The central aspect of our project is the photo-induced control of elementary processes in simple molecules and aggregates. Control of photo-induced molecular processes has attained considerable success in recent years. It became most exciting when self-learning feedback loop algorithms were employed where tailored laser pulses can be generated, which drive the induced processes at a maximum yield along desired paths . An important issue in this regard is the information coded in the optimized laser pulse shape which supplies insight about the underlying processes. Small alkali systems are suitable for this aim since they exhibit a number of bound states available for resonant transitions with weak fields which aids the theoretical description and hence the interpretation.
Small noble metal clusters exhibit fascinating physical and chemical properties. In particular their ability to act as catalytic reaction centers with size dependent activity for important chemical processes qualifies them as model systems for kinetic and spectroscopic investigations. Our experiment aims to reveal details of the hitherto unknown reaction mechanisms of these small metal clusters with adsorbed molecules. The focus of our work is on gas phase kinetic measurements as well as on the investigation of femtosecond reaction dynamics via gas phase NeNePo-spectroscopy and surface laser spectroscopy. The work is part of the Sonderforschungsbereich 450: Analysis and control of ultrafast photoinduced reactions.
Many phenomena in nature cannot be satisfactory explained by the indoor experiment always performed in controlled conditions. For example, thunderstorm lightings require around ten times lower electric field strengths then those simulated in the laboratory. LiDaR (Light Detecting and Ranging) allows to look at atmospheric processes in their natural environment. In our approach to LiDaR two main aspects can be distinguished. The first is an ongoing measurement activity using aerosol LiDaRs constructed in our group. The second are experiments with fs-LiDaRs, which use extremely short femtosecond laser pulses. Such short pulses induce the whole range of non-linear effects in air. The fs-LiDaR research is supported by the German Science Foundation DFG (SPP 1176 CAWSES) and joint German-French (DFG/CNRS) project "Teramobile" (DFG SA 325/5).