DIELECTRONIC RECOMBINATION OF LITHIUM-LIKE AR-15+

Dielectronic recombination (DR) of Ar15+(1s(2)2s) ions was studied in a single-pass merged-beams experiment at the UNILAC (universal linear accelerator) of GSI. Absolute recombination rates and cross sections were measured for electron-ion center-of-mass energies from 0 to 580 eV. A number of Rydberg states formed by DR with 2s --> 2p (DELTAn = 0) and 2s --> 3l (DELTAn = 1) core excitations and even individual terms in the Is(2)3l3l' configuration could be. resolved. Theoretical calculations of DR cross sections are in good overall agreement with the data. In the calculations for DELTAn = 0 transitions' effects of electric fields have to be included to reproduce the magnitude of the measured DR rates at the limit of the 2pl/2nl and 2p3/2nl Rydberg series. Discrepancies between theory and experiment are observed at the series limits of the (1s(2)3lnl') Rydberg series.