Dissociation and Ionization of Quasi-Periodically Vibrating H2+ in Intense Few-Cycle Mid-Infrared Laser Fields

Abstract

Using quantum mechanics calculations, we theoretically study the dissociation and ionization dynamics of the hydrogen-molecule ion in strong laser fields. Having prepared the nuclear wave packet of H2+ in a specific vibrational state, a pump laser is used to produce a vibrational excitation, leading to quasi-periodical vibration without ionization. Then, a time-delayed few-cycle laser is applied to trigger the dissociation or ionization of H2+. Both the time delay and the intensity of the probe laser alter the competition between dissociation and ionization. We also explore the dependence of kinetic-energy release spectra of fragments on the time delay, showing that the channels of above-threshold dissociation and below-threshold dissociation are opened and closed periodically. Also, dissociation from different channels is influenced by nuclear motion. The dissociation mechanism has been described in detail using the Floquet picture. This work provides a useful method for steering the electronic and nuclear dynamics of diatomic molecules in intense laser fields.

Benchmark Rovibrational Linelists and Einstein A-coefficients for the Primordial Molecules and Isotopologues

“…The deviations between the present linelist and that of Coppola et al (2011) of dozens of cm −1 can probably be attributed to the inaccuracy of their non-adiabatic corrections, as well as the procedure of using the adiabatic corrections taken from Esry & Sadeghpour (1999), which are not equivalent to the ab initio DBOC. On the other hand, the larger error that appears for higher states and affects both their and our calculations is most certainly due to an avoided crossing similar to that appearing in H 2 + at R 6  au (Jiang et al 2017). The error becomes particularly significant for vibrational levels with a v equal and larger than 18.…”

Spin–Orbit State-Selective C–I Dissociation Dynamics of the CH3I+ X̃ Electronic State Induced by Intense Few-Cycle Laser Fields

“…Early investigations of strong-field laser-molecule interactions focused on the simplest molecule, H2 + , whose dissociation in intense laser fields has been extensively studied by both experiment and theory. [10][11][12][13][14][15] These studies elucidate new phenomena such as bond softening, bond hardening and Coulomb explosion. Beyond H2 + , efforts have been undertaken to unravel the interaction of strong laser fields with multielectron molecules.…”

“…The realization of various strong-field control schemes requires an understanding of how molecules interact with laser fields in the nonperturbative, strong-field regime. Early investigations of strong-field laser–molecule interactions focused on the simplest molecule, H 2 + , whose dissociation in intense laser fields has been extensively studied by both experiment and theory. − These studies elucidate new phenomena such as bond softening, bond hardening, and Coulomb explosion. Beyond H 2 + , efforts have been undertaken to unravel the interaction of strong laser fields with multielectron molecules. − Compared to the case of H 2 + , these studies reveal complex angle-dependent ionization yields, , participation of multiple channels in strong-field ionization, , multielectron nonadiabatic dynamics, , and a variety of molecular dynamics. , Recent investigations have also unraveled the time scales for strong-field dissociative ionization, − a key parameter in the understanding of ultrafast photochemical reactions …”

Comparison between the analysis of the asymptotic wavepacket and the associated flux for the calculation of kinetic‐energy‐releases function

“…The latter can be regarded as a time‐dependent analysis, in which the dissociation wavepacket is propagated through a reference point in the asymptotic region and during the propagation, the kinetic‐energy‐dependent flux at the reference point is cumulated to obtain the final distribution probability (see, for example, Refs. ). For simplicity, we term the former “projection method” and the latter “flux method.” To the best of our knowledge, the comparison between the two methods is seldom reported.…”