Hi Brandon,
before someone gives you correct answer, could you shortly inform us, what is the E0 for reference foil, for each experimental data. As I understand you have a shift of 7eV between samples, but measured on samples, thus would be nice to see what is the shift for reference.
The second question comes for me automatically - have you done something with the beamline set-up between experiments ?
kicaj

W dniu 11-06-06 08:56, Brandon Reese pisze:

Hi all,

I am looking at EXAFS of thin film metal oxides. I am varying both metal content and the oxygen content of the films. I aligned the scans with a metal reference foil collected simultaneously. In Artemis, I have noticed that when changing between films with no extra oxygen versus those with extra oxygen there is a shift in the fitted E0 of ~1.5 eV (after aligning to the foil). I tried setting the E0 in Athena to the peak of the 1st derivative and the peak of the white line with the same result (~7 eV difference). I was a little surprised by the offset because in Athena the E0 values varied by <0.5 eV. I am not sure if the argument could be made that this shift is a result in a changing oxidation state because it doesn't show up in the XANES (at least qualitatively). Are there other experimental effects that could cause a shift like this, or is this likely something real in my material? If anyone want to see a representative group of data, let me know.

I also have an unrelated quick (I think) question on the EXAFS equation. In some references I see a term 1/(k R)^2 and in others it is 1/(k R^2). I couldn't really see any reason for the difference, unless it is to correct for subtle differences in how the other terms are defined.

Thanks
Brandon
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