Photorecombination of Lithium-like Sc18+ at Threshold: a Challenge for Atomic Structure Theory

Abstract

Absolute rates for photorecombination (PR) of lithium-like Sc18+ ions have been measured at the Heidelberg heavy-ion Test Storage Ring (TSR). The investigated electron energy range covers all DR resonances related to 2s → 2p1/2 and 2s → 2p3/2 Δn = 0 core excitations. Resonances associated with 1s2 2p3/2 10ℓj intermediate states are found at energies between 0 and 0.3 eV. They are measured with an energy resolution reaching down to about 18 meV for the lowest-energy resonances. A comparison between the experimental results and calculations based on relativistic many-body perturbation theory (RMTB) yields a good agreement even though deviations at very low energy could not be explained yet.