Prevalence of different double ionization pathways and traces of three-body collisions in strongly driven Helium

TL;DR

This paper investigates the different double ionization pathways in strongly driven Helium, revealing a new triple collision pathway at low energies and analyzing how these pathways depend on laser parameters.

Contribution

It introduces a unified framework for understanding double ionization pathways in Helium, highlighting the role of three-body collisions and identifying observable signatures.

Findings

Discovery of a new triple collision pathway at low energies.

Identification of asymptotic observables for pathway prevalence.

Dependence of pathways on laser frequency and intensity.

Abstract

We present a unified treatment of the prevalence of different double ionization (DI) pathways as a function of the sum of the final electron energies in strongly driven Helium. We do so as a function of laser frequency and intensity. At small total energy a new DI pathway prevails where both electrons are ionized with a delay after re-collision. We find that three-body collisions between the two electrons and the nucleus underly this pathway--we refer to it as triple collision (TC) pathway. At high total energy the pathway that prevails is the one where one electron is ionized with a delay following re-collision---we refer to it as Delayed pathway. Asymptotic observables that trace the prevalence of the latter pathways are identified.