Dielectronic recombination for Li+ ions

Dielectronic recombination (DR) was investigated for Li+ + e- collisions using the electron cooler at the Indiana University Cyclotron Facility (IUCF). For Li+ (1s2) ions, DR is expected to occur for relative energies E between 50-60 eV, and for metastable Li+ (1s2s) DR (involving 2s → 2p transitions) should occur for Erel < 1 eV. Also, for Erel, near zero, radiative recombination (RR) (inverse photoelectric effect) is expected. This work is an extension of previous work at IUCF for He+ ions. These light He+ and Li+ ions pose stringent tests of DR theory because the electron-electron interaction, which mediates DR, is stronger compared to electron-nucleus interactions than it is for heavier ions. Additionally, the electron coupling in two-electron Li+ gives rise to angular momentum configurations different from those in He+. In recent measurements at IUCF, the authors have observed DR for both ground-state and metastable Li+ ions; analysis is currently in progress