Streaking single-electron ionization in open-shell molecules driven by X-ray pulses

TL;DR

This paper develops a method to calculate continuum wavefunctions for open-shell molecules in the Hartree-Fock framework, enabling control and analysis of single-electron ionization dynamics driven by X-ray pulses and IR streaking.

Contribution

It introduces a novel approach to model continuum states in open-shell molecules considering spin symmetry, facilitating detailed study of electron escape during X-ray ionization.

Findings

Controlled electron escape angles by varying phase delay between X-ray and IR pulses.

Identified features of electron momentum distributions related to X-ray ionization.

Demonstrated the influence of IR pulse intensity on electron dynamics.

Abstract

We obtain continuum molecular wavefunctions for open-shell molecules in the Hartree-Fock framework. We do so while accounting for the singlet or triplet total spin symmetry of the molecular ion, that is, of the open-shell orbital and the initial orbital where the electron ionizes from. Using these continuum wavefunctions, we obtain the dipole matrix elements for a core electron that ionizes due to single-photon absorption by a linearly polarized X-ray pulse. After ionization from the X-ray pulse, we control or streak the electron dynamics using a circularly polarized infrared (IR) pulse. For a high intensity IR pulse and photon energies of the X-ray pulse close to the ionization threshold of the $1{\sigma}$ or $2{\sigma}$ orbitals, we achieve control of the angle of escape of the ionizing electron by varying the phase delay between the X-ray and IR pulses. For a low intensity IR pulse, we obtain final electron momenta distributions on the plane of the IR pulse and we find that many features of these distributions correspond to the angular patterns of electron escape solely due to the X-ray pulse.