[Ifeffit] Shift in Eo when fitting PtO2 and similar samples

[Clément Laskar]

Dear Yanny Chen,

You can find recorded and fitted EXAFS and HR-EXAFS spectra of PtO2 in our
following paper:

Laskar, C., Bazarkina, E. F., Kokh, M. A., Hazemann, J. L., Foulon, S.,
Leynaud, O., ... & Pokrovski, G. S. (2022). Exploring Platinum Speciation
with X-ray Absorption Spectroscopy under High-Energy Resolution
Fluorescence Detection Mode. *Minerals*, *12*(12), 1602.


The spectra can be directly downloaded at the following link on the
sshade database:

https://www.sshade.eu/data/experiment/EXPERIMENT_GP_20181107_001

https://www.sshade.eu/data/experiment/EXPERIMENT_CL_20210211_001


Maybe it could help you to deal with your fitting problem to compare your
spectra and your fit with ours,


Regards,


Clément LASKAR


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Dear all,



I am looking at EXAFS of PtO2 powders and Pt particles supported on TiO2. I
used a beta-PtO2 crystal structure data for the PtO2 EXAFS and after the
first shell fit, I observed a large shift in Eo (delta Eo of ~14 eV) in my
fit parameters. When I tried to fit the Pt foil to obtain the So2, the
energy shift also seemed high (delta Eo of ~7 eV). I am wondering if there
could be a problem in the selection of Eo prior to EXAFS analysis? I left
the Eo as the energy at the first peak of first derivative (ifeffit
default).

All of the data were also aligned using the reference foil in Athena before
looking at EXAFS. I am wondering what would have caused this shift? Any
help is appreciated, thank you.



Best regards,

Yanny
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