https://doi.org/10.1140/epjd/e2002-00115-2
Resonant coupling of small size-controlled lead clusters with an intense laser field
1
Laboratoire de Spectrométrie Ionique et Moléculaire,
CNRS et Université Lyon I, 43 boulevard du 11 novembre 1918,
69622 Villeurbanne Cedex, France
2
DSM/SPAM/DRECAM, CEA Saclay, bâtiment 524, 91191 Gif-sur-Yvette Cedex, France
3
DRFMC/SI2A, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble, France
Corresponding author: a lebeault@lasim.univ-lyon1.fr
Received:
18
March
2002
Published online:
19
July
2002
We exposed small size-controlled lead clusters with a few hundreds of atoms to
laser pulses with peak intensities
up to 1015 W cm-2 and durations between 60 fs to 2.5 ps. We
measured kinetic
energies and ionic charge of fragments as a
function of the laser intensity and pulse duration. Highly charged Pb
ions up to n=26 have been detected presenting kinetic energies up
to 15 keV. For comparison with
our experimental results, we have performed simulations
of the laser coupling with a cluster-sized lead nanoplasma using
a qualitative model that was initially proposed by Ditmire and co-workers at
LLNL for the case of rare gas clusters.
From these simulations we conclude that two
mechanisms are responsible for the explosion dynamics of small lead clusters.
As already observed for large rare gas clusters (
), fragments with charge
states below +10 are driven by
Coulomb forces, whereas the higher charged fragments are accelerated by
hydrodynamic forces.
The latter mechanism is a
direct consequence of the strong laser heating
of the electron cloud in the nanoplasma arising from a plasmon-like resonance
occurring at 
. In order to obtain an optimized
laser–nanoplasma coupling, our results suggest that the plasma resonance should
occur at the peak intensity of the
laser pulse. Due to inertial effects, even for such small-sized clusters, the
observed optimum pulse duration is in the order
of 1 ps which is in good agreement with our theoretical results.
PACS: 36.40.Gk – Plasma and collective effects in clusters / 52.50.Jm – Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002
