# Ionization and expansion dynamics of atomic clusters irradiated with short intense VUV pulses - Physics > Atomic and Molecular Clusters

Abstract: Kinetic Boltzmann equations are used to model the ionization and expansiondynamics of xenon clusters irradiated with short intense VUV pulses. Thisunified model includes predominant interactions that contribute to the clusterdynamics induced by this radiation. The dependence of the evolution dynamics oncluster size, $N {atoms}=20-90000$, and pulse fluence, $F=0.05-1.5$ J-cm$^2$,corresponding to intensities in the range, $10^{12}-10^{14}$ W-cm$^2$ andirradiation times, $\leq 50$ fs, is investigated. The predictions obtained withour model are found to be in good agreement with the experimental data. We findthat during the exposure the cluster forms a shell structure consisting of apositively charged outer shell and a core of net charge equal to zero. Thewidth of these shells depends on the cluster size. The charged outer shell islarge within small clusters $N {atoms}=20,70$, and its Coulomb explosiondrives the expansion of these clusters. Within the large clusters$N {atoms}=2500,90000$ the neutral core is large, and after the Coulombexplosion of the outer shell it expands hydrodynamically. Highly charged ionswithin the core recombine efficiently with electrons. As a result, we observe alarge fraction of neutral atoms created within the core, its magnitudedepending on the cluster size.

Author: B. Ziaja, H. Wabnitz, F. Wang, E. Weckert, T. Moeller

Source: https://arxiv.org/