Hi Chris,
One thing to keep in mind is that it is not wrong to eliminate part of
your signal; it just means you're losing a little bit of data. This is
similar to a common filtering mistake that beginners make when trying
to choose the maximum end of their fitting range: they look at the
paths they are including, and try to set Rmax high enough to include
most of the contribution from the paths they are including. What they
should be doing, however, is to look at the paths they are not
including, and set Rmax low enough so that the contributions from
those paths are tolerably small.
Looking at correlations between background parameters and fitted
parameters when the "fit background" option is selected also helps
provide you with information. I'll admit that the "fit background"
button confuses me a bit, though (I always have to spend ten minutes
convincing myself again as to what exactly it is doing), so someone
else should explain how that can be used to help address your question.
--Scott Calvin
Sarah Lawrence College
On Oct 23, 2009, at 3:51 PM, Chris Patridge wrote:
Hello everyone,
In removing background, most literature suggests Rbkg value of 1.0
because below this represents mostly noise and low freq components
not part of the scattering effect. In using Feff and viewing the
individual paths calculated a number of them have paths near 1.5 A,
therefore meaning that they have some contributions very close to
1.0 A and below in R space due to phase shift. Has anyone modeled
materials which contain these rather short Reff and how did you
decide what was scattering and noise?
Thank you all,
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