| Abstract | For two-electron diatomic molecules, we investigate magnetic field effects in nonsequential double ionization where recollisions prevail. We do so by formulating a three-dimensional semiclassical model that fully accounts for the Coulomb singularities and for magnetic field effects during time propagation. Using this model, we identify a prominent signature of nondipole effects. Namely, we demonstrate that the recolliding electron backscatters along the direction of light propagation. Hence, this electron escapes opposite to the direction of change in momentum due to the magnetic field. This is in striking contrast to strongly driven atoms where the recolliding electron forward scatters along the direction of light propagation. We attribute these distinct signatures to the different gate that the magnetic field creates jointly with a soft recollision in molecules compared to a hard recollision in atoms. These two different gates give rise, shortly before recollision, to different momenta and positions of the recolliding electron along the direction of light propagation. As a result, we show that the Coulomb forces from the nuclei act to backscatter the recolliding electron in molecules and forward scatter it in atoms along the direction of light propagation. |
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