title: The contribution of the delayed ionization in strong-field nonsequential double ionization.
abstract: With the classical ensemble model, we have investigated the pulse-duration dependence of nonsequential double ionization (NSDI) over a wide range of laser intensity. The correlated electron momentum distributions are distinctly different for the few-cycle and multiple cycle pulses, which agree well with the previous experiments. Based on this agreement, we analyzed the underlying process for the pulse-duration dependence of the electron correlation by tracing the classical trajectories. Counterintuitively, our analysis shows that the recollision-induced excited states of NSDI could resist ionization in the strong laser field for a time much longer than one optical cycle even at very high intensities. For the multiple-cycle pulses, NSDI events with such a long time delay have significant contribution to the total NSDI yields, which is responsible for the pulse-duration dependence of the observed correlated patterns in the electron momentum distributions.
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Yinbo
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Yueming
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Lan
authors.affiliation: School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
authors.forename: Peixiang
authors.initials: P
authors.lastname: Lu