Journal of Physics B: Atomic, Molecular and Optical Physics
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 × 1014 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.
Haan, Stanley L.; Smith, Z. S.; Shomsky, K. N.; and Plantinga, P. W., "Electron drift directions in strong-field double ionization of atoms" (2009). University Faculty Publications. 396.