[Ifeffit] EXAFS fitting - noisy data
Hu, Yang (HIU)
yang.hu at kit.edu
Mon Aug 30 15:32:34 CDT 2021
Dear Ifeffit members,
I have some fundamental questions regarding noisy data, and I am wondering
how to tell whether the data quality worth doing Fourier
transformation/EXAFS fitting or not.
For example, the attached MnO chi(k) data becomes noisy from 7 Å-1 when it
was measured up to 12 Å-1. The deglitching (left: red -> blue) mitigated the
strong dips but the high-k end still has too much noise. I practiced the
FT and fitting the 1st and 2nd shells by using the lower part. But My
questions here are:
1) How noisy would be too noisy? Like the data between 8 and 10 Å-1 in
the attached file, can they still be included for the FT?
2) We can choose the high-k end based on the signal-to-noise ratio, but
to what extend? With data being noisy from even 5 or 6 Å-1, can they still
be used?
3) For fitting the 1st and 2nd shells, I still lack of clear
understanding how the high-k portion can influence. If I measure a set of
samples, and one of them has much noisy data so a shorter k-range is picked
up for background subtraction and FT. In this case, can I still consider the
change or evolution in the fitted parameters systematic?
Thank you in advance,
Best regards,
Yang
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