Kratky plot

A diagrammatic representation of scattering data on large particles, obtained at different angles but at the same concentration, constructed by plotting $( sin ⁡ θ 2 ) 2 Δ R θ$ vs. $( sin ⁡ θ 2 ) 2$ , or $q 2 Δ R θ$ vs. $q$ and used for the determination of molecular shape. $Δ R θ$ is the excess Rayleigh ratio, $P θ$ the particle scattering function, $θ$ the scattering angle and $q$ the length of the scattering vector.

Source:

Purple Book, p. 67