Recollision of excited electron in below-threshold nonsequential double ionization

TL;DR

This paper reveals the significant role of recollision between the second electron and the ion in below-threshold nonsequential double ionization, using a Coulomb-corrected quantum-trajectories method to match experimental momentum patterns.

Contribution

It introduces a Coulomb-corrected quantum-trajectories approach to identify the recollision effect between the second electron and the ion, expanding understanding of ionization dynamics.

Findings

Reproduces experimentally observed momentum distributions.

Identifies the transition between cross-shaped and anti-correlated patterns.

Shows the influence of pulse duration on recollision dynamics.

Abstract

Consensus has been reached that recollision, as the most important post-tunneling process, is responsible for nonsequential double ionization process in intense infrared laser field, however, its effect has been restricted to interaction between the first ionized electron and the residual univalent ion so far. Here we identify the key role of recollision between the second ionized electron and the divalent ion in the below-threshold nonsequential double ionization process by introducing a Coulomb-corrected quantum-trajectories method, which enables us to well reproduce the experimentally observed cross-shaped and anti-correlated patterns in correlated two-electron momentum distributions, and also the transition between these two patterns. Being significantly enhanced relatively by the recapture process, recolliding trajectories of the second electron excited by the first- or third-return recolliding trajectories of the first electron produce the cross-shaped or anti-correlated distributions, respectively. And the transition is induced by the increasing contribution of the third return with increasing pulse duration. Our work provides new insight into atomic ionization dynamics and paves the new way to imaging of ultrafast dynamics of atoms and molecules in intense laser field.