Fig. 1. (a) n distribution and (b) L distribution of the recaptured electrons. The insert in (a) shows the electric field of the laser pulse and the dashed line indicates the tunneling ionization time in our calculations.

Fig. 2. Probability distribution for FTI in the tunneling coordinate, where t and Py0 stand for the tunneling time and the initial transverse momentum at tunneling, respectively. The colorbar on the right represents the recapture probability.

Fig. 3. Final angular momentum distribution versus the initial transverse momentum of the recaptured electrons at tunneling. The colorbar on the right represents the recapture probability.

Fig. 4. Tunneling time distribution versus the initial transverse momentum for recaptured electrons. The distribution is divided into two parts. (a) shows the regular part (for the events between the dashed lines in Fig. 3) and (b) shows the irregular part (for the events out of the dashed lines in Fig. 3). The colorbar on the right represents the recapture probability.

Fig. 5. Typical trajectories for recaptured electrons where the parent ion is located at the origin. (a) and (b) show regular and irregular trajectories, respectively. The solid part represents the trajectory in the combination of the laser field and Coulomb force. The dashed part stands for the trajectories when the laser pulses are over where only Coulomb interaction guides the evolution of the electron. The red and blue curves denote two trajectories ionized at the same instant but with opposite initial transverse momenta.

Fig. 6. (a) The evolution of angular momentum of an irregular trajectory (the red curve). In the black curve, we have artificially turned off the Coulomb force. (b) The force along the x and y axes felt by the electron.

Fig. 7. Minimum distance between the recaptured electron and parent ion during the recollision for the irregular events. The colorbar on the right represents the recapture probability.