Nonsequential double ionization of N-2 in a near-single-cycle laser pulse

We present a comparative study of nonsequential double ionization (NSDI) of N-2 and Ar exposed to near-single-cycle laser pulses. The NSDI process is investigated using carrier-envelope-phase-tagged electron-ion coincidence spectroscopy. The measured NSDI spectra of N-2 and Ar exhibit a striking resemblance. In particular, the correlated two-electron momentum distribution arising from NSDI of N-2 also displays a cross-shape very similar to that reported for Ar [Bergues et al., Nat. Commun. 3, 813 (2012)]. We interpret our results in terms of recollision-excitation with subcycle depletion and discuss how this mechanism accounts for the observed similarities and differences in the ionization behavior of the two species.