Distribution of final momenta with (left) no distinction between electrons, (center and right) recolliding vs. struck, with positive being collision direction. The center and right are split between short and long time delays.

Electron Drift Direction in Strong-Field Double Ionization of Atoms


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 $5 \times 10^{14}$ W cm$^{−2}$ becomes a triplet for wavelength 1314 nm, then a doublet 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.

Journal of Physics B: Atomic, Molecular and Optical Physics 42 134009