Photon momentum partition in non-sequential double ionization of helium under strong laser field

Abstract

Partition of photon momentum between the electron and atomic core in non-sequential double ionization of helium is investigated. Semi-classical rescattering model is extended, in order to include the motion of the atomic core. Numerical simulation of the 3D dynamics of the atomic system is performed and data of momentum of the electron and atomic core along the laser propagation direction is collected for further study. Analysis shows that the wavepacket of the electron drifts much further along the laser propagation direction than the atomic core due to the enormous mass difference between them, thus the electron transmitting part of its momentum to the atomic core during rescattering. This kind of momentum exchange is closely related to the dynamics of non-sequential double ionization: a simple calculation indicates that sequential double ionization (SDI), recollision impact ionization (RII) and recollision-exicitation with subsequent ionization (RESI) lead to very different final electron momentum.