[Ifeffit] Ti data problem

[Carlo Segre]

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
segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org