Measurement of Diffusion Coefficient in General

Consider a time-dependent correlation function (G(0,0)g(r, t)) (first introduced by Van Hove, 1954)  

By applying the Wiener-Khintchine theorem (Wiener, 1930 Khintchine, 1934 see Chapter 15), the scattering can be transformed into the power spectrum just like the pair 5(q, t) and /(co)  

If the scatteres are spherical, the orientation autocorrelation function is simplified to 

We now have the scattering intensity expressed more simply as 

This equation can be further transformed into a Lorentzian equation  

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