ABSTRACT
In EXAFS modeling, we are usually fitting either the Fourier transform or the back-transform. According to the Rayleigh criterion (Section 4.5.2 of Chapter 4), we can just barely resolve peaks in the Fourier transform with a spacing of
ΔR k k =
−( ) pi
2 max min (11.1)
If we fit over a range from Rmin to Rmax, that means we could consider there to be a number of independent points given by
N R R
R
k k R R ind =
−( ) =
−( ) −( )max min max min max min Δ
pi (11.2)
This is often known as the Nyquist criterion, due to its relationship to an analysis of the information content of telegraph signals by Harry Nyquist (Nyquist, 1928).
