Light scattering probes of viscoelastic fluids and solids

In this article, we discuss recent advances in static and dynamic light scattering applied to soft materials. Special emphasis is given to light scattering methods that allow access to turbid and solid-like systems, such as colloidal suspensions, emulsions, glasses, or gels. Based on a combination of single- and multispeckle detection schemes, it is now possible to cover an extended range of relaxation times from a few nanoseconds to minutes or hours and length scales below 1 nm up to several microns. The corresponding elastic properties of viscoelastic fluids or solid materials range roughly from below 1 Pa. to several 100 kPa. Different applications are discussed such as light scattering from suspensions of highly charged colloidal particles, colloid and protein gels, as well as dense surfactant solutions.