Experimental study of weak intersystem lines and related strong persistent lines of Ne II

We operated a high-current hollow cathode discharge in pure neon at pressures from 93 to 173 Pa and measured the branching fractions of Ne II emission lines originating from several 2p5 3p, 3d, and 4f levels, for which lifetime data were available in the literature. This allowed the determination of transition probabilities for all downward transitions, which included a number of weak intersystem lines. We focused our study on these weak lines, using care to assure correct identifications and accurate intensity measurements, in spite of the presence of much stronger other lines in their vicinity. In contrast to an earlier experiment, we achieved close agreement with a recent multiconfiguration Hartree-Fock calculation