title: Nonlinear ionization of organic molecules in high intensity laser fields
abstract: We use a series of 23 organic molecules to study ionization of complex media caused by their interaction with intense 40 fs, 0.8 &mgr;m pulses. All molecules reach saturated ionization at higher intensities than would be expected for atoms of the same ionization potential, reminiscent to what has been reported for dielectric breakdown with femtosecond pulses. Dependence of the ionization rate on the alignment of the molecule with the laser field is ruled out as the cause of the high saturation intensities. All molecules allow a significant range of intensities between the region of approximately 100% ionization and before the second and subsequent electrons are removed.
authors.affiliation: Femtosecond Science Program, Steacie Institute for Molecular Science, National Research Council, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6.
authors.initials: SM
authors.lastname: Hankin
authors.initials: DM
authors.lastname: Villeneuve
authors.initials: PB
authors.lastname: Corkum
authors.initials: DM
authors.lastname: Rayner