Electron Drift Directions in Strong-Field Double Ionization of Atoms

TL;DR

This paper investigates how electron drift directions in non-sequential double ionization of helium vary with laser wavelength, revealing a transition from doublet to triplet structures in momentum spectra due to post-ionization impulses.

Contribution

It provides a detailed analysis of electron drift behavior across different wavelengths using a classical ensemble model, highlighting the impact of laser parameters on ionization spectra.

Findings

Doublet structure at 800 nm becomes a triplet at 1314 nm.

At 2017 nm, the spectra revert to a doublet with a plateau.

Post-ionization impulse determines electron drift direction.

Abstract

Longitudinal momentum spectra and electron drift directions are considered for several laser wavelengths in Non-Sequential Double Ionization of helium using three dimensional classical ensembles. In this model, the familiar doublet for wavelength 800 nm and intensities of order 0.5 PW/cm^2, becomes a triplet for wavelength 1314 nm, then a doublet with plateau for 2017 nm. The results are explained based on whether the post-ionization impulse from the laser results in backward drift for one or both electrons.