Vibrationally resolved structure in O2+ dissociation induced by intense ultrashort laser pulses

Abstract

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, ∼10 15 W/cm2 ). The measured kinetic energy release spectra from dissociation of O+ 2 and dissociative ionization of O2 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 ��u state via the dissociation pathway |a 4 ��⟩ → |f 4 ��− 1ω⟩—a mechanism equivalent to bond softening in H+.