Effect of the electron initial longitudinal velocity on the nonsequential double-ionization process

Abstract

The effect of initial longitudinal velocity of the first tunneling electron on the nonsequential double-ionization (NSDI) process is studied using a semiclassical model. Our analysis shows that nonzero initial longitudinal velocity affects two distinct typical trajectories [single-return collision (SRC) and multiple-return collision (MRC)] in the NSDI process in different ways: for SRC, the yield in the center part of the correlation momentum distribution is reduced; for MRC, the tunneling time of the first electron is apparently delayed. In comparison with the case of zero initial longitudinal velocity, the double ionization is suppressed for a long wavelength, and a better agreement with the experimentally observed electron correlation distribution is achieved when the nonzero initial longitudinal velocity is taken into account.

Coulomb Asymmetry in Strong Field Multielectron Ionization of Diatomic Molecules

“…Very recently, this effect of the initial longitudinal momentum of the tunneling electron on its final momentum distribution was also observed in the single ionization of the molecular ion H 2 þ by using a circularly polarized ultrashort laser pulse [28]. Interestingly, the initial longitudinal momentum of the first tunneling electron was found to be important for (e) (f) understanding the entire nonsequential double-ionization process [29].…”

Transition of correlated-electron emission in nonsequential double ionization of Ar atoms

“…It is clear that the electron emission is anticorrelated at lower laser intensities, but becomes correlated as the laser intensity increases. Such a transition is observed in [13,15] and is attributed to quantum tunnelling effect [16,17] or multiple recollision during the ionization process of the second electron [18][19][20]. However, recently we showed that the quantum tunnelling effect is not always important in NSDI [33].…”

“…It has been shown that the longitudinal momentum distribution exhibits an anticorrelation feature at lower laser intensities [13,14], but a correlation feature when the laser intensity is higher than the recollision threshold [15]. Such a transition is attributed to the quantum tunnelling effect [16,17] or the multiple recollision during the ionization process of the second electron [18][19][20]. Here the anticorrelation feature denotes the two electrons emitted back-to-back so that the second and the fourth quadrants of the momentum diagram are highlighted, while the correlation feature means the side-byside emission being dominant.…”

Quantum interference in laser-induced nonsequential double ionization

“…The calculation procedure is based on a wellverified numerical method, which has been employed successfully to understand many aspects of the NSDI process, e.g., the knee structure in the distribution of the yield of double-charged ions versus intensity; the maxima in the 1st and 3rd quadrants of the EMCD etc. [52][53][54][55].…”

“…In this model [52][53][54][55][56], one electron is released at the outer edge of the field-suppressed Coulomb potential through tunneling with a rate given by the ADK formula [57]. The subsequent evolution of the tunneled and the bound electron is determined by Newton's equation of motion (in atomic units, e = m = = 1)…”