Heidelberg 1999 – scientific programme

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SYCF: Symposium Cluster und Fullerene

SYCF 5: Cluster und große Moleküle (Poster)

SYCF 5.1: Poster

Tuesday, March 16, 1999, 16:00–19:00, PA

Femtosecond Spectroscopy of Small Alkali Clusters in Molecular Beams — •Porfirio Rosendo, Andreas Bartelt, Bernd Baptist, Cosmin Lupulescu, Stefan Vajda, and Ludger Wöste — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin

The ultrafast pump and probe experimental technique in the femtosecond time regime is a powerful tool to study the dynamics of excited states. The clusters are electronically excited with the first ultrafast laser pulse (pump pulse) into an excited state. The temporal evolution of the excited state is monitored with a second ultrafast laser pulse (probe pulse), which ionizes the excited particles after a well-defined variable time delay Δ t. The evolution of the transient ion signal reflects the dynamics of the excited state. Provided oscillations take place, the vibrational dynamics in the excited state can be monitored as well if the ionization probability from the excited state depends on the reaction coordinate. In the case fragmentation occurs, the lifetimes of involved excited states can be measured, too.
We employed the pump&probe technique to study the excited state dymanics in homogeneous and heterogeneous alkali trimer clusters. Fragmentation kinetics and vibrational dynamics of excited trimers will be discussed here, and first preliminary results obtained with chirped pump pulses will be shown.