Basic definitions in SAXS

The fundamental relation between the scattering intensity, I (s), and the corresponding nanostructure is given by Eq. (1) 

FVom this equation, it is obvious that r is a displacement of (the nanostructure) /(r) with respect to itself. Moreover, in Eq. (1), ( ) stands for the 3D 

Fourier transformation and the scattering power (or invariant) Q is defined 

Finally, the n-dimensional Fourier transformation of a function /(r) is defined 

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