Hi Jia:
For the first one of the spectra, I chose the shoulder in the derivative
at 4974 instead of the large peak. I consider the lower energy peak to be
a pre-edge feature due to the 3d quadrupole transitions and I generally
don't choose that. If the analysis later tells me that I am wrong, I move
it accordingly.
In this case, the 4974 positoin withthe other parameters I mentioned gives
a very reasonable FT.
Carlo
On Mon, 8 Aug 2016, Qingying Jia wrote:
Hi Carlo,
In many transition metal oxide cases like this, what would be the more
proper E0, the position of the apex of the first derivative peak or the
second one that is usually higher than the first peak, or it really
depends? I have seen people using either. In this particular case, it seems
like using E0 of 4967 eV (the first derivative peak position) gives cleaner
and more reasonable FT-EXAFS.
Regards,
Jia
On Mon, Aug 8, 2016 at 5:05 PM, Carlo Segre <se...@iit.edu> wrote:
Hi Siliang:
The first thing is that you have misidentified the edge position. Itis
way too high in all the data sets.
Put it at the inflection point of the main rise in the absorption curve
and you will find that the problem is much reduced.
The second thing is that you have a very bad backgrund problem in your
data and, in my estimation your usable data range is no moe than k=2 to
k=8. In fact, my suggestion is that you truncate the data by setting the
spline range to end at 8. The FT range should probably be set at 2-8 or
even 2-7 (somewhere in that range and put a window sill of dk=2 to get rid
of some of the ringing.
Once you do those things the data will look much more reasonable.
These data could probably have used some longer counting times. Where did
you take the data?
Carlo
On Mon, 8 Aug 2016, Siliang Chang wrote:
Dear all,
I am new to XAFS data analysis. I?m currently working on the XAFS data of
atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and
Ti
K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid
solution. However, Ti data really confuses me (please see attached file).
With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this
is something I have never seen in the literature. I?m wondering if this is
normal? Does this mean I should set a larger Rbkg value, say, around 1.5?
I?ve tried to fit the abovementioned Ti data using several models:
anatase,
rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of
those), so far no success. I would really appreciate if you can comment on
my data processing, any suggestions are welcomed, as I?m new to this, I?m
not sure if I?m doing it the right way.
Thank you very much.
Best regards,
Siliang Chang
--
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
se...@iit.edu http://phys.iit.edu/~segre se...@debian.org
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--
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
se...@iit.edu http://phys.iit.edu/~segre se...@debian.org
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