Laser-induced nonsequential double ionization of helium: classical model calculations

Abstract

We have investigated the double ionization of helium induced by 45 fs, 394 nm linearly polarized laser pulses for intensities (2.5–150) × 1014 W cm−2. The time evolution of the process was determined by applying the classical ensemble approximation (CEA) model. The results of the calculations obtained for the double-to-single ionization ratio, the momentum distribution of the He2+ recoil ion and the correlated two-electron momentum distribution are compared with the recent experimental data of Henrichs et al (2018 Phys. Rev. A 98 043405). The standard CEA model failed to reproduce the basic features of the experiment. A considerable improvement in the description of the experimental data was achieved by including a two-step process in the model: the formation of a transient double excited state in the first step, and the simultaneous release of the two electrons via ‘over the barrier ionization’ in the second step.

Study of the effect of higher-order dispersions on photoionisation induced by ultrafast laser pulses applying a classical theoretical method

“…Later CTMC was generalised for multielectron atoms 35 , and was proved to be a useful method to describe ion-atom collisions 36 – 40 . Although numerous works dealing with soft-Coulomb potential 41 – 48 , as it was pointed out by Sarkadi 49 the screened potential 50 is in better agreement with the results obtained by quantum mechanical calculations. In the present work the applied screened potential for the electron-core interaction was chosen as where is written as Here Z means the nuclear charge of the target, N is the number of electrons in the target atom 51 .…”

Collisional Classical Dynamics at the Quantum Scale

“…The model was recently adapted to study the NSDI of He by short intense laser pulses [150]. This model has been extended to study the correlated electron emission in NSDI of Ar by fewcycle pulses (a = 1.5 a.u.…”