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.
Juan, 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. --Scott Calvin Sarah Lawrence College