Mechanism of delayed double ionization in a strong laser field

TL;DR

This paper explains the mechanism behind delayed double ionization in strong laser fields, highlighting the role of recollision-induced excitation and predicting oscillations in ionization yield with laser intensity.

Contribution

It introduces the Recollision-Excitation with Subsequent Ionization pathway and identifies the mechanism regulating the sticky region, advancing understanding of correlated electron dynamics.

Findings

Delayed ionization can last over one laser cycle.

Oscillations in double ionization yield depend on laser intensity.

The inner electron is trapped in a sticky region before ionizing.

Abstract

When intense laser pulses release correlated electrons, the time delay between the ionizations may last more than one laser cycle. We show that this "Recollision-Excitation with Subsequent Ionization" pathway originates from the inner electron being promoted to a sticky region by a recollision where it is trapped for a long time before ionizing. We identify the mechanism which regulates this region, and predict oscillations in the double ionization yield with laser intensity.