Figure 1

Number of VUV photons ($\hslash \omega =12.7\mathrm{e}\mathrm{V}$) absorbed per atom via inverse bremsstrahlung, plotted as a function of time. All atoms within the cluster are assumed to be singly ionized prior to the laser pulse. The average initial kinetic energy of a plasma electron is 0.01 hartree. The laser pulse, having a peak intensity of $7.3\times {10}^{13}\mathrm{W}/{\mathrm{c}\mathrm{m}}^2$, is Gaussian. It is centered at $t=0$; its FWHM is 100 fs. If the electrons are scattered by simple (Debye-screened) Coulomb potentials, only one photon per atom is absorbed from the laser field. About 30 photons are absorbed, however, if a more realistic atomic scattering potential is taken.Reuse & Permissions

Figure 2

Temporal evolution of neutral and ionic populations in a large xenon cluster exposed to an intense VUV laser pulse. The probability of finding a neutral atom in the cluster is $n_0$; $n_1$ and $n_2$ refer to singly and doubly ionized species, respectively. The same laser parameters as in Fig. 1 are used. Plasma screening, which is responsible for efficient double photoionization of xenon, is taken into account. Collisional ionization is not included.Reuse & Permissions

Figure 3

Number of VUV photons absorbed per atom via inverse bremsstrahlung, plotted as a function of peak pulse intensity. In the underlying calculations, coupled rate equations for the neutral and ionic populations as well as for the temperature of the plasma electrons are numerically integrated. Initially, all atoms are in their neutral ground state. The range of intensities shown was explored in the recent cluster experiment at the TESLA Test Facility in Hamburg [5]. The solid line is a linear fit to the numerical data.Reuse & Permissions

Figure 4

Ionic populations resulting from the interaction of a 100-fs long VUV laser pulse with a large xenon cluster. The solid lines are obtained within a simple rethermalization model (please see the text). The dashed bars reflect mass-spectroscopic signal strengths observed for an average cluster size of 1500 atoms, estimated from data in Ref. 5.Reuse & Permissions