Hi all, I am having some troubles when I fit XANES spectra with a library of standards. The unknown spectrum has been processed (background removal, normalization,...). If I understand correctly the documentation, I have two ways to fit the unknown spectra: - using "fit this group" and I will get the best fit using my standards library - using "fit all combinations" and I will get all the different fit results from the best to the worst. However, it appears that the result given by "fit this group" does not correspond to the best fit given by "fit all combinations" (it often corresponds to a higher R factor fit), and thus "fit this group" does not give me the best fit possible. Are these two fitting processes using a different fitting algorithm? I attached one example to this email. I am using a library of 8 different Fe standards to fit the unknown spectra. Thanks for your attention -- Adrien Couet Graduate Student Dept of Nuclear Engineering, Penn State University +1 814 865 9709 axc1019@psu.edu