Dear Li Dangdang, On Wed, 11 Feb 2004, Li Dangdang wrote:

Hi, i wonder if there is anyone to tell me what is the advantage of using real and imaginary part of transform in data and fit, compared with magnitude plot.

Best, DD

The real and imaginary parts of the Fourier transform include both the magnitude and phase terms. For XAFS, the phase term is much more sensitive than the magnitude to the distance and atomic species of the scattering atom. In principle one could fit to the phase and magnitude terms instead of the real and imaginary terms. My experience was (many years ago now) that this was not quite as robust as using the real and imaginary terms, mostly because of the 2*pi ambiguity in the phase. --Matt