Re: [Ifeffit] Reported W L3-edge and L2-edge energy

[Mike Massey]

On a tangentially related topic, I find that phosphorus K-edge XAS energy 
calibration conventions are still in a bit of a "Wild West" state, with a wide 
variety of materials and values in use for energy calibration. As an extreme 
example, one or two frequently cited papers in my field from the 2000s don't 
even report the material or value used for energy calibration, and only show 
portions of the spectra on an energy axis with values relative to an unknown E0.

I too have picked my own material and value, and will be the first to 
acknowledge that I did so out of necessity and ease of comparison to other 
available data, rather than because I thought it was correct.

The issue of calibration conventions and values definitely seems to be one that 
merits continued discussion. It has been interesting to watch things evolve 
over time in the case of iron, for example (it's good to know that 7110.75 is a 
candidate calibration value...) I appreciate Matt's detailed thoughts, and the 
data that he's been working with. Thanks Matt!

Cheers,



Mike





> On May 6, 2020, at 3:32 PM, Matt Newville  wrote:
> 
> 
> Hi Simon,
> 
> This is definitely a timely discussion for me, as I've been spending part of 
> the quartine working on collating data and expanding datasets for an XAFS 
> spectral database.  I'm hoping to have something ready for public comment and 
> to start asking for contributions of data in a few weeks, but I'll be happy 
> to have more discussion about that sooner too. 
> 
> I generally believe that the monochromator I use at GSECARS is both 
> well-calibrated and reasonably accurate.  That is, with 2 angular encoders 
> with a resolution of >130,000 lines per degree and an air-bearing, I believe 
> the angular accuracy and repeatability are very good.  I believe there are 
> equally good moons in existence.   As Matthew Marcus pointed to the Kraft 
> paper (which used an older source but 4-bounce mono to improve resolution), 
> we find that Fe foil is definitely better defined as 7110.75 and Cu foil is 
> between 8980.0 and 8980.5 eV.  That is, we've measured multiple foils, found 
> their first derivatives, and refined the d-spacing and angular offset.  We do 
> this about once per run, and the offsets tend to be very consistent.   For 
> sure, there is some question about whether the Kraft numbers are perfect.   
> For sure, putting Fe foil at 7110.75 +/- 0.25 eV appears to be "most right" 
> to us.
> 
> I also believe that we should probably re-measure these metal foils (and 
> other compounds) with a single calibration set for both Si(111) and Si(311).  
> We will probably have time to do that this summer in the time between 
> "beamline staff can get back to the beamline" and "open for outside users".
> 
> What I can tell you now is:  I have some data on W metal, WO2, and WO3 
> measured all at the same time on our bending magnet line, with Si(111).  An 
> Athena project for this is attached (W.prj).   I cannot vouch for the 
> absolute calibration. 
> 
> I also attach a set of foils (V, Fe, Cu, Mo) measured with the same 
> calibration (and Si(111) on our ID line), after adjusting d-space and offset 
> to be close to the Kraft values (CalibratedFoils2013.prj). 
> 
> I also attach a set of foils (Fe, Cu, Au L3, Au L2, Au L1, Pb L3, Pb L2, Pb 
> L1 edges) measured in 2016 (again, using Si(111) on our ID line), also with 
> the same calibration values (FeCu_Au_Pb.prj).  I'm pretty certain these use 
> the same d-spacing as the 2013 Foils to at least 5 digits.   For 
> completeness, all of the raw data files are also under 
> https://github.com/XraySpectroscopy/XASDataLibrary/tree/master/data
> 
> In my experience, the Pb L3 edge value has the biggest variation in the 
> literature, with values ranging from 13035 to 13055 eV (possibly a typo 
> somewhere along the line).  Fortunately, the Kraft-based calibration splits 
> the difference and puts the value at 13040 eV.
> 
> For W in particular, I will look if I have measured this recently on our ID 
> line.  I can tell you that I use CdWO4 as a phosphor and use that to focus 
> our X-ray beam.   I use this trick all the time: any tail from the beam 
> penetrating the phosphor is shortest at the peak of the white-line and for 
> CdWO4 that is always between 10210 and 10215 eV.
> 
> I hope that helps.  I am interested in trying to get all these values as 
> accurately as possible, so any comments or suggestions would be most welcome.
> 
> --Matt
> 
> 
> 
> 
> 
> 
> 
> 
> 
>> On Tue, May 5, 2020 at 5:14 PM Bare, Simon R  
>> wrote:
>> 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.  
>> 
>>  
>> 
>> Wh

[Ifeffit] Reported W L3-edge and L2-edge energy

[Bare, Simon R]

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.b...@slac.stanford.edu
Ph: 650-926-2629

[co_access_logo_text]

___
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

Re: [Ifeffit] Ifeffit Digest, Vol 207, Issue 8

[Christopher Chantler]

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

--
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
chant...@unimelb.edu.au<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdAITgSrfUpfDAUV5oUH1LFYBcz08w8xvHMJoosZRdagfQM.&URL=mailto%3achantler%40unimelb.edu.au>
 
chant...@me.com<https://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.html<https://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.html<https://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-requ...@millenia.cars.aps.anl.gov 

Sent: Wednesday, 6 May 2020 8:14 AM
To: ifeffit@millenia.cars.aps.anl.gov 
Subject: Ifeffit Digest, Vol 207, Issue 8

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-requ...@millenia.cars.aps.anl.gov

You can reach the person managing the list at
ifeffit-ow...@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. Reported W L3-edge and L2-edge energy (Bare, Simon R)


--

Message: 1
Date: Tue, 5 May 2020 22:14:12 +
From: "Bare, Simon R" 
To: "ifeffit@millenia.cars.aps.anl.gov"

Subject: [Ifeffit] Reported W L3-edge and L2-edge energy
Message-ID:



Content-Type: text/plain; charset="us-ascii"

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.b...@slac.stanford.edu<mailto:simon.b...@slac.stanford.edu>
Ph: 650-926-2629

[co_access_logo_text]

-- next part --
An HTML attachment was scrubbed...
URL: 
<http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20200505/415c9fa6/attachment.html>
-- next part --
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 10619 bytes
Desc: image001.png
URL: 
<http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20200505/415c9fa6/attachment.png>

--

Subject: Digest Footer

___
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/list

Re: [Ifeffit] Reported W L3-edge and L2-edge energy

[Matthew Marcus]

This paper:
Kraft, S., Stümpel, J., Becker, P., & Kuetgens, U. (1996). High 
resolution x‐ray absorption spectroscopy with absolute energy 
calibration for the determination of absorption edge energies. Review of 
Scientific Instruments, 67(3), 681-687.


has precision measurements of a bunch of edges including the Pt L-edges. 
 It shows an L3 energy of  11562.76(2)eV.  It refers to an older 
tabulation as well.  If you look at various tables, you find energies 
that vary considerably.  For instance, the paper cited above has the Fe 
K-edge as 7110.75eV, while some tabulations have it at 7112.

mam

On 5/5/2020 3:14 PM, Bare, Simon R wrote:

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 L_3 edge (11215.0 eV) as a calibration, the W L_3 - 
and L_2 -edges are *10203.4 eV* and *11542.4 eV*, respectively.


When using the Pt L_3 edge (11564.0 eV) as a calibration, the W L_3 - 
and L_2 -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 L_3 and L_2 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.b...@slac.stanford.edu 

Ph: 650-926-2629

co_access_logo_text


___
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit


___
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit