Electron emission from highly charged ions: signatures of magnetic interactions and retardation in strong fields

Abstract

The electron emission of highly charged ions has been reanalyzed with the goal of separating the magnetic and retardation contributions to the electron–electron (e–e) interaction from the static Coulomb repulsion in strong fields. A remarkable change in the electron angular distribution due to the relativistic terms in the e–e interaction is found, especially for the autoionization of beryllium-like projectiles, following a 1s → 2p3/2 Coulomb excitation in collision with some target nuclei. For low-energetic, high-Z projectiles with Tp ≲ 10 MeV u−1, a diminished (electron) emission in the forward direction as well as oscillations in the electron angular distribution due to the magnetic and retarded interactions are predicted for the autoionization of the 1s2s22p3/23P2 resonance into the 1s22s 2S1/2 ground and the 1s22p 2P1/2 excited levels of the finally lithium-like ions, and in contrast to a pure Coulomb repulsion between the bound and emitted electrons. The proposed excitation–autoionization process can be observed at existing storage rings and will provide a novel insight into the dynamics of electrons in strong fields.