[Ifeffit] Ifeffit Digest, Vol 204, Issue 1

[Christopher Chantler]

Dear Christian and all
I think we  do not know yet, as the limits are getting better with improved techniques and error analysis, but it is a really good question.

One can discuss limits from transmission versus fluorescence, in mM, in ppm; and separately perhaps in mass or mL or microL; or in e.g. atoms or molecules. I think every beamline has some guidelines, for their implementation. So yes it depends a lot on atomic number, density, need for a particular k range (e.g. XANES, normal XAFS, XERT etc.), beamline flux, and experimental method.

Some of these estimates will be in the forthcoming International Tables for Crystallography, and earlier estimates are in earlier treatises.

Best wishes, Chris

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Christopher Chantler, Professor, FAIP, Fellow American Physical Society
Editor-in-Chief, Radiation Physics and Chemistry
Chair, International IUCr Commission on XAFS; CIT, CCN
IPP, International Radiation Physics Society
School of Physics, University of Melbourne
Parkville Victoria 3010 Australia
+61-3-83445437 FAX +61-3-93474783
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Subject: Ifeffit Digest, Vol 204, Issue 1

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Today's Topics:

   1. XAFS detection limit (Christian Wittee Lopes)


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Message: 1
Date: Thu, 6 Feb 2020 23:39:13 -0300
From: Christian Wittee Lopes <chriswittee at gmail.com>
To: Ifeffit at millenia.cars.aps.anl.gov
Subject: [Ifeffit] XAFS detection limit
Message-ID:
        <CAJHLRaEz1SJ8dsA+WySAq4Uc2JR=cHApDQ+yZ+yHguqELU+tOw at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Dear all,

Recently I was questioned about the EXAFS detection limit when describing
different metal species in a bimetallic sample.

By checking Pd and Cu K-edges, for example, I found Pd metal nanoparticles
and CuO clusters, respectively. But additional techniques tell me I can
have copper atoms in intimate contact with the Pd nanoparticles. What would
be the minimum amount of these "single atoms" needed to be detected by
EXAFS? is there a detection limit or it depends on several parameters?

Thanks!!!

--
*Christian Wittee Lopes*

*Postdoctoral Researcher*
Institute of Physics, Universidade Federal do Rio Grande do Sul (UFRGS)
Phone: +55 54 992430264
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