Fig. 2: Simulated results for below-threshold nonsequential double ionization of Ar.
From: Recollision of excited electron in below-threshold nonsequential double ionization
a–d Simulated correlated electron momentum distributions (CEMDs) of Ar for different laser pulse durations at the intensity of 1.25 × 1014 W cm−2. The carrier-envelope phases are averaged. Each CEMD is normalized to itself. e Simulated yield ratio Y2&4/Y1&3 for different pulse durations and different intensities. Y1&3 (Y2&4) denotes the integrated yield in the first and third (the second and fourth) quadrants in the CEMD. The numbers given in the legends denote peak laser intensities with units of 1014 W cm−2. The open circles are calculated by only considering direct trajectories of e2 (see text for details). f Measured results extracted from Ref. 25. The black short-dashed lines in e and f serve as indications of the intensity dependence.
