Dear Hedy, On Sun, 23 Nov 2003, H H wrote:

Since, I am new in doing XAFS fitting, I hope some one just direct me little bit. In order to my fitting, I always filter each individual shell and then fit the back scattering. When I do that I get a good result. However, after I fit each individual shell and get R and Sigma^2, then I try to combine the shells together. The resultant spectrum does not match the fit. Do I have to combine the shells together after I fit each one individually or it is possible to do each one by its own?

I'm not sure I understand what you're doing. Maybe you can be more specific? Some questions: - Why do you always filter each shell for fitting, as opposed to fitting in R-space? This seems much easier to me, and avoids many complications. Still, fitting isolated shells ought to work. - How are you adding together the spectra from the different shells after the fit? - In what way does the sum of shells not match the fit? --Matt