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A: Atomphysik
A 7: Cluster
A 7.2: Vortrag
Dienstag, 23. März 2004, 11:15–11:30, HS 132
Electron Emission from Metal Clusters after Excitation with Intense Laser Fields — •Paul Radcliffe, Tilo Döppner, Josef Tiggesbäumker, and Karl-Heinz Meiwes-Broer — Fachbereich Physik, Universität Platz 3, Universität Rostock, 18051 Rostock
Neutral clusters of metal atoms (CuN, AgN, and PbN, N ∼ 1–1000) are exposed to intense, femtosecond laser pulses. From previous experiments, we find that the ionization dynamics of the Coulomb explosion show a strong time dependence [1,2]. Initially, the rising edge of the laser pulse ejects electrons via barrier supression. The cluster expands, in turn the plasmon energy sinks, and after several hundred femtoseconds it reaches the laser energy and enhanced ionization follows.
Since the collective electron response is probed, measuring the electron emission allows a direct study of the plasmon dynamics. In a first attempt we measured the total electron emission. The yield in all cases is found to be unexpectedly asymmetric, when pulses of different widths are used for excitation. The total sum exhibits a resonance when the pulse duration is about 1 ps.
[1] L. Köller et al., Phys. Rev. Lett. 82 (19), 3783-86 (1999).
[2] T. Döppner et al., Eur. Phys. J. D. 24, 157-160 (2003).