Femtosecond ionization of magnesium clusters grown in ultracold helium droplets T. Döppner, Th. Diederich, J. Tiggesbäumker and K. H. MeiwesBroer Eur. Phys. J. D, 16 1-3 (2001) 13-16 Published online: 15 September 2001 DOI: 10.1007/s100530170049