DYNAMICAL QUENCHING OF FIELD-INDUCED DISSOCIATION OF H-2(-LASERS() ININTENSE INFRARED)

The dynamics of dissociation of the hydrogen molecular ion H-2(+) in a n intense infrared (IR) field is studied by a series of wave packet si mulations, In these simulations, the molecular ion is assumed to be in stantly prepared at the initial time by a sudden ionization of the gro und-state H-2 parent molecule, and a variety of frequency and intensit y conditions of the laser field are considered. A new stabilization me chanism, called dynamical dissociation quenching, is found operative i n the IR spectral range, In a Lime-resolved picture, this effect is sh own to arise when a proper synchronization between the molecular motio ns and the laser field oscillations is ensured. In the Floquet, dresse d molecule picture, the effect is related to interferences between the Floquet resonances that are excited initially by the nonadiabatic, su dden preparation of the ion. The Floquet analysis of the wave packets in this low frequency regime reveals important intersystem couplings b etween Floquet blocks, reflecting the highly multiphoton character of the dynamics. (C) 1998 American Institute of Physics. [S0021-9606(98)0 0310-9].