Correlated electron dynamics in strong-field double ionization

Abstract

In intense laser-atom/molecule interaction, there are many new phenomena involving multielectron effects. As one of the most important strong-field process, strong-field double ionization of atoms and molecules, especially the strong-field nonsequential double ionization (NSDI), exhibits highly correlated behaviors, providing a clean way to study electron correlation in nature. We review the microscopic electron dynamics of NSDI revealed by recent experimental studies based on the COLTRIMS and the related theory contributions. We summarized the laser intensity-dependent microscopic electron dynamics of NSDI. At low laser intensities, NSDI is dominated by the recollision-excitation with subsequent field ionization, and the time delay between the final ionizations of the two electrons could results in the experimental observed back-to-back emission of the electron pairs. As the laser intensity increases, recollision induced direct ionization dominates NSDI and two electrons ionized almost simultaneously after recollision. In this process the final-state ion-electron attraction and electron repulsion significantly affect the details of the electron correlation pattern. As the laser intensity further increases, the role of final-state ion-electron and electron-electron interactions becomes less important, and the asymmetric energy sharing at recollision is prevalent which accounts for the strange V-like shape in the correlated electron momentum spectra at very high laser intensity. We also introduced the control of the correlated electron dynamics. It has been theoretically predicted that the electron pairs can be controlled to exhibit correlated or anticorrelated behavior with the two-color field, which has been proved by experiment. We also review the progress on strong-field sequential double ionization (SDI). Recent experiments have observed many phenomena which conflicted with the predictions of the previous theoretical models of SDI. Here we introduced a recent developed model of strong-field SDI, which successfully explained the new experimental results and predicted many interesting results.