Organic molecular crystals are systems whose properties lie between those of isolated molecules with well-defined energy levels and inorganic solids with a band structure. The weak intermolecular coupling leads to a splitting of the energy states. We investigate how this unique energetic structure affects strong-field phenomena such as harmonic generation and how strong fields can be used to control the optical properties of organic molecular crystals.

Ultrafast and intense lasere pulses modify materials and lead to permanent changes. We performe coherent diffractive imaging experiments that allow to image the temporal evolution of a laser induced plasma in gold foils. 

Spin-crossover (SCO)-complexes are bistable molecular complexes in two different spin configurations, high-spin (HS) and low-spin (LS), which can be switched by external stimuli. We examine how temperature and the surrounding influences the switching behaviour and timescales with time resolved femtosecond spectroscopy. 

The energy absorbed by a molecule can be transferred to neighbouring molecules. Several of these steps allows to transfer and guide energy on the nanoscale which finds application in organic solar cells. We aim to understand how the supramolecular assembly, the geometric dimension and the energetic structure influences the  energy transfer distances.