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A: Fachverband Atomphysik

A 16: Atomic Clusters II

A 16.1: Fachvortrag

Mittwoch, 4. März 2009, 14:00–14:30, VMP 6 HS-B

Ion and electron emission from Argon clusters in intense femtosecond XUV laser pulses — •Mathias Arbeiter and Thomas Fennel — Institute of Physics, University of Rostock, Germany

The ionization dynamics of Argon clusters in ultrashort and intense XUV laser pulses is investigated by molecular dynamics simulation. Corresponding experiments^[1] at FLASH free electron laser at λ=32 nm and λ=13 nm with intensities of I∼ 10¹²⁻¹⁴W/cm² have demonstrated the cluster response to be completely different to the behavior observed in the infrared and the VUV regime, where plasma heating processes dominate the laser-cluster coupling. In the XUV regime, in contrast to that, the measured photoemission spectra indicate a series of direct electron emission events in the developing cluster Coulomb field. According to this, nanoplasma formation takes place only if the cluster potential is sufficiently deep to suppress direct electron emission. In our MD analysis we focus on the impact of thermalization and laser heating on the electron and ion emission spectra. Whereas the low-energy tail of the photoemission spectra is severely affected by thermalization for higher intensities, laser heating through inverse Bremsstrahlung turns out to be insignificant^[2]. Methodical details and simulation results will be presented and discussed in comparison with experimental results.

[1] C. Bostedt et al., Phys. Rev. Lett. 100, 133401 (2008)

[2] M. Arbeiter, in preparation