[Ifeffit] k-weight in Artemis
SCalvin at slc.edu
Wed Sep 27 11:10:59 CDT 2006
At 11:42 AM 9/27/2006, Juan wrote:
>Scott, when I said "strange" spectra, I mean spectra very different (compared
>to k3) and with sharp valley between peaks.
I teach at Sarah Lawrence College, where we like to insist that our
students aren't strange, just different. :) In fact, that goes for
the faculty too...our recruiting slogan is (no kidding): "You're
different, so are we."
So the Fourier transform of a kwt 1 spectrum may look very different
from the Fourier transform of a kwt 3 spectrum. There's nothing wrong
or unusual about that. Remember: EXAFS Fourier transforms are not
radial distribution functions, although they do correlate to them.
You can't, for instance, equate the relative height of two peaks in
the Fourier transform to the relative coordination number at two
distances from the absorbing atom. On the other hand, if as a
function of some external variable (time, temperature,
concentration...) you see one peak go up while another goes down, you
might hypothesize that there are changes in the average coordination
number at two distances. But that hypothesis would have to be tested
by modeling (e.g. Artemis/Ifeffit) or comparison to known
standards--there are other phenomena that could be causing the change
in the peak heights.
Sarah Lawrence College
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