  Semi-classical molecular dynamics simulations of small rare gas clusters in
short laser pulses of 100 nm wavelength were performed. For comparison, the
cluster response to 800 nm laser pulses was investigated as well. The inner
ionization dynamics of the multi-electron atoms inside the cluster was treated
explicitly. The simulation results underpin that at XUV wavelengths collisions
play an important role in the energy absorption. The generation of the
surprisingly high charge states of Xe atoms inside clusters, as they were
observed in the free-electron laser experiment at DESY, Hamburg, Germany
[Wabnitz et al., Nature 420, 482 (2002)], is due to the reduced ionization
potential of atoms inside charged clusters, the ionization ignition mechanism,
and collisions.
