Exciton Energy Transfer in Compelx Systems
Energy transfer in, for example, photosynthetic systems can be followed using ultrafast spectroscopy. The research group works on developing methods to predict and interpret experimental spectra. We are particularly interested in the transfer through photosynthetich super complextes to understand the full mechanism from light absorption in antenna complexes to energy conversion in reaction centers.Novel Spectroscopic Methods
We develop methods to predict and suggest new spectroscopic methods that are sensitive to specific physical processes. For example, rexently action-detected ultrafast spectroscopies allow the controlled study of exciton annihilation processes or charge separation.
Protein Structure and Dynamics
The 2DIR spectrum is sensitive to the structure of proteins. For example, the turn in Elastin, alpha-helices, beta-sheets, and polyproline structures particularly the turn in Elastin like peptides. However, a whole class of intrincically disordered proteins (IDPs) are not well understood. We study the structure and dynamics of these proteins using 2DIR spectroscopy.
Perovskite Solar Cells
Since the first perovskite solar cell was described in 2009 the efficiency of these devices has essentially exploded recently surpassing the efficiency of organic solar cells. We study the fundamental properties of these facinating materials in particular the dynamics of the organic cations embedded in the perovskite structure. (Collaboration with the Bakulin group (Cambridge) and other groups in the field.)
Two-Dimensional Sum Frequency Generation
The 2DSFG signal is sensitive to the structure of surface bound molecules. For example the stucture of membrame bound proteins can be determined by this technique.
Spectral Oscillations
Oscillations observed in two-dimensional optical spectra have got a lot of attention as it was proposed to be a signature of quantum coherent transport and these phenomena were observed in biological molecules. Rec§ent models, however, demonstrate that the oscillations are rather dominated by localized vibrational coherences. (Collaborations with the Miller group (Toronto/Hamburg) and the Kleinekathöfer group (Jacobs, Bremen).)
Water
Water is an omnipresent substance playing a crucial role for life. In biological systems the properties of water are different from that of pure water. We study the structure and dynamics of water in confined environments and in the proximity of hydrophobic groups. (Collaborations with the Pshenichnikov (Groningen) and Skinner (Wisconsin) groups.)
Excitation induced effects
The excitation of a molecule can change the way that it behaves. For example excitation can induce a rearangement of the environment (denoted the Stokes shift) or excitation can lead to specific hydrogen bond breaking or molecular rearrangements as seen in molecular motors. We study the effect of both infrared and visible excitations. (Collaborations with Vöhringer (Bonn) and Pshenichnikov (Groningen).)