Hi Abdul: You have significant self absorption effects. YOu can see this by loading both transmission and fluorescence data and comparing them. The trick I use when I have more than one shell close to each other is to constrain the sigma squared values to be equal for both paths. This will give you an average between the two. The real question is what is the sigma squared when you just use a single path? Carlo On Tue, 29 May 2018, Abdul Ahad wrote:

Hi all,

Thanks to Professor Pierre, Prof. Segre and Prof. Scott, for make some beautiful comments.

One thing i wish to mention here that i have both Fluorescence and Transmission data, with the same model transmission data give Amplitude around 0.72 but Fluorescence gives 0.15, Is this self absorption problem, as prof. Segre suggested. Also i have tried with one shell with N=6 and then 4 and 2 and i got the genuine trend on average under limit of error. But the for N=2 the sigma goes to 0.0001 order while for N=4 it is usual 0.001 order (this both have simultaneously taken in a one fit). Also N=6 gives all variable fine.

thanks

-- Carlo U. Segre -- Duchossois Leadership Professor of Physics Interim Chair, Department of Chemistry Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org