Light-induced vibrational structure in H2+ and D2+ in intense laser fields.

Abstract

Molecular bond-softening and above-threshold dissociation of ${\mathrm{H}}_{2}^{+}$ and ${\mathrm{D}}_{2}^{+}$ in intense laser fields is reexamined using 160 fs pulses of 769 nm light. At intensities greater than \ensuremath{\sim}${10}^{13}$ W/${\mathrm{cm}}^{2}$ new features appear in the dissociation spectrum. These are consistent with the formation of trapped population in light-induced vibrational states, formed in the adiabatic potential near the three-photon resonance between the 1s${\mathrm{\ensuremath{\sigma}}}_{\mathit{g}}$ and 2p${\mathrm{\ensuremath{\sigma}}}_{\mathit{u}}$ states. Rovibrational structure of such light-induced states appears in the kinetic energy spectra of the ion fragments detected after multiphoton ionization.