Multielectron ionization in O$_2^+$ driven by intense infrared laser pulses

Abstract

We extend a recently developed three-dimensional semiclassical model [\href{https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.033106}{Phys. Rev. \textbf{A} 109, 033106 (2024)}] to study multielectron ionization and the formation of highly excited Rydberg states in O$_{2}^+$ driven by intense infrared laser pulses. Our model fully accounts for the Coulomb interaction between all particles, except for the Coulomb repulsion between bound electrons which is replaced by effective potentials. This replacement overcomes the hurdle of artificial autoinization. In addition, the multielectron motion is treated on an equal footing with nuclear motion, that is, electrons and nuclei are both allowed to move at the same time. We focus on triple and double ionization as well as frustrated triple and double ionization. For these processes, we identify and explain the main features of the sum of the kinetic energies of the final ion fragments resulting from the break-up of O$_{2}^+$. We also describe a physical mechanism that underlies frustrated triple ionization.