Augmented collisional ionization in XUV-cluster interaction*

High charge states have been observed in Xenon cluster interaction with extreme ultraviolet (XUV) radition from an intense HHG source [1]. Mechanisms underlying the observed high charge states from clusters exposed to the VUV regime -- such as enhanced Inverse Bremsstrahlung heating -- do not play a role due to the small XUV wavelength. Our many body molecular dynamics simulations show that high charge states result from augmented collisional ionization processes, and not enhanced photoionization. These arise from additional microscopic effects that have been not been implemented previously. We have included the process of electron-ion recombination, and have calculated the dynamics for long times after the XUV pulse. We find that many of the high charge states that exist in the core would not survive to the detector. \\[4pt] [1] B. F. Murphy, K. Hoffmann, A. Belolipetski, J. Keto, and T. Ditmire, PRL 101, 203401 (2008).