Classical Trajectory Perspective on Double Ionization Dynamics of Diatomic Molecules Irradiated by Ultrashort Intense Laser Pulses

TL;DR

This paper introduces a semiclassical model to study double ionization in diatomic molecules under intense laser pulses, revealing the influence of molecular alignment and sub-cycle dynamics, with results matching experimental data.

Contribution

The paper presents a novel semiclassical quasi-static model that captures the correlated electron dynamics and molecular alignment effects in double ionization processes.

Findings

Molecular alignment significantly affects double ionization yield.

Classical trajectories reveal sub-cycle ionization dynamics.

Model achieves quantitative agreement with experimental data.

Abstract

In the present paper, we develop a semiclassical quasi-static model accounting for molecular double ionization in an intense laser pulse. With this model, we achieve insight into the dynamics of two highly-correlated valence electrons under the combined influence of a two-center Coulomb potential and an intense laser field, and reveal the significant influence of molecular alignment on the ratio of double over single ion yield. Analysis on the classical trajectories unveils sub-cycle dynamics of the molecular double ionization. Many interesting features, such as the accumulation of emitted electrons in the first and third quadrants of parallel momentum plane, the regular pattern of correlated momentum with respect to the time delay between closest collision and ionization moment, are revealed and successfully explained by back analyzing the classical trajectories. Quantitative agreement with experimental data over a wide range of laser intensities from tunneling to over-the-barrier regime is presented.