Branching Fractions for the 5s25p2– 5s25p6s Supermultiplet in the Sn Isoelectronic Sequence

Recent studies of the Si and Ge isoelectronic sequences have shown that branching fractions within the ns2np2–ns2np(n + 1)s supermultiplets are accurately described by a semiempirical model that uses spectroscopic energy level data to characterize intermediate coupling. It was also recently shown that a similar model applied to alkaline-earthlike ns2–nsnp transitions can be advantageously generalized to include the effects of spin-other-orbit interaction and differences between the singlet and triplet radial wave functions. These two formalisms are combined, extended, and applied here to obtain a predictive systematization of branching fractions for the 5s25p2–5s25p6s supermultiplet of the ions Sn I–Cs VI in the Sn sequence.