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Shortcut to group's Thesis papers Currently Funded Projects: Interaction of laser pulses with finite systems of matter such as small clusters or molecules produces intermediate excited systems that release their energy through a rich variety of competing relaxation mechanisms. The interplay between the possible decay pathways dictates the final products of laser-matter interaction, such as unimolecular fragmentation, electron emission and radiative decay. These relaxation processes often involve many degrees of freedom of the cluster system, thus laser initiated dynamics can occur on multiple time scales and are therefore difficult to treat theoretically on equal grounds. For example, while direct photo-fragmentation may occur on the femtosecond time scale, long-time “thermionic emission like“ fragmentation dynamics on picosecond and even up to microsecond or millisecond time scales can surprisingly occur due to competing rapid internal conversion and thermalization of the energy provided by the laser. This research will explore the time resolved photofragmentation dynamics of small clusters, by using femtosecond pump-probe fragment imaging experiments on mass selected fast ion beams. Dependence of the chemical processes, such as internal conversion and thermalization, which are involved in laser–matter interaction, on cluster size and on laser intensity will be examined. First experiments will concentrate on basic systems of rare gas cations RGn+, in which the ion core chromophore will be excited with a pump laser and the dynamics leading to fragmentation of the core or evaporation of loosely bound rare gas atoms will be probed with a time delayed laser pulse probe. These measurements will provide first time resolved experimental insight into the competition between these different fragmentation pathways in such finite systems of matter.
- Extreme Dynamics |
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