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

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 207, Issue 8

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Today's Topics:

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


Message: 1
Date: Tue, 5 May 2020 22:14:12 +0000
From: "Bare, Simon R" <>
To: ""
Subject: [Ifeffit] Reported W L3-edge and L2-edge energy

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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
SLAC National Accelerator Lab
2575 Sand Hill Road
Menlo Park CA 94025<>
Ph: 650-926-2629


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