Dynamical quenching of field-induced dissociation of H2+ in intense infrared lasers

The dynamics of dissociation of the hydrogen molecular ion H-2(+) in an intense infrared (IR) field is studied by a series of wave packet simulations, In these simulations, the molecular ion is assumed to be instantly prepared at the initial time by a sudden ionization of the ground-state H-2 parent molecule, and a variety of frequency and intensity conditions of the laser field are considered. A new stabilization mechanism, called dynamical dissociation quenching, is found operative in the IR spectral range, In a Lime-resolved picture, this effect is shown to arise when a proper synchronization between the molecular motions and the laser field oscillations is ensured. In the Floquet, dressed molecule picture, the effect is related to interferences between the Floquet resonances that are excited initially by the nonadiabatic, sudden preparation of the ion. The Floquet analysis of the wave packets in this low frequency regime reveals important intersystem couplings between Floquet blocks, reflecting the highly multiphoton character of the dynamics. (C) 1998 American Institute of Physics. [S0021-9606(98)00310-9].