[Ifeffit] Hephaestus: Absorption Data Source

Matt Newville newville at cars.uchicago.edu
Mon Nov 13 13:13:34 CST 2017


On Mon, Nov 13, 2017 at 10:34 AM, Bruce Ravel <bravel at bnl.gov> wrote:

> On 11/13/2017 11:15 AM, Daniel Przyrembel wrote:
>
>> Still I can't see any reference to 'Keski-Rahkonen and Krause' in
>>
>
>
> http://bruceravel.github.io/demeter/documents/Athena/hephaes
> tus.html#absorption
>
>
> Here is the relevant bit from Feff:
>
> https://github.com/xraypy/feff85exafs/blob/master/src/COMMON/setgam.f
>
> Note that that bit in Feff is less sophisticated than you might think. My
> memory (Matt or John might remember better) is that Steve Zabinski (main
> author of Feff6) "interpolated" those values from the plots in the K&R
> paper.  This was done with a ruler back in the days before we had software
> tools for such chores.  I am not saying that the values in setgam.f are
> wrong -- just not as precise as you might imagine.
> <https://www.bnl.gov/ps/beamlines/beamline.php?r=6-BM>



Yes, I can verify that this was done.  And also, the 1979 data from Krause
and Oliver is probably preferred and should probably be used. For the K
edges, the 1979 values are typically a bit lower than the 1974
(Keski-Rahkonen and Krause) data.   Conveniently the 1979 data is
tabulated, not graphed.

I have put the 1974 values into the X-ray database within Larch (
http://xraypy.github.io/xraylarch/xray/index.html and
https://github.com/xraypy/xraylarch/tree/master/plugins/xray) which is also
in scikit-beam database (https://github.com/scikit-beam/XrayDB).  Adding
the Krause and Oliver values (and making those the default) would be
great.

Anyone up for scanning the PDF of Krause and Oliver and cleaning up the
data into machine readable values like a spreadsheet?  If so, I'd be happy
to add them to the database.

--Matt
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