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A: Fachverband Atomphysik

A 38: Atomic Clusters IV

A 38.3: Vortrag

Freitag, 6. März 2009, 14:30–14:45, VMP 6 HS-C

Local ignition and anisotropic nanoplasma growth in laser-driven composite clusters — •Alexey Mikaberidze, Ulf Saalmann, and Jan M. Rost — Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

Doping a helium nanodroplet with a tiny xenon cluster of a few atoms only, sparks complete ionization of the droplet at laser intensities below the ionization threshold of helium atoms. As a result, the intrinsically inert and transparent droplet turns into a fast and strong absorber of infrared light.

Microscopic calculations reveal a two-step mechanism to be responsible for the dramatic change: Avalanche-like ionization of the helium atoms on a femtosecond time scale, driven by field ionization due to the quickly charged xenon core is followed by resonant absorption enabled by an unusual cigar-shaped nanoplasma within the droplet [1]. In contrast to the well known resonant absorption during the Coulomb explosion of both homogeneous [2] and composite [3] clusters, the resonance here occurs on an electronic time scale. We have indications that similar effects can be found in composite clusters of other species.

[1] A. Mikaberidze, U. Saalmann, and J. M. Rost, submitted, 2008.

[2] U. Saalmann and J. M. Rost, Phys. Rev. Lett. 91, 223401 (2003).

[3] A. Mikaberidze, U. Saalmann, and J. M. Rost, Phys. Rev. A 77, 041201(R) (2008).