Hannover 2010 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 20: Atomic Clusters III (with MO)
A 20.5: Vortrag
Donnerstag, 11. März 2010, 15:30–15:45, F 303
Steplike intensity threshold behavior in extreme ionization of laser-driven Xe clusters — •Thomas Fennel1, Tilo Döppner1, Jan-Philippe Müller1, Andreas Przystawik1, Sebastian Göde1, Josef Tiggesbäumker1, Karl-Heinz Meiwes-Broer1, Charles Varin2, Lora Ramunno2, and Thomas Brabec2 — 1Institute of Physics, University of Rostock, Germay — 2Department of Physics, University of Ottawa, Canada
Highly charged Xeq+ ion generation up to q=23 is observed in XeN embedded in helium nanodroplets and exposed to intense femtosecond laser pulses (λ=800 nm). Laser intensity resolved measurements show that the high-q ion generation starts sharply at an unexpectedly low threshold intensity of about 1014 W/cm2. Above threshold, the Xe ion charge spectrum saturates quickly and changes only weakly for higher laser intensities. Good agreement between these observations and a molecular dynamics analysis [1] allows us to identify the mechanisms responsible for the highly charged ion production and the surprising intensity threshold behavior of the ionization process [2]: (i) rapid inner ionization of Xe to high-q states through an EII-avalanche sparked by TI of Xe atoms which is supported by an early plasmon resonance of the He shell and (ii) suppression of charge recombination by resonant heating of the Xe cluster. We find that resonant heating of the Xe cluster is less important for strong inner ionization but is the key to conserving the charge state distribution produced by avalanching.
[1] T. Fennel et al., Phys. Rev. Lett. 99, 233401 (2007)
[2] T. Döppner et al., submitted (2009)