On Sat, Jan 30, 2016 at 7:35 PM, Ritimukta Sarangi <ritimukta@gmail.com> wrote:
Hello,
I was recently asked about the accuracy of this formulation for obtaining EXAFS resolution and I did not have a good answer. Can someone point to a reference or explain here?
Thank you for your time,
Best,
-Riti
The deltaR = pi / 2DeltaK follows from general Fourier analysis and formulas like it can be found in many signal processing textbooks. For on-line resources, googling "Frequency resolution Fourier transform" gives several good references.
The idea is that (using sound-waves as an example) in order to distinguish two close frequencies (say 440 Hz from 441 Hz, so a different of 1 Hz), you have to sample many periods (pi seconds) to be able to do this.
For EXAFS, if there are contributions from two neighbors that are very closely spaced, you would have to sample enough oscillations (go high enough in k) to see the effect of these two different distances beating against each other. If you don't go out far enough in k, you can't tell that these two contributions are actually from different distances.