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

Shicheng Jiang,Guanglu Yuan,Ruifeng Lu,Chao Yu,Tong Wu

doi:10.1038/srep42086

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.

Highlights

Packets move to the region of large nuclear distances in a strong field, leading to the dissociation of the molecule
The chosen initial vibrational state ensured that the internuclear distances R within the quasi-periodically vibrating wave packet did not exceed 7 a.u., avoiding charge-resonance-enhanced ionization (CREI)
We could measure the dependences of the dissociation flux, ionization flux, and kinetic-energy release (KER) on the time delay, which can be used to probe the dynamics of molecular ionization and dissociation

Summary

Introduction

Packets move to the region of large nuclear distances in a strong field, leading to the dissociation of the molecule. New possibility has been opened to manipulate directional bond breaking of molecules by strong field They extended experimental measurement to vibrational and orbital resolved electron-nuclear sharing of photon energy for a multielectron CO system even by applying a multicycle laser pulse[49]. These abovementioned studies confirmed the relative influence of electron and nuclear motions. The development of laser technology has allowed the achievement of phase-stabilized few-cycle and mid-infrared laser fields These advanced technologies have been used to study the dynamics of electrons and nuclei. By numerically solving the TDSE in the presence of nuclear-electron correlation, we studied the dissociation and ionization dynamics of quasi-periodically vibrating H2+ using the pump-probe scheme. The primary aim of this paper is to present an elaborate control of molecular dissociation and ionization, as well as to survey the effect of nuclear motion on ionization and especially on the dissociation of H2+, using advanced few-cycle and mid-infrared laser technologies

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