Radiative rates of transitions from the 2s2p^{3 5}S°₂ level of neutral carbon

The measured radiative rates of the 2s²2p^{2 3}P_1,2–2s2p^{3 5}S°₂ intercombination transitions in neutral carbon reported in the literature are critically evaluated by comparing them with theoretical and semi-empirical results. The experimental and theoretical values are compared for the carbon isoelectronic sequence from neutral carbon to nine-times ionized phosphorous. We find strong support for the currently recommended theoretical data on C i and conclude that the published measurements for this transition in neutral carbon cannot be trusted. The reasons for the discrepancies are not clear, and new experiments are needed. (paper)