Quantum-state-resolved ionization dynamics induced by x-ray free-electron laser pulses

Sang-Kil Son, Laura Budewig, and Robin Santra

[BibTeX][poster]

Intense x-ray free-electron laser (XFEL) pulses can induce multiple sequences of inner-shell ionization events and accompanying decay processes in atoms, producing highly-charged atomic ions. In general, x-ray multiphoton ionization dynamics have been described in terms of time-dependent populations of the electronic configurations visited during the ionization dynamics, neglecting individual state-to-state transition rates and energies. Combining a state-resolved electronic-structure method based on first-order many-body perturbation theory [1] with a Monte Carlo rate-equation method [2] enables us to study state-resolved dynamics based on time-dependent quantum-state populations. Here we present a theoretical study of state-resolved x-ray multiphoton ionization dynamics of atoms. Our results demonstrate that configuration-based and state-resolved calculations provide similar charge-state distributions, but differences are visible when resonant excitations are involved. Calculated time-resolved spectra of electrons and photons allow us to investigate ultrafast dynamics of x-ray multiphoton ionization in detail. In addition, we will present a comparison with a recent experiment on Ne [3], a theoretical study of electron-cloud alignment dynamics of Ar induced by an XFEL pulse [4], and a discussion of how to handle the extremely large number of atomic parameters involved in state-resolved dynamics calculations via machine-learning techniques [5]. — [1] L. Budewig, S.-K. Son, and R. Santra, Phys. Rev. A 105, 033111 (2022). [2] L. Budewig, S.-K. Son, and R. Santra, Phys. Rev. A 107, 013102 (2023). [3] T. Baumann, S.-K. Son, J.-E. Rubensson, et al., in preparation. [4] L. Budewig, S.-K. Son, and R. Santra, (submitted). [5] L. Budewig, S.-K. Son, Z. Jurek, M. M. Abdullah, M. Tropmann-Frick, and R. Santra, Phys. Rev. Res. 6, 013265 (2024).

Tags: x-ray multiphoton ionization, state-resolved, ionization dynamics, XATOM, CFEL, DESY