Recent studies of the explosions of atomic clusters driven by high intensity femtosecond laser pulses have shown that at a sufficiently high intensity and fast laser rise time, the clusters can be stripped of all the electrons. The subsequent explosion is caused by the mutual Coulomb repulsion of the remaining ions. Assuming that the sudden inner cluster ionization approximation (SICI) is applicable, at the temporal onset of the Coulomb explosion all of the relevant electrons are already removed from their host atoms and become unbound electrons. Consequently the ions start from near their initial equilibrium positions in the cluster and expand isotropically. This simple model has been widely applied and has been successful in describing the ion energies observed from the explosions of small clusters (< 1000 atoms) with low charge states (like hydrogen and deuterium). Based on a theory developed by Breizman and Arefiev, if ion and electron motion are not separable, a dependence of the resulting ion energies to the laser polarization should occur. This is caused by a lowered average charge along the laser polarization due to electron motion in the external electric field. This thesis shows experimental results observing this effect. Furthermore Last and Jortner recently have proposed, based on particle dynamics simulations that heteronuclear clusters, with a mixture of heavy and light ions under certain conditions will not explode by the simple, equilibrium Coulomb explosion model but that dynamic effects can lead to a boosting of energy of the lighter ejected ions. In this thesis the experimental confirmation of this theoretically predicted ion energy enhancement in methane clusters is presented.Physic
