Hi Guven, This is not unusual, in my experience, particularly if the chi(k) fit is not particularly good. XANES and EXAFS are sensitive to different aspects of the local environment. In particular, the chi(k) is much more affected by structure beyond the nearest-neighbors. In your system, it is unlikely that you "really" have a mixture of bulk ZnO and bulk ZnTiO3. For nearest neighbors, those two standards may be good enough, and may give you a decent fit to XANES that has some physical meaning. But for chi(k) those standards may not be sufficient, and, while the fit is doing what it can, the fractions may not be particularly physically meaningful. One piece of evidence that this is going on is if the chi(k) fit is "poor," that is, if the fitted chi(k) does not correspond well to the data. --Scott Calvin Sarah Lawrence College On Apr 6, 2009, at 5:31 PM, Guvenc Akgul wrote:
Dear all,
I have done Ti doped ZnO EXAFS data analysis but I guess it is getting mixture structure at high concentration for example 55% Ti doped ZnO.Also I done linear combination fit , but at fitting space norm(E),ZnO weight is 0.779 and ZnTiO3 is 0.221 then I changed fitting space is chi(k) ZnO weight is getting 25.2 and ZnTiO3 is getting 74.8 and it is not same like at fitting space norm(E) why?