Branching fractions and transition probabilities for transitions from 2p^4 3p, 2p^4 3d, and 2p^4 4s levels of Ne II

Branching fractions for electric dipole transitions from 2p4 3p,2p4 3d, and 2p4 4s upper levels in singly ionized neon atoms excited in a high-current hollow-cathode lamp were measured. Transition probabilities for many weak intercombination lines were determined for the first time to the authors’ knowledge. The measurements were carried out with two different techniques to minimize the effect of systematic errors, first in an experiment with a 2-m grating monochromator and then with a Fourier transform spectrometer. The uncertainty of the branching fraction data is 4%(1σ) for lines corresponding to LS-allowed transitions and 30%(1σ) for weak intercombination lines. For 14 upper levels complete sets of transitions could be measured that enabled us to determine absolute transition probabilities when lifetime data for the upper levels were available.