Classical Trajectory Diagnosis of Finger-Like Pattern in the Correlated Electron Momentum Distribution for Helium Double Ionization

With a semiclassical quasistatic model we identify the distinct roles of nuclear Coulomb attraction, final state electron repulsion and electron-field interaction in forming the finger-like (or V-shaped) pattern in the correlated electron momentum distribution for Helium double ionization [Phys. Rev. Lett. \textbf{99}, 263002; \emph{ibid}, 263003 (2007)]. The underlying microscopic trajectory configurations responsible for asymmetric electron energy sharing after electron-electron collision have been uncovered and corresponding sub-cycle dynamics are analyzed. The correlation pattern is found to be sensitive to the transverse momentum of correlated electrons.