@article{0953-4075-42-13-134009,
  author={S L Haan and Z S Smith and K N Shomsky and P W Plantinga},
  title={Electron drift directions in strong-field double ionization of atoms},
  journal={Journal of Physics B: Atomic, Molecular and Optical Physics},
  volume={42},
  number={13},
  pages={134009},
  url={http://stacks.iop.org/0953-4075/42/i=13/a=134009},
  year={2009},
  abstract={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 × 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.}
}