Re: [Ifeffit] Ifeffit Digest, Vol 204, Issue 1

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 -------------------------------------------------------------------------------------- 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 chantler@unimelb.edu.auhttps://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=mailto%3achantler%40unimelb.edu.au chantler@me.comhttps://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=mailto%3achantler%40me.com http://optics.ph.unimelb.edu.au/~chantler/xrayopt/xrayopt.htmlhttps://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=http%3a%2f%2foptics.ph.unimelb.edu.au%2f%7echantler%2fxrayopt%2fxrayopt.html http://optics.ph.unimelb.edu.au/~chantler/home.htmlhttps://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=http%3a%2f%2foptics.ph.unimelb.edu.au%2f%7echantler%2fhome.html ________________________________ From: Ifeffit on behalf of ifeffit-request@millenia.cars.aps.anl.gov Sent: Saturday, 8 February 2020 5:00 AM To: ifeffit@millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 204, Issue 1 Send Ifeffit mailing list submissions to ifeffit@millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email, send a message with subject or body 'help' to ifeffit-request@millenia.cars.aps.anl.gov You can reach the person managing the list at ifeffit-owner@millenia.cars.aps.anl.gov When replying, please edit your Subject line so it is more specific than "Re: Contents of Ifeffit digest..." Today's Topics: 1. XAFS detection limit (Christian Wittee Lopes) ---------------------------------------------------------------------- Message: 1 Date: Thu, 6 Feb 2020 23:39:13 -0300 From: Christian Wittee Lopes To: Ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] XAFS detection limit Message-ID: 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