Berlin 2005 – wissenschaftliches Programm

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A: Atomphysik

A 16: Atomic Clusters and Cold Atoms II

A 16.5: Fachvortrag

Mittwoch, 9. März 2005, 11:15–11:30, HU 3075

Semiclassical calculations of dual-pulse excitation of simple metal clusters — •Thomas Fennel and Josef Tiggesbäumker Karl-Heinz Meiwes-Broer — Universität Rostock, Universitätsplatz 3, 18051 Rostock

Motivated by recent measurements the time-dependent response of silver clusters have been explored theoretically within the dual-pulse excitation scheme for optical wavelengths (λ=800nm) [1]. Based on semiclassical time-dependent density-functional theory a microscopic simulation of the cluster dynamics is used to investigate the laser cluster interaction [2]. In accordance with the experimental results a strong dependence on the pulse delay is found for the ionization efficiency of the cluster. The major mechanism behind this effect is the known plasmon enhanced ionization, which remains efficient even for laser photon energies far below the the collective resonance of the cluster groundstate. The delay-dependence of the coupling of the second pulse to the cluster as well as patterns within electron spectra are are extracted form the calculations, for linearly and circular polarized pulses respectively. Key features, such as timescales for resonant coupling and maximum kinetic energies of the emittesd electrons are estimated in dependence of the laser intensity.

[1] T. Döppner, Th. Fennel, Th. Diederich, J. Tiggesbäumker and K.-H. Meiwes-Broer, submitted to Phys. Rev. Lett., 2004

[2] T. Fennel, G.F. Bertsch, and K.-H. Meiwes-Broer, Eur. Phys. J. D 29, 367 (2004)