Exploration of strong-field double ionization of CS2 molecule in bichromatic counterrotating circularly polarized laser fields

Abstract

By using classical ensemble method, we investigate the double ionization of CS2 molecule in linearly, the bichromatic counterrotating circularly polarized laser fields and the combination of bichromatic counterrotating circularly polarized laser fields and static field, respectively. The numerical results show that the ionization probability in the bichromatic counterrotating circularly polarized laser fields is about 2 order magnitude higher than that in linearly polarized laser field. When a static field is added, the ionization probability is the largest. Besides, the “knee” structure occurs at about 0.05PW/cm2 in linearly polarized laser field; whereas “knee” structure is disappeared in the bichromatic counterrotating circularly polarized laser fields and combined laser field. The corresponding momentum distribution of CS2 molecule presents a “finger-like” structure at about 0.05PW/cm2 in linearly polarized field. By analysing the energy distributions of double-ionized electrons versus time and corresponding trajectories, we find that, for linearly polarized case non-sequential double ionization (NSDI) is predominant at about 0.05PW/cm2, for bichromatic counterrotating circularly polarized laser fields, one electron ionizes after another which indicate sequential ionization process (SDI). When the static field is added, the two electrons undergoes a long pre-ionization process first and then ionizes one after another, and the pre-ionization process lasts longer than other two cases.