Experimental Transition Probabilities for Intercombination Lines in N IV, O V and F VI

Lifetime measurements using the beam-foil method are reported for the 2 s 3 p 3 P 0, 1, 2 levels in N IV, O V and F VI. The 3 P 1 level lifetime is significantly shorter than those for 3 P 0 and 3 P 2 . This is due to the 2 s 2 1 S 0 -2 s 3 p 3 P 1 intercombination transition. From careful lifetime measurements at several ion energies we obtain transition probabilities of (3.3 ± 2.7) × 10 6 , (22 ± 6) × 10 6 and (88 ± 9) × 10 6 s -1 for this spin-forbidden transition in N IV, O V and F VI, respectively. These results are supported by theoretical analyses.