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A: Fachverband Atomphysik

A 10: Collisions, scattering and correlation phenomena

A 10.2: Vortrag

Dienstag, 10. März 2020, 14:30–14:45, a320

Two-center electron-impact ionization via collisional excitation-autoionization — •Fiona Grüll, Alexander B. Voitkiv, and Carsten Müller — Institut für Theoretische Physik I, Heinrich-Heine-Universität Düsseldorf

Electron-impact ionization of an atom can be strongly influenced by the presence of a neighbour atom. We study electron-impact ionization via excitation-autoionization in a two-center atomic system consisting of atoms A and B. First, collisional excitation of the neighbouring atom B occurs by high-energy electron impact. Afterwards, the excitation energy is transferred radiationlessly via a two-center Auger process to the other atom or ion, leading to its ionization, whereas atom B returns into its initial state. In contrast to other processes creating an autoionizing two-center state by electron impact [1,2], the incident electron in resonant two-center electron-impact ionization 2C(e,2e) leads to excitation – rather than ionization – of atom B. We show that, due to resonant 2C(e,2e), electron-impact ionization can be qualitatively modified and strongly enhanced by several orders of magnitude in a narrow range of emitted electron energies. As a consequence, resonant 2C(e,2e) can provide a substantial contribution to the total electron-impact ionization cross section of atom A and can also lead to changes in the angular distribution of ejected electrons [3].

[1] S. Yan et al., Phys. Rev. A 97, 010701(R) (2018).

[2] X. Ren et al., Nature Commun. 7, 11093 (2016).

[3] F. Grüll, A. B. Voitkiv and C. Müller, Phys. Rev. A 100, 032702 (2019)