Breit interaction effects on the Kα angular distribution following the dielectronic recombination of high-Z ions

Abstract

The angular distribution of the Kα hypersatellite radiation has been investigated for high-Z, helium-like ions following the K−LL dielectronic recombination of initially hydrogen-like projectiles in relativistic ion–atom collisions. A particular strong effect is found for the alignment of the 2s2p1/2J=1 (spin-forbidden) resonance that changes sign if, in addition to the static Coulomb repulsion, the Breit interaction is taken into account for the resonant electron capture. This change in the alignment of the recombined ion also leads to a remarkable shift in the angular distribution of the subsequent 2s2p1/2J=1→1s2s J=0 Kα2 photons from a dominantly perpendicular emission to one that occurs in parallel with the ion beam, and vice versa for the 2s2p1/2J=1→1s2s J=1 line.