https://doi.org/10.1351/goldbook.K03416

A diagrammatic representation of scattering data on large particles, obtained at different angles but at the same concentration, constructed by plotting (sin θ2)2.ΔR(θ) vs. (sin θ2)2, or q 2 Δ R θ vs. q and used for the determination of molecular shape. ΔRθ 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, 1^{st} ed., p. 67 (http://old.iupac.org/publications/books/author/metanomski.html)

Purple Book, 1