Dielectronic recombination of lithiumlike beryllium: A theoretical and experimental investigation

Recombination spectra of lithiumlike Be ions, taken at the ion storage ring CRYRING, have been investigated with high-energy resolution. The absolute recombination rate coefficient is measured in the center-of-mass energy range 0-5 eV that covers all Deltan=0 core excitations. The results are compared with ab initio calculations and show very good agreement in the resonance energy positions. They also agree in the resonance strengths, except close to the 2s(1/2)-->2p(1/2,3/2) core excitation limit and at the zero center-of-mass energy limit. In the first case the calculated rate coefficient exceeds that of the experiment by up to a factor of 1.7 and in the second it undervalues the experiment by 3.1. Interference effects of direct radiative recombination and recombination via doubly excited states are discussed.