Intense-field multiphoton ionization of helium

Abstract

The dynamics of multiphoton ionization of helium are investigated through numerical integration of the two-electron time-dependent Schrödinger equation. Using this work as a benchmark, a new single-active-electron model is introduced that gives agreement with He ionization rates to within a few per cent on average, and gives good agreement with He harmonic generation spectra over a laser intensity range of to , and frequencies corresponding to four- and five-photon ionization.