo.com/mc/compose?to=sileo@qi.fcen.uba.ar>
> >
> >
> >
> >
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