Vibrationally Resolved Structure In O-2(+) Dissociation Induced By Intense Ultrashort Laser Pulses

Laser-induced dissociation of O-2(+) is studied in the strong-field limit using two independent methods, namely a crossed laser-ion-beam coincidence 3D momentum imaging method and a supersonic gas jet velocity map imaging technique (790 and 395 nm, 8-40 fs, similar to 10(15) W/cm(2)). The measured kinetic energy release spectra from dissociation of O-2(+) and dissociative ionization of O-2 reveal vibrational structure which persists over a wide range of laser intensities. The vibrational structure is similar for O-2(+) produced incoherently in an ion source and coherently by laser pulses. By evaluation of the potential energy curves, we assign the spectral energy peaks to dissociation of the v = 10-15 vibrational states of the metastable a (4)Pi(u) state via the dissociation pathway vertical bar a (4)Pi(u)> --> vertical bar f (4)Pi(g) - 1 omega >-a mechanism equivalent to bond softening in H-2(+).