[Ifeffit] Bkg removal problem

[Bruce Ravel]

Alfred,

I certainly encourage you to look at Shelly's book chapter. It's very
useful.

The question you ask is one that we hear frequently on this mailing
list.  I don't mean anything bad by saying that -- in fact, it's an
excellent question that every practitioner of XAS needs to come to
terms with early on in his or her XAS career.  Indeed, I am pleased
that you are insightful enough to recognize your confusion and wise
enough to ask for help.

That said, I am a bit weary of answering questions about Rbkg on the
mailing list.  Yours ain't the first! ;-)

Rather than answering here, I decided to write up a wiki page on the
topic.  That way, I'll have something to point to the next time
someone asks about Rbkg.

Here it is:
  http://xafs.org/TheoryAnalysis/BackgroundRemovalWithAutobk

Hope it helps,
B


On Friday 10 September 2010 10:25:50 am Shelly Kelly wrote:
> Hi Alfred:
> 
> You should take a look at my book chapter. I go through a lot of
> details on how to remove the background. If you want a copy just send
> me an email directly and I'll send you a pdf.
> 
> Cheers,
> Shelly
> exafs at netzero.com
> 
> On Fri, Sep 10, 2010 at 8:42 AM, Alfred Hummer
> 
> <alfred.hummer at univie.ac.at> wrote:
> > Hello,
> >
> > Currently I am working on a Ga XAS spectrum.
> > I'm trying to extract the EXAFS data but I'm not sure if the background
> > function is right, or how to set the right values.
> >
> > I played around with different setting for kmin and Rbkg.
> > So far I know that Rbkg defines the cutoff for the bkg frequencies in the
> > FT optimization and setting it to high leads to loss in information, as
> > more high frequencies are included in the bkg.
> >
> > I also read that it is advisable to exclude strong white lines from the
> > spline range (increasing kmin?). Would this a strategy in my case?
> >
> > I attached the project file.
> >
> > Maybe someone has a clue. The more I tried the bigger my uncertainty.
> >
> > best regards
> >
> > Alfred
> >
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> 
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> 

-- 

 Bruce Ravel  ------------------------------------ bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
 Building 535A
 Upton NY, 11973

 My homepage:    http://xafs.org/BruceRavel
 EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/