[Ifeffit] Problem with large so2

[Raj kumar]

Dear All,


I have been trying to fit EXAFS signal of YbVO4 both in bulk and
nanoparticles form. Here, I would like to estimate so2 from bulk
(reference) and subsequently use the number, as normalization parameter, to
calculate the co-ordination number in all nanoparticles. Nanoparticles were
synthesized by solution route. From our earlier understanding on the
synthesis, in some cases, Yb may or may not completely involve in reaction.
Therefore, I except Yb in two environments, one surrounded by mere oxygen
(in precise oxygen-Hydrogen; due to disorder one may expect a single peak)
and another one in YbVO4 environment. With this info and for reasonable
fit, I have used two so2 as free parameters for N: one for first shell
(oxygen at two distances) and another for rest other shells.  If I use
single so2, I obtain the value of around 0.92 with unsatisfactory fit
whereas the fit seems plausible with two so2 i.e., 0.75 and 2.2,
respectively. Using the same strategy, I could successfully fit the
nanoparticles again with large second so2 (1.79). From literature and
IFEFFIT earlier discussion, i understood that so2 should be between 0.8-1.2
value. Here, I would like to know, does this huge second so2 value makes
sense? is the obtained so2 value can be used to calculated coordination
number for unknown? Further, i have attached my worked files with this
message.


Regards,

Raj
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