Coherent and stochastic contributions of compound resonances in atomic processes: Electron recombination, photoionization, and scattering

Abstract

In open-shell atoms and ions, processes such as photoionization, combination (Raman) scattering, electron scattering and recombination, are often mediated by many-electron compound resonances. We show that their interference (neglected in the independent-resonance approximation) leads to a coherent contribution, which determines the energy-averaged total cross sections of electron-and photon-induced reactions obtained using the optical theorem. In contrast, the partial cross sections (e.g., electron recombination, or photon Raman scattering) are dominated by the stochastic contributions. Thus, the optical theorem provides a link between the stochastic and coherent contributions of the compound resonances. Similar conclusions are valid for reactions via compound states in molecules and nuclei.

Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

“…In this case one might predict a stronger effect from the angular momentum quantum numbers due to the selection rules in play. In the future our levelresolved statistical theory can also be applied to other processes where chaotic mixing plays an important role, such as photo-and electron-impact ionization and scattering processes in highly charged ions [20]. [14] (black) and the theoretical results of this paper (red).…”

“…Therefore, the problem reduces to calculation of capture into the doorway states, or equivalently, the autoionization rate of the doorways. Further discussion of the role of doorway states in stochastic processes in quantum chaotic systems including atoms, molecules, and nuclei can be found in [20].…”

High magnetic fields for fundamental physics

“…Sufficiently complex elements have spectra with chaotic properties [120][121][122]. The analysis techniques necessary for understanding these spectra bridge many disciplines, ranging from collisions in ultracold atoms [123] to dielectronic recombination (a process where an electron is captured by an atom and this capture is accompanied by excitation of a initially bound electron) [124] and the spectra of nuclei. Chaotic systems are particularly sensitive to small perturbations and can be used to study fundamental interactions and search for new physics beyond the standard model.…”

Quantum chaos in ultracold collisions betweenYb(1S0)andYb(3P2)Green1, Vaillant2, Frye3 et al. 2016Phys. Rev. A162110View full textAdd to dashboardCite

“…These include nuclear energy levels [8], spectra of complex atoms [9,10] and ions [11] and Rydberg spectra of hydrogen atoms in large magnetic fields [12]. The statistics that are most commonly studied include the distribution of nearest-neighbor level spacings and the level number variance [7,13].…”