[Ifeffit] Ti data problem

[Siliang Chang]

Hi Carlo,

Thank you for the response. I will try what you mentioned here. The data is
taken at APS beamline 5BMD. May I ask what is the effect of longer counting
times?

Siliang

-----Original Message-----
From: Carlo Segre [mailto:segre at iit.edu] 
Sent: Monday, August 08, 2016 4:05 PM
To: Siliang Chang <schang37 at uic.edu>
Cc: ifeffit at millenia.cars.aps.anl.gov
Subject: Re: [Ifeffit] Ti data problem


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