Influence of structure in heterodyne electrophoretic light scattering.

Heterodyne light scattering is employed to probe the electrophoretic flow behavior of a concentrated, deionized model colloidal suspension. Both for the fluid and crystalline regime, the power spectra are well described as velocity distributions, which let assume that the power spectra are dominated by the self-dynamic structure factor. Furthermore, all measured power spectra show an increase of the frequency integrated intensity with the electric field. Since the number of particles should remain constant this finding is unexpected. These effects are rationalized on the basis of a new theoretical model including the influence of the structure factor and of the mobility polydispersity on the power spectra.