Double photoelectron emission from He atoms by intense laser pulses with a wave length of $394.5\,nm$ is computed for intensities $3.5 - 9.2\times 10^{ 14}W/cm^2$. Joint momentum distributions confirm the characteristics seen in classical trajectory calculations. The pronounced transition from back-to-back to side-by-side emission with increasing intensity, the $He^{ ++}/He^+$ ratios, and a modulation of joint energy spectra agree well with a recent experiment [Henrichs et al., PRA 98, 43405 (2018)], if one admits an increase of experimental intensities by a factor $\sim 2$. We find that Freeman resonances enhance anti-correlated emission, we identify the signature of electron repulsion in joint angular distributions, and we interpret the modulation of joint energy spectra as a signature of multiple recollsions.
Categories: physics.atom-ph
