Hyperfine-dependent lifetimes in Be-like ions

Theoretical investigations of hyperfine quenching of the two metastable levels 1s(2)2s2p P-3(0) and P-3(2) have been performed along the Be-like isoelectronic sequence for ions between Z=6-22. It is shown that the lifetime of the latter level is sensitive to hyperfine quenching in the beginning of the isoelectronic sequence, but the sensitivity decreases towards the high-Z end. It is also shown that the hyperfine dependent branching fraction between the 2s(2) S-1(0)-2s2p P-3(2) and the 2s2p P-3(1)-2s2p P-3(2) transitions can lead to some rather drastic changes in the spectra. Our predicted value of 0.677 s(-1) for the hyperfine-induced 2s(2) S-1(0)-2s2p P-3(0) transition rate for Ti-47(18+) are in disagreement with a recent experimental value of 0.56(3) s(-1). Our calculated values of this quenching are in agreement with other recent calculations all along the sequence.