Porod function

Parameter Description Units Default value
scale Source intensity None 1
background Source background cm-1 0.001

The returned value is scaled to units of cm-1 sr-1, absolute scale.

This model fits the Porod function

\[I(q) = C/q^4\]

to the data directly without any need for linearisation (cf. Log I(q) vs Log q).

Here \(C = 2\pi (\Delta\rho)^2 S_v\) is the scale factor where \(S_v\) is the specific surface area (ie, surface area / volume) of the sample, and \(\Delta\rho\) is the contrast factor.

For 2D data: The 2D scattering intensity is calculated in the same way as 1D, where the q vector is defined as

\[q = \sqrt{q_x^2+q_y^2}\]

Fig. 100 1D plot corresponding to the default parameters of the model.


G Porod. Kolloid Zeit. 124 (1951) 83.

L A Feigin, D I Svergun, G W Taylor. Structure Analysis by Small-Angle X-ray and Neutron Scattering. Springer. (1987)