Non-Sequential Double Ionization by Counter Rotating Circularly Polarized Two-Color Laser Fields

TL;DR

This paper investigates non-sequential double ionization of argon atoms using a specialized two-color laser setup with circular polarization, revealing how electron recollision dynamics are controlled by laser parameters.

Contribution

It demonstrates control over double ionization via two counter rotating circularly polarized fields and elucidates the role of recolliding electrons in the process.

Findings

Double ionization probability depends on the relative intensity of the two fields.

A 'knee'-like structure in ionization probability indicates a threshold behavior.

Electron momentum distributions reveal recollision and intermediate excited states.

Abstract

We report on non-sequential double ionization of Ar by a laser pulse consisting of two counter rotating circularly polarized fields (390 nm and 780 nm). The double ionization probability depends strongly on the relative intensity of the two fields and shows a "knee"-like structure as function of intensity. We conclude that double ionization is driven by a beam of nearly monoenergetic recolliding electrons, which can be controlled in intensity and energy by the field parameters. The electron momentum distributions show the recolliding electron as well as a second electron which escapes from an intermediate excited state of Ar$^+$.