Hello,
It seems to me that you have some more problems than just ss values.
The data collection range seems a little short just ~300 eV past the
edge. Amp is quite high and delr is very large. I am an expert by no
means but I might suggest that you have the wrong model. The model is
trying to compensate for high R space magnitude by making amp above 1
and ss negative. Have you considered your data processing in Athena?
Did you use the default settings? I would guess Cu-O bonds might be
too short for the presets in Athena. How did you check your model?
Buena salud,
Chris Patridge
On Jul 14, 2010, at 2:59 AM, Abhijeet Gaur <abhijeetga...@gmail.com>
wrote:
Hi all,
I read the discussion on negative Debye waller factor. As
per the discussion the negative value of this factor shows that the
model has shortcomings, so it should be corrected.
I am also getting the same problem while fitting one of my
samples. It is a Cu complex whose EXAFS data is taken at Dispersive
EXAFS beamline at RRCAT, Indore, India.
In the complex the nearest neighbours of Copper atom are
Nitrogen and Oxygen.
I am getting a very good fit upto 3rd shell but the problem
is that all ss parameters are coming negative. I checked the model
it seem correct.
Also I am getting a peak below 1 Angs which is also getting
fitted but I am not able to get that whether it is a real or due to
some noise.
I am attaching herewith the results of data analysis and
fitting.
Thanks in advance
With regards
Abhijeet Gaur
Vikram University
Ujjain, INDIA
<Cu complex fitting results.doc>
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