Molecular rotation assisted non-sequential double ionization

TL;DR

This paper identifies a new molecular rotation assisted non-sequential double ionization mechanism in H2 molecules under intense laser pulses, highlighting the role of molecular rotation dynamics in electron recollision and ionization processes.

Contribution

It introduces the MR-NSDI mechanism, demonstrating how molecular rotation enhances double ionization probability and involves two distinct ionization channels with different internuclear distance dependencies.

Findings

Molecular rotation significantly boosts NSDI probability.

Two ionization channels with different internuclear distances are identified.

A nuclear emission signature along the laser polarization is linked to MR-NSDI.

Abstract

A molecular rotation assisted non-sequential double ionization (MR-NSDI) mechanism is identified in the breakup of rotational H$_2$ molecules in a few-cycle intense laser pulse using a semi-classical trajectory Monte Carlo method. Applying a molecular source in an appropriate rotational state could intensively boost NSDI probability, and conclude with an additional small anti-correlated electron momentum distribution. It reveals the critical role of the continuous dynamics of molecular rotation, which assists the recollision process and subsequently releases the excited electron from the potential portal resulted from molecular rotation. Two underlying exit channels are found to contribute to MR-NSDI, i.e. tunneling ionization (dominated by enhanced ionization) and direct ionization. The two channels are confirmed to have different critical breakup internuclear distances. A prominent nuclear emission in $(-30^{\circ},30^{\circ})$ along the laser polarized direction is identified to be a signature of MR-NSDI.