Hi Dien,
On Mon, Apr 13, 2020 at 2:02 PM Dien.Li@srnl.doe.gov
Hi, all
I fitted my Cr EXAFS data, but E0 was -2.5. I calibrated the spectrum in energy space by +10 eV, the spectra in K and R space were identical before and after this calibration, in contract to my understanding that the k space oscillations and R magnitude should shift. Could you please provide any direction on how to get E0 to position values or negative E0 is acceptable? Thank you so much.
An E0 of -2.5 eV should not be a problem. Basically, E0 gets selected for an experimental spectrum in a pretty ad-hoc way (maximum of the 1st derivative). The Feff calculations also make an assumption about where the energy threshold should be. It's not unusual or a problem for these to differ by a few eV. We would start to get concerned if the difference needed to be as large as 10 eV. Now, sometimes that is reasonable, but it can also indicate that the ligand or bond length is way off. I don't know what you mean by "calibrated the spectrum in energy space by +10 eV" -- you mean you added the number 10 to all energy points? That won't make a difference. Hope that helps, --Matt