Atomic data from the IRON Project - XXXIII. Radiative rates for the intercombination transitions in the carbon isoelectronic sequence

Radiative decay rates are computed with the atomic structure code SUPERSTRU CTURE for the 2s2p(3) S-5(2)o - 2s(2)2p(2) P-3(1), P-3(2) and D-1(2) interc ombination transitions of the carbon isoelectronic sequence (6 less than or equal to Z less than or equal to 28). Contributions from configuration int eraction and relativistic corrections are carefully studied, in particular the spin-spin interaction that is shown to be of considerable importance fo r low Z. By extensive comparisons with other theoretical datasets and measu rements of the S-5(2)o radiative lifetime and the B = A(S-5(2)o - P-3(2))/A (S-5(2)o - P-3(1)) branching ratio, rye are able to assign accuracy ratings to the present transition probabilities. The transitions to the ground ter m are believed to be accurate to better than 10% whereas the smaller A-valu es belonging to transitions to the D-1(2) are not expected to be accurate t o more than 20%.