Double ionization of hydrogen molecules in a high-intensity linearly polarized laser pulse

The double ionization of a hydrogen molecule in a high-intensity linearly polarized laser pulse is systematically investigated. It is found that the process of the double ionization of the hydrogen molecules is dominated by the sequential double ionization, whereas the spectrum of the electron momentum exhibits an obvious correlation behavior of electrons and this correlation behavior exists with the variation of the nuclear distance. Based on the analysis of electron trajectories, we demonstrate that this correlation is caused by the ultrafast electronic ionization within a quarter optical period of the laser field. Especially, the correlation of the electron momenta depends on the laser pulse's negative vector potential, which is corresponding to the ionization instants of the two electrons.