Nonsequential two-photon double ionization of helium

TL;DR

This paper presents precise ab initio calculations of nonsequential two-photon double ionization of helium, analyzing the effects of electron correlation, pulse parameters, and convergence to improve understanding of this complex quantum process.

Contribution

The study introduces a detailed time-dependent computational approach for double ionization, highlighting the role of electron correlation and pulse characteristics in the process.

Findings

Accurate cross sections for helium double ionization at 40-54 eV.

Insights into the influence of pulse length and shape on ionization yields.

Discussion of convergence and comparison with recent theoretical results.

Abstract

We present accurate time-dependent ab initio calculations on fully differential and total integrated (generalized) cross sections for the nonsequential two-photon double ionization of helium at photon energies from 40 to 54 eV. Our computational method is based on the solution of the time-dependent Schroedinger equation and subsequent projection of the wave function onto Coulomb waves. We compare our results with other recent calculations and discuss the emerging similarities and differences. We investigate the role of electronic correlation in the representation of the two-electron continuum states, which are used to extract the ionization yields from the fully correlated final wave function. In addition, we study the influence of the pulse length and shape on the cross sections in time-dependent calculations and address convergence issues.