[Ifeffit] Athena bug and a question

[Kelly, Shelly D.]

Hi Silvio,

There are a number of ways to reduced the big spike at low k.  Sometimes
just tweaking E0, kmin, kmax, and k-weight are enough. 

My favorite approach is to use the model as a theory in the background
subtraction procedure.  I talk about how to do that in this presentation
file that I posted on the XAFS.org page:  http://www.xafs.org/Tutorials.
The pdf file is called:   Basics_of_XAFS_analysis.pdf.  You will want to
follow  Example #1 Aligning data and theory.  

The screen shots are a bit outdated.  Some of the parameters in Athena
are now hidden under the "Show additional parameters" button.

Good luck,
Shelly

---------------------------
Shelly Kelly
Argonne National Laboratory
Bldg 203, RM E113
9700 S. Cass Ave
Argonne, IL 60439

Molecular Environmental Science Group
www.mesg.anl.gov
skelly at anl.gov
phone: 630-252-7376


> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov [mailto:ifeffit-
> bounces at millenia.cars.aps.anl.gov] On Behalf Of Silvio Levy
> Sent: Wednesday, October 18, 2006 12:01 PM
> To: Ravel, Bruce D.
> Cc: XAFS Analysis using Ifeffit
> Subject: [Ifeffit] Athena bug and a question
> 
> 
> Bruce - thanks a lot for your post.  I've encountered this bug a few
> times, but I thought it might be a problem with my machine; in any
> case I could never replicate the problem and file a bug report.
> 
> I have another question to the list - how do I get rid of a spike at
low
> k?
> See for instance http://www.msri.org/~levy/files/Cinnabar/cinnabar.prj
> 
> If you open this file with Athena and plot in k-space, there is a big
> spike at low k; I haven't worried about this too much, but now that
> I'm starting to show other people my work, I'd like to get rid of it.
> Presumably my background subtraction is at fault, but how to fix it?
> The spike also messes the normalization.
> 
> Thanks,
> 
> Silvio
> 
> 
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit