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

Abstract

The dynamics of dissociation of the hydrogen molecular ion H 2 ϩ in an intense infrared ͑IR͒ 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 time-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.

Attosecond pump-probe transition-state spectroscopy of laser-induced molecular dissociative ionization: Adiabatic versus nonadiabatic dressed-state dynamics

“…Depending on the laser field's frequency and intensity regime, the dynamical and structural changes that the field can cause within the molecule are either of the type associated with the quasistatic picture or that associated with the Floquet picture. The first type of molecular restructuring, operative in the low-frequency (IR) regime, gives rise to the opportunity of controlling molecular dissociation by directly synchronizing molecular wave packets with a time-dependent potential energy barrier to dissociation (the so-called dynamical dissociation quenching (DDQ) effect [14]). For a higher frequency, in the near infrared (NIR) or the visible spectral range, the dissociation dynamics transit through laser-induced resonances defined and supported by cycled-averaged dressed electronic states [15].…”

Controlling Vibrational Wave Packet Motion with Intense Modulated Laser Fields

“…Our work is closely related to intense field midinfrared experiments [1], and the related analysis [8,9]. Although the carrier frequency is higher in our experiment, the vibrational wave packet does not respond to the carrier frequency but to the envelope.…”

Controlling vibrational cooling with zero-width resonances: An adiabatic Floquet approach

“…Quantum control has attracted attention among the physics and chemistry communities [4], but also in applied mathematics for the development of new theoretical methods. In strong field molecular physics, antagonistic basic mechanisms like bond softening versus vibrational trapping [5,6], or barrier lowering versus dynamical dissociation quenching [7] have been referred to in the control scenarios of molecular reactiv-ity or even for alignment/orientation purpose [8]. An even more unexpected quenching mechanism is in relation with the so-called Zero-Width Resonances (ZWR).…”