HI, Do you know what the Ramsauer-Townsend effect is, and how it manifests in XAFS (for heavier metals in particular)? Try simulating Pt foil, and process the simulated chi(k) with a large k range, and shorter ranges. See how k-range affects
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HI,

Do you know what the Ramsauer-Townsend effect is, and how it manifests in XAFS (for heavier metals 
in particular)?
Try simulating Pt foil, and process the simulated chi(k) with a large k range, and shorter
ranges. See how k-range affects resolution?
Look at F(k) in the feff0001.dat file.  See the structure?
(Sorry...been slow getting my new computer fully running, otherwise
I would do this for you to illustrate.)

In short, the foil, processed to kmax = 20 invAng looks fine.
e.g. like:
https://www.researchgate.net/figure/Structural-analysis-of-the-Pt-Mo-Ni-NWs-XANES-A-and-EXAFS-B-analysis-of-Pt-L-3-edge_fig2_319398432
or
https://www.youtube.com/watch?v=FMHQ2Wi0fVM

Bruce has a short lecture on speakerdeck on this for Au:
https://speakerdeck.com/bruceravel/the-ramsauer-townsend-effect-in-x-ray-absorption-spectroscopy

Hope this helps...

cheers,
-R.




On Sun, Nov 2, 2025 at 5:31 PM FAN Dongxiao via Ifeffit <ifeffit@millenia.cars.aps.anl.gov> wrote:
Dear All, My target is the L3-edge of Pt foil and Pt-contained high-entropy alloy. In the Pt foil L-edge FT-EXAFS (k range: 3-20 A-1), there is a strange peak lower than the first near neighboring peak. This low-r peak makes confused because
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Dear All,

 

My target is the L3-edge of Pt foil and Pt-contained high-entropy alloy.

In the Pt foil L-edge FT-EXAFS (k range: 3-20 A-1), there is a strange peak lower than the first near neighboring peak.

This low-r peak makes confused because I did not found in other metal foil spectra.

Also this peak cannot be reduced by increasing the Rbkg value.

When I decrease the k range, this strange peak disappears with phase shift.

 

In the Pt-contained high-entropy alloy, this strange peak becomes more pronounced than the 1st NN.

 

Can anyone can give me help interpret this strange peak?

 

Best regards,

Fan

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JASRI, Sping8

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