Efficiency of double ionization of a three-electron atom in moderate laser-field intensities
Phys. Rev. A 112, 033113 – Published 23 September, 2025
DOI: https://doi.org/10.1103/1dn8-4f6h
Abstract
We study double ionization in a one-dimensional model of a three-electron atom exposed to strong short laser fields. The corresponding ab initio simulations reveal a characteristic “knee” in the ionization yield at lower field intensities than in comparable two-electron systems. To understand the origin of this shift, a quantitative semianalytic model for double ionization of a three-electron atom has been created. In this model, ionization is treated as a combination of different scenarios and channels. Each channel is simulated with either quantitative rescattering theory (QRS) or a two-electron ab initio model. Analysis of the semianalytical results indicates that the shifted part of the “knee” is dominated by a recollision-excitation channel in which the rescattering electron initially escapes the parent atom from an inner orbital. This counterintuitive phenomenon is then discussed and explained.
