Static Light Scattering From Small Particles

Static light scattering from objects that are small compared to the wavelength of the light contains only a limited amount of information, due to the limited q range that is accessible. As for small-angle X-ray scattering (SAXS) and small-angle neutron (SANS) data, one can still use the Rayleigh–Debye–Gans theory. It is possible to bring the experimental results onto the absolute scale by using a secondary standard such as toluene. One can essentially determine three parameters of the scatterers from a Zimm plot: the molecular mass, M; the radius of gyration, Rg; and the second virial coefficient, A2. To determine the molecular mass, M, one needs to determine the refractive index increment of the sample at the wavelength used for the scattering experiment. Time-resolved experiments immediately show the tendency to aggregation in a system composed of small particles, as the scattering at low q values is directly proportional to the mean aggregation number.