Strongly driven molecules: Traces of soft recollisions for intermediate intensities in the over-the-barrier regime

Using a three-dimensional quasiclassical technique, we explore double ionization in N-2 when driven by a linearly polarized, infrared (800 nm) long (27 fs) laser pulse. For intensities ranging from the tunneling to the over-the-barrier regime, we identify the double-ionization pathways in a unified way as a function of total final electron energy. Moreover, for intermediate intensities in the over-the-barrier regime we find that the correlated electron momenta have a prevailing square pattern. This square pattern is mainly due to the delayed (one electron is ejected with a delay after recollision) pathway's contribution to double ionization. For intermediate intensities the delayed pathway is dominated by soft recollisions [identified in Phys. Rev. A 80, 053415 (2009)], with the first electron tunneling at large field phases. We expect this square pattern to be absent for high intensities.