[Ifeffit] Ifeffit Digest, Vol 104, Issue 22

Fri Oct 14 10:34:30 CDT 2011

Julian:
I agree with Anatoly. The amplitude of the EXAFS is quite large. I have seen
a similar effect in metal foils and NP samples when you forget to take the
log of the I0 and IT. This also forces the S02 factor to be artificially
high (like it is for your samples) when fitting in Artemis. Maybe try to
re-adjust the raw data file upon importing into Athena and then see if your
spectra (intensities, features and S02) line up better with those from the
literature (and from the very useful Lytle database on XAFS.org).
Hope that helps
Dave

On Fri, Oct 14, 2011 at 9:14 AM,
<ifeffit-request at millenia.cars.aps.anl.gov>wrote:

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>   1. Re: Gold Nanoparticle first shell fitting (Kaiser, Julian)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 14 Oct 2011 14:14:00 +0000
> From: "Kaiser, Julian" <julian.kaiser at helmholtz-berlin.de>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] Gold Nanoparticle first shell fitting
> Message-ID: <DE491AE4BEF1864DB8831D1BC0E7EA1A0E554D33 at didag2>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Dear Anatoly,
>
> thanks a lot for your reply!
> I don't see the problem yet. In the attached file
> ("different_Au_foils.prj), there are two different gold reference foils
> measured at two different synchrotrons. There is some difference but not
> realy much. Could you please describe the regions that are worse comparing
> my gold foil-file to yours, or if possible, attache the file with both foils
> or at least a screenshot of the plot?
>
> Best regards,
> Julian
>
>
>
> ________________________________
> Von: ifeffit-bounces at millenia.cars.aps.anl.gov [
> ifeffit-bounces at millenia.cars.aps.anl.gov]" im Auftrag von "Anatoly I
> Frenkel [afrenke2 at yu.edu]
> Gesendet: Dienstag, 11. Oktober 2011 20:29
> Bis: XAFS Analysis using Ifeffit
> Betreff: Re: [Ifeffit] Gold Nanoparticle first shell fitting
>
>
> Something is horribly wrong with the data here.
>
> I overplotted your reference Au foil against mine, and yours has distorted
> XANES and too high EXAFS intensity compared to my data. Your amplitude
> factor is 1.54 which also confirms that something was wrong in the
> experiment. Perhaps - a misalignment? The NP data also look strange...
>
> I would not focus on the NP analysis until you figure out why your foil
> data is so strange.
>
>
>
>
>
> ________________________________
> From: ifeffit-bounces at millenia.cars.aps.anl.gov [
> ifeffit-bounces at millenia.cars.aps.anl.gov] on behalf of Kaiser, Julian [
> julian.kaiser at helmholtz-berlin.de]
> Sent: Tuesday, October 11, 2011 1:06 PM
> To: ifeffit at millenia.cars.aps.anl.gov
> Subject: [Ifeffit] Gold Nanoparticle first shell fitting
>
> Dear Ifeffit Community,
>
> I'm trying to fit a gold nanoparticle in the size of about 2 nm that is
> immobilized by polymers. For my research it's enought to fit the first shell
> only, becaues all I would like to analyze is the atomic distance in the
> nanoparticle. After the (hopefully) correct background substraction in
> Athena (athena file attached), there is a shoulder at approx. 2.1 Angstr?m
> in the R-space.
> In Artemis, fitting this shoulder seems not to be possible, while the fit
> for the reference (gold foil) seems to be fine. (both artemis files are
> attached to the e-mail).
> If the k-range is decreased from 12.388 to a value between 9 an 10, the
> shoulder disappears and the fit works fine. But I think by this change I
> might modify the data too much.
> Would be really nice, if sombody has an idea how to deal with the problem,
> to get a hint how to solve this.
>
> Thanks a lot,
> Julian
>
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> Helmholtz-Zentrum Berlin f?r Materialien und Energie GmbH
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> Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren
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> Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv.
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> Sitz Berlin, AG Charlottenburg, 89 HRB 5583
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> End of Ifeffit Digest, Vol 104, Issue 22
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-- 
**********************************
David Sprouster
Postdoctoral Research Fellow
Department of Electronic Materials Engineering
Research School of Physics and Engineering
The Australian National University
Canberra ACT 0200
Australia
Currently at Hysitron Inc. Minneapolis, MN, USA
T: +61 2 612 50868
F: +61 2 612 50511
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