[Ifeffit] phase shift correction

Ravel, Bruce bravel at bnl.gov
Sun Dec 2 11:29:10 CST 2007


Hi Bindu,

> > Why the peak in the Fourier transform of the experimental 
> > spectrum is less than the actual one. 

> The EXAFS equation is:

>               N S02 F(K)
>     chi(k) = ----------- exp(-2k^2 sigma^2) sin(2kR + phi(k))
>                 2kR^2

> In the oscillatory term, there is a piece that is the phase shift
> associated with the scattering of the photoelectron.  When you do a
> Fourier transform, the peak of the sin wave is not at R, rather it is
> shifted by an amount that depends on the size of phi(k).

That should be, of course, "...the peak of the *Fourier transform* of
the sine wave..."


 Bruce Ravel  ----------------------------------- bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at Brookhaven National Laboratory
 Building 535A
 Upton NY, 11973

 My homepage:    http://cars9.uchicago.edu/~ravel
 EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

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