The research group “Innovative fiber-optical sensing” investigates fundamental mechanisms of interaction between light and matter, i.e. absorption, scattering and luminescence. A special emphasis is placed on complex materials like hetero-phase systems (emulsions and suspensions) with structures in the nano- to micrometer regime. For that purpose innovative fiber-optical methods are developed allowing for a physical-chemical characterization of such demanding samples.
For example, Photon Density Wave (PDW) spectroscopy is used for the independent and absolute quantification of absorption and scattering properties of strongly light scattering materials and Diffuse Transmission experiments are employed to characterize the radiation transport through thin slabs of such materials. Aside from the determination of concentrations, particularly the size or even size distribution of the scattering particles or droplets and their interaction with each other can be assessed.
The methods mentioned above stand out in their ability to investigate extremely highly concentrated (>50 % v/v) hetero-phase systems without any dilution or sample preparation required. The experimental investigations are accompanied by simulations on the basis of Mie theory, different approaches for the treatment of dependent scattering and Monte-Carlo simulations. Apart from material characterization, the further development of PDW-spectroscopy by implementation of new instrumental and theoretical approaches is of special interest.