From recollisions to the knee: A road map for double ionization in intense laser fields

TL;DR

This paper investigates the electron-electron collision dynamics in strong laser fields, distinguishing between sequential and nonsequential double ionization, and models the probability trends leading to the characteristic 'knee' in ionization yields.

Contribution

It provides a detailed analysis of recollision processes and introduces a simplified model that captures the intensity-dependent double ionization probability shape.

Findings

Nonsequential ionization probability forms a bell-shaped curve.

Sequential ionization probability increases monotonically with laser intensity.

A simplified model reproduces the 'knee' feature in double ionization yields.

Abstract

We examine the nature and statistical properties of electron-electron collisions in the recollision process in a strong laser field. The separation of the double ionization yield into sequential and nonsequential components leads to a bell-shaped curve for the nonsequential probability and a monotonically rising one for the sequential process. We identify key features of the nonsequential process and connect our findings in a simplified model which reproduces the knee shape for the probability of double ionization with laser intensity and associated trends.