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