[Ifeffit] Normalization in Athena
Kropf, Arthur Jeremy
kropf at anl.gov
Mon Oct 26 09:27:28 CDT 2009
I agree that Athena applies its (her) algorithm correctly. Whether that
algorithm is correct may be a matter of opinion. The apparent
discrepency Lisa sees is due to Athena's algorithm:
i.e., fit preedge line, fit postedge function to normalization range,
extrapolate both functions to edge energy to find edge step.
Another option would be to fit predge line and subtract it. After that,
fit the post edge normalization range.
With Athena, if there is a non-zero slope to the preedge line and you
choose norm order 1, you get Lisa's result. With normalization order 2
or 3, the results should either be the same, or at least, much closer.
> -----Original Message-----
> From: ifeffit-bounces at millenia.cars.aps.anl.gov
> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf
> Of Kelly, Shelly
> Sent: Monday, October 26, 2009 9:08 AM
> To: XAFS Analysis using Ifeffit
> Subject: Re: [Ifeffit] Normalization in Athena
> Hi Lisa,
> Be sure that Athena has been rigorously tested and she does
> know how to normalize data. It is much more likely that the
> default values are not the "best" ones for your data.
> My book chapter goes over how Athena normalizes data in
> detail. If you send me your email address I'll send you a
> copy. In particular see figure 14-16.
> dr.sdkelly at gmail.com
> > -----Original Message-----
> > From: ifeffit-bounces at millenia.cars.aps.anl.gov [mailto:ifeffit-
> > bounces at millenia.cars.aps.anl.gov] On Behalf Of Gudrun Bovenkamp
> > Sent: Monday, October 26, 2009 8:42 AM
> > To: ifeffit at millenia.cars.aps.anl.gov
> > Subject: [Ifeffit] Normalization in Athena
> > Hey everybody,
> > while I try to figure what effect normalization has on Linear
> > combination fitting in my lead L3 edge XANES system, I came accross
> > this problem:
> > Athena does not normalize correctly:
> > Normalization in Athena (post-edge): using 1.order
> normalization, no
> > flattening (which in this case is irrelevant anyway),
> points +199 eV
> > and +200 eV above E0.
> > Normalization in Origin (post-edge): using point 13235 eV (+200 eV
> > above E0); dividing the spectrum column by that value.
> > See the two examples in the attachment.
> > In both examples the normalized spectrum imported from
> Athena does not
> > have the norm value of 1 at 13235 eV. Why is that? The
> offset is also
> > not the same for every spectrum. That undoes the normalization
> > routine.
> > Greetings,
> > Lisa
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
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