Incoherent dynamic light scattering by dilute dispersions of spherical particles: wavelength-dependent dynamics

Dynamic light scattering (DLS) was performed on dilute suspensions of colloidal particles, where the scattering intensity was minimised by ellipsometric optics as in ellipsometric light scattering. Measurements at minimum intensity settings are dominated by the incoherent scattering properties, i.e. the deviations from the average scattering properties. The observed relaxation dynamics does not vary with the scattering angle, but depends on the wavelength λ of the employed light. Therefore, the process has a λ-dependence beyond the dependence included in the scattering vector. Such incoherent ellipsometric DLS could be applied to determine the residence time of particles in volumes with an extension comparable to λ, and to obtain detailed information on the dynamics of complex systems which is usually hidden by the dominating diffusive process.