Research Interests of S. Wiegand

 

The precise knowledge of transport coefficients as diffusion and viscosity in mixtures and solutions plays an important role in chemical processes. The experimental determination of these quantities is often more difficult than the determination of static properties since the system has to be moved into a non-equilibrium state. The sensitive holographic Thermal Diffusion Forced Rayleigh Scattering method is advantageous when studying the thermal diffusion process in binary mixtures close to the critical point and in ordinary mixtures, polymer solutions and colloidal dispersions. It only requires a relatively small displacement from equilibrium compared to other methods.

Conventional light-scattering is a powerful tool to study aggregation of macromolecules in solutions. Unfortunately, the experiments are limited to diluted samples due to the presence of multiple scattering in turbid samples. It has been shown that the 3D cross correlation technique is a useful tool to suppress multiple scattering in highly turbid solutions. A modified one-beam-cross correlation modification should be implemented into a conventional light-scattering set-up for routine measurements.