[Ifeffit] Ifeffit Digest, Vol 207, Issue 8

Tue May 5 17:40:09 CDT 2020

Dear Simon, good work

Currently most synchrotron beamlines will report calibrations of the edge according to the inflection point, or first peak in the derivative spectrum. As we know, this changes with experimental resolution, monochromation pre-edge structure and bandwidth, so is neither a fixed definition nor fully portable. However, apart from direct [powder or single crystal] diffraction measurement post monochromation, this is one of the best markers we have to date.

The discrepancy you mention is quite large prima facie to be just the above, so more likely is a calibration error or even monochromation calibration error [of one or the other].

These studies are very important to make progress in the field and to cross-calibrate, and to question theoretical predictions based around the edge structure, which are ongoing.

[PS I did not directly answer your question!]

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
chantler at unimelb.edu.au<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=mailto%3achantler%40unimelb.edu.au> chantler at me.com<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=mailto%3achantler%40me.com>
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From: Ifeffit <ifeffit-bounces at millenia.cars.aps.anl.gov> on behalf of ifeffit-request at millenia.cars.aps.anl.gov <ifeffit-request at millenia.cars.aps.anl.gov>
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Subject: Ifeffit Digest, Vol 207, Issue 8

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Today's Topics:

   1. Reported W L3-edge and L2-edge energy (Bare, Simon R)

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Message: 1
Date: Tue, 5 May 2020 22:14:12 +0000
From: "Bare, Simon R" <srbare at slac.stanford.edu>
To: "ifeffit at millenia.cars.aps.anl.gov"
        <ifeffit at millenia.cars.aps.anl.gov>
Subject: [Ifeffit] Reported W L3-edge and L2-edge energy
Message-ID:
        <MWHPR07MB38690FD1A9915311AC5859A491A70 at MWHPR07MB3869.namprd07.prod.outlook.com>

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All:

We are wondering if others agree that the reported values for the W L3 and W L2 edges are incorrect. We recently noticed the following:

The "Edge" - defined by the inflection point of the absorption edge step

When using the Ir L3 edge (11215.0 eV) as a calibration, the W L3- and L2-edges are 10203.4 eV and 11542.4 eV, respectively.

When using the Pt L3 edge (11564.0 eV) as a calibration, the W L3- and L2-edges are 10203.3 eV and 11542.4 eV, respectively.

These observations are thus different than the reported values of 10207.0 eV and 11544.0 eV for the L3 and L2 edges, respectively.

Thanks in advance for the discussion and feedback.

Simon R Bare
Distinguished Scientist
SSRL, MS69
SLAC National Accelerator Lab
2575 Sand Hill Road
Menlo Park CA 94025

simon.bare at slac.stanford.edu<mailto:simon.bare at slac.stanford.edu>
Ph: 650-926-2629

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