Dynamic light scattering by non-ergodic media

The basic notions of dynamic light scattering (DLS) on non-ergodic media are presented and discussed. We present the results, obtained by DLS, for the intermediate scattering function of polystyrene latex particles that are dispersed in aqueous polyacrylamide gels. It is shown that these systems display non-ergodic features, implying that the time-averaged intensity correlation function (ICF) is not equal to the ensemble-averaged ICF.