Paper XXIX

Radiative rates for transitions within the $n=2$ complex in ions of the boron isoelectronic sequence

M.E. Galavis, C. Mendoza and C.J. Zeippen

Astronomy & Astrophysics Supplement Series, 1998, Vol.131, pp.499-522

As part of the IRON Project, radiative rates have been calculated for the E1, E2 and M1 transitions within the $n=2$ complex in ions of the boron isoelectronic sequence ($6\le Z \le 28$). The computations have been carried out with the atomic structure code SUPERSTRUCTURE which facilitates the generation of extended radiative datasets including configuration interation, Breit-Pauli relativistic contributions and semi-empirical term-energy corrections. By means of extensive comparisons with the available datasets for this sequence, with detailed single-ion calculations and recent experiments, we have been able to assign accuracy ratings to the present A-values. We find that in general the spin-allowed and spin-forbidden E1 transitions are accurate to 10% and 20%, respectively, except for a few transitions in ions with $Z\le 7$ that are perturbed by admixture with low-lying $n=3$ states (e.g. 2s$^2$n$l$) and for those affected by the avoided crossing of the 2s2p$^2$ $^2$S$_{1/2}$ and $^2$P$_{1/2}$ which takes place at $Z\approx 22$. It is concluded that, statistically, the present dataset is the most accurate to date for this astrophysically relevant sequence.