How does nature create complex morphologies and patterns out of simple building blocks? Structure formation in soft condensed matter on the micro- and nanoscale is controlled by intermolecular forces. On these lengths scales, interfaces may dominate the overall behavior. The newly established research group studies instabilities of complex liquids in various geometries and applies novel experimental techniques to understand the dynamics of biological systems such as vesicles and cells at or near interfaces.
The group is engaged in experimental studies of liquid crystals and similar materials at interfaces. Main topics are wetting, anchoring, and other interface-induced phenomena, defects in smectic films, and the use of liquid-crystal structures for new self-organizing soft matter systems.
This group aims to understand the solidification of complex fluids including soils and colloids. How do they freeze, or dry? How do they crack, change, order, or fail? Much of the work is inspired by simple geophysical patterns, such as mud cracks. We seek to understand how such patterns form, and what they imply about their host environment.
A growing number of experimental techniques relies heavily on short-pulse lasers. Our laser facility delivers pico- as well as femtosecond pulses mainly used for experiments that take advantage of non-linear optical processes (e.g., multiphoton laser-scanning microscopy, Coherent Anti-Stokes Raman Scattering microscopy).
Granular matter is not only a daily companion, it can also serve as a powerful model system for the physics far from thermal equilibrium. This is the realm of most interesting phenomena, from pattern formation and self-organization up to the complex processes of living matter.
Does a system of swimmers have to consist of living biological entities to move around and form swarms? Recent research in active particles and emulsions shows this is not the case. We aim to study hydrodynamics between droplets as well as collective interactions in a model system comprised of active liquid crystal droplets.
Today we can manipulate matter down to the atomic scale and this ability allows us to control and explore the rich and still vastly unknown features of systems away from equilibrium. In this group we employ computer simulations to understand the behavior of complex liquids and nonequilibrium systems. Our main goal is to identify the driving mechanisms of matter organization.
Granular media like sand, sugar or snow can exhibit physical properties similar to those of ordinary solids, liquids and sometimes even glasses. However, due to their dissipative interactions and their geometrical constraints a new type of statistical mechanics is needed to describe them.
We deal with the Statistical Physics of Non-Equilibrium Processes and Nonlinear Dynamics. Recent work focuses on far-from-equilibrium phase transitions like the fluidization transition of wet granular matter, the turbulence transition, and the formation of precipitation.
Overarching research projects
Using droplet-based microfluidics we investigate the dynamics of micro- and nanostructures in two-phase fluids, from the organisation of amphiphilic molecules at interfaces to droplet stability, motion and actuation in microchannels.
Wetting of complex surface geometries can be observed in a variety of biological systems as well as in industrial processes and applications. The most prominent example are the water repelling leaf of the Lotus plant. The pore space of sand stone filled with a mixture of mineral oil and water can be viewed as wetting of a random surface geometry, too.
On a liquid water micro-jet in vacuum the chemistry of aqueous solutions is studied by photoelectron spectroscopy with soft x-ray synchrotron radiation from BESSY. In cooperation with several theoretical and experimental groups, current studies include surface activity and alignment of molecular anions, electronic levels of solvated individual ions of transition metals, and of DNA in liquid water solution.