[Ifeffit] Sulfur EXAFS k oscillations

[Carlo Segre]

Hi Beth:

I suggest that you not use kw=3 as that will make these background 
subtraction oscillations worse.

Another thing you can try is to cut down the high end of your spline range 
to 13, then 12.5 and see if that makes it behave a bit better.  I find 
that it helps a lot when the data is a bit noisy or there is a slightly 
wavy background.  I also look at the FT to see how the background spline 
is doing.

Carlo

On Mon, 9 Apr 2018, Miller, Elizabeth Christine wrote:

> Hi all,
>
> I am analyzing some sulfur K-edge EXAFS data taken at 4-3 at SSRL. When I use a k-weight of k^3 to plot, my oscillations at high k reach over 100, which doesn't make sense to me. I have looked over the data with Riti, and it seems that while the XANES are rather self-absorbed due to high concentrations of sulfur-containing salt, the data can be normalized, and the EXAFS should contain some information. I've included screenshots in the attachment of plots of all of the k-weights as well as my parameters. The mixtures are solutions of organics (acetonitrile, 1,1,2,2-Tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether) with bis(trifluoromethane)sulfonimide lithium salt. I am also not hitting any other edges, as sulfur is the highest Z element in the solution. Any thoughts would be greatly appreciated!
>
> Thank you,
> Beth
>
>
>
> Elizabeth C. Miller, Ph.D.
> Postdoctoral Scholar
> Stanford Synchrotron Radiation Lightsource
> SLAC National Accelerator Laboratory
>
> E-mail: ecmiller at slac.stanford.edu<mailto:ecmiller at slac.stanford.edu>
>
>

-- 
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