Light Scattering-Traditional & Modern-In the Study of Colloidal Systems

The fundamentals of the traditional (intensity) light scattering method are reviewed together with the application to a variety of macromolecules of both corpuscular and asymmetric form. With the introduction of the laser, improvements in traditional light scattering became possible but more importantly, new possibilities arose which made use, particularly, of the coherence properties of laser radiation. Thus dynamic light scattering is concerned with the intensity fluctuations in time which arise from the various possible motions of the scattering particles. Special digital correlators have been introduced to measure the intensity correlation function as the delay time is varied. From such information and, particularly, with the further use of computer methods, it is now possible to measure diffusion coefficients for a wide variety of scattering particles (from enzymes tb viruses) and to investigate velocity distributions for motile micro-organisms. Many further possibilities remain to be explored.