Hello Jan:
You can use the theory for the first shell to determine the best value for E0. We show an example of how to do that in a book chapter that I can send to you directly. Here is a screen shot of the accompanying figure.
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[cid:image002.png@01DAA5D7.C0F2A4D0]
Kind Regards,
Shelly
From: Ifeffit On Behalf Of Jan-Benedikt Weiss
Sent: Monday, May 13, 2024 9:09 PM
To: ifeffit@millenia.cars.aps.anl.gov
Subject: [Ifeffit] Choice of E0 in the presence of a huge pre-peak
Dear all, since I am new to XAFS analysis, I do not have a proper understanding of how to chose E0 the right way if taking the first maximum of the derivative of µ(E) is not an option. In my dataset (K-edge of a Cu(I) coordination polymer with
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Dear all,
since I am new to XAFS analysis, I do not have a proper understanding of
how to chose E0 the right way if taking the first maximum of the
derivative of µ(E) is not an option. In my dataset (K-edge of a Cu(I)
coordination polymer with linear coordination environment), a huge
pre-peak far up the edge is present. Larch automatically detects E0 to
be in front of that peak which leads to a complicated subtraction of the
background in the EXAFS analysis (the spline does not align with the
shape of the edge; see attached plot) and will probably lead to other
problems. I thought of two alternative option to determine E0 but I do
not know if they are adequate.
Option 1: Take the second maximum of the derivative of µ(E) which
appears after the pre-peak (see attached plot). I guess this value is
still flawed by the pre-peak and therefore not accurate.
Option 2: Fitting a baseline curve under the pre-peak and select E0 as
the maximum of the derivative of that curve. Since this value will
probably lay underneath the pre-peak, it will not be suitable as the E0
value used in the background subtraction in the EXAFS analysis.
So do you have any suggestion on how to handle this case?
Best wishes
Jan
