Thanks Bruce, I agree that the Se-O bond lengths are short but in SeO2, and Na2SeO3 as Se4+ "standards" there are Se-O bond lengths average around 1.7A. For example when I run feff on the SeO2 cif file it gives 1 Se-O bond at 1.623A and 2 at 1.793A, averaging at roughly 1.7A. I'm confident that the XANES I have for this sample show that the Se is pretty much all present as Se4+ and I think the first shell is very likely to consist of oxygens. I also tried another shell from the same feff as included in the data I sent, using O1_1 instead of O2_1 and the fit including Delr still points to an average Se-O bond length of about 1.7A with an Enot of around 10. I will try fitting with feffs based on different cif files with some different Se-O bond lengths, but if you have any other suggestions I'd be grateful. Thanks very much for your advice - it's appreciated. Regards Paul. -- Dr. Paul Bingham Postdoctoral Research Associate Immobilisation Science Laboratory Dept. of Engineering Materials University of Sheffield Mappin Street Sheffield S1 3JD UK Email: p.a.bingham@sheffield.ac.uk Direct Line: (0114) 2225473