For an adequate description of complex chemical systems, one needs to identify and characterize the relevant elementary chemical steps. In the gas phase these critical steps are mostly radical reactions, which drive processes such as the combustion of hydrocarbons or the atmospheric degradation of pollutants. The rates of these reactions usually depend on the temperature, the pressure, and the nature of the surrounding gas in a complicated manner. Hence, experiments over wide temperature and pressure ranges, often combined with a detailed kinetic modeling, are necessary for the determination of reliable rate data. In our group we study such reactions experimentally using laser photolysis or shock tube techniques and employ statistical rate theory for data analysis.
Femtosecond spectroscopy allows a direct observation of the first physico-chemical processes in molecules/materials upon light irradiation and is of central importance for a proper description of those systems. The investigations of such processes require femtosecond laser systems with large tunability ranges, which are at hand nowadays. Here, we give a brief outlook of our current research involving thermalization processes of solvated electrons in polar and ionic liquids, ultrafast internal conversion that play a crucial role e. g. in many polyenic systems as well as time-domain spectroscopy of clusters and single-walled carbon nanotubes .