Intensity-dependent dynamics of the correlated electrons in molecular double ionization driven by mid-infrared laser pulses

With the three-dimensional classical ensemble model, we have investigated the complex electron correlations in N2 double ionization by the mid-infrared laser pulses over a wide range of laser intensities. Our numerical results show that the correlated longitudinal electron momentum spectra exhibit rich correlated patterns with the increase of the laser intensity. At the low and high laser intensities, the correlated electron momentum spectra display an obvious finger-like structure, while at the moderate laser intensity the finger-like structure is not observed and there is a certain contribution from the back-to-back emission. By back-analyzing the classical trajectories, the subcycle dynamics of the molecular double ionization in the long-wavelength regime are revealed and the complex electron correlations are explained.