Anomalous strong-field ionization of oxygen

Summary form only given.Unlike atoms, simple tunneling models for the ionization rates of molecules by strong laser fields often do not agree with experimental data, indicating either a lack of understanding of tunneling ionization or new physics. The latter explanation has been invoked to use the observed low ionisation rate of O/sub 2/ as evidence for dissociative recombination in strong laser fields. While we can show, with new data, that dissociative recombination is not a significant effect for O/sub 2/ we can also show, with a new molecular model, that tunneling ionization also cannot explain the measured rates. This implies that there are still more new phenomena in the strong-field behavior of molecules.