Rayleigh-Gans-Debye and Mie theories in the determination of spherical particle sizes

The results of a light scattering study of four rubber latex samples using a dissymmetry technique are reported. Particle diameters found from the Rayleigh-Gans-Debye and Mie theories were in the range 1,400 to 2,000 A. In water the relative refractive index of these particles was m = 1.15 so that for particles of this size, the two accepted theoretical limitations for the RGD theory were exceeded. However, the results indicate that this theory can still be used to give particle sizes to within 5% for values of m approaching 1.15 and for diameters of up to 2,000 A.