Transition rates for the doublet-quadruplet intersystem lines in C II and N III

Radiative decay rates for the 2s 2 2p 2 P 0 -2s2p 2 4 P intersystem transitions at 233 nm in C + and at 175 nm in N 2+ have been calculated taking configuration interaction (CI) and relativistic effects into account with the help of the computer code SUPERSTRUCTURE. The present physical model yields satisfactory agreement between the calculated probabilities and recent measurements obtained by recording the time dependence of the photon intensities emitted from the metastable levels in the quartet system 2s2p 2 4 P. In particular, the large discrepancies between the new experimental data and previous theoretical results have been considerably reduced in the case of N III.