[Ifeffit] Ifeffit Digest, Vol 91, Issue 30

[Elsa E. Sileo]

Thanks Matt,

now I realize that I can directly change de Eo in the Athena window,
Elsa

At 14:00 30/09/2010, you wrote:
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>    1. Re: Ifeffit Digest, Vol 91, Issue 28 (Matt Newville)
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>----------------------------------------------------------------------
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>Message: 1
>Date: Thu, 30 Sep 2010 11:28:28 -0500
>From: Matt Newville <newville at cars.uchicago.edu>
>To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
>Subject: Re: [Ifeffit] Ifeffit Digest, Vol 91, Issue 28
>Message-ID:
>         <AANLkTinRMxoi2ANd=H=a+Bir5FRG0rruw_UPYy53sfCE at mail.gmail.com>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Hi Elsa,
>
>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.
>
>Why is important to have a theoretical spectra with deltaE0=0?
>
> > When I compare the experimental and theoretical spectrum I see a mismatch
> > between the position of the nodes at low wavenumbers.
>
>Yes, that is what E0 does.
>
> > Having done this, how I have to proceed to correct the experimental
> > data in order to obtain smalller delta E0 values?
>
>I think what you are trying to do (though I don't understand why) is
>to adjust E0 for the experimental data so that the fit to a particular
>theoretical standard gives deltaE0 close to zero.  If so, you want to
>adjust E0 in the background subtraction.  If you change E0 by 8eV
>there, you should end up with a deltaE0 in the fit that is close to
>zero.
>
>Hope that helps,
>
>--Matt
>
>
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>End of Ifeffit Digest, Vol 91, Issue 30
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Dra. Elsa E. Sileo
Solidos Inorganicos
INQUIMAE - Dto. Qca. Inorganica, Analitica y Qca. Fisica; FCEN, UBA
Int. Güiraldes 2160, Pabellón 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