[Ifeffit] Vanadium pre edge peak contributes to K-space?

Chris Patridge patridge at buffalo.edu
Tue Aug 25 10:44:38 CDT 2009

Bruce Ravel wrote:
> On Tuesday 25 August 2009 11:02:26 am Chris Patridge wrote:
>> Hello all,
>> After calibration, alignment and merging V K edge data, there seems to
>> be a large peak in R space below 1 A.  From most examples and readings,
>> this would seem to be noise since atoms do not reside that close to each
>> other.  Adding a background addresses this noise but then the number of
>> variables becomes too large and meaningless to the first shell R space
>> range.  I believe the problem lies with the large pre edge feature seen
>> with high valence state Vanadium compounds.  Any suggestions on how to
>> work through this and make realistic EXAFS analysis on these compounds.
>> Thanks everyone,
> Didn't Richard Mayes answer this same question from you last month?
>    http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-July/004365.html
> In my experience, Richard's answer was spot on for V K edge data.
> If Richard's good advice didn't help, then you need to be more
> explicit about what the problem is, perhaps by posting a small athena
> project file that demonstrates the problem.
> B
Yes it is a very similar question.  I did make this type of correction 
by setting E0 myself.  When moving to R space the data shows significant 
intensity below 1 A which I thought was noise but it may not be.  Are 
these low A signals data or noise is my main concern because EXAFS 
fitting does not fit all that well which then would point me to my model 
as the problem which I think i understand.

Thank you all for your patience,

Christopher J. Patridge
Graduate Student
SUNY Buffalo - Dept of Chemistry
716-645-6800 x 2110

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