Frankfurt 2006 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 70: Poster Ultrakurze Lichtimpulse

Q 70.6: Poster

Donnerstag, 16. März 2006, 16:30–18:30, Labsaal

Plasma dynamics after femtosecond laser induced breakdown on water surface — •Cristian Sarpe-Tudoran¹, Andreas Assion², Matthias Wollenhaupt¹, Marc Winter¹, and Thomas Baumert¹ — ¹Universität Kassel, Institut für Physik and CINSaT, Heinrich-Plett-Str. 40, D-34132 Kassel — ²Femtolasers Produktions GmbH, Vienna

Laser-induced breakdown (LIB) in water has attracted much attention in the last decade due to its applications in precise ablation of biological tissues and microanalytics. Even if it is generally accepted that the primary process in LIB is the generation of high density free electrons, the breakdown plasma dynamics in the early times of formation hasn’t been accurately resolved and plasma parameters like transient electron density and expansion velocity - important for an optimization of the breakdown event - haven’t been measured directly. By using a combination of transient imaging techniques together with spectrally resolved reflection spectroscopy we investigated the optical properties of the free electron plasma generated by 35fs laser pulses on the water surface. The analysis of the data in the framework of a multireflection model yields a 20ps delay before the plasma expands with an initial velocity of 5900m/s. The transient electron density and the electron-ion-recombination rate were also accurately obtained.