Branching fractions for the 5s(2)5p(2)-5s(2)5p6s supermultiplet in the Sn isoelectronic sequence

Recent studies of the Si and Ge isoelectronic sequences have shown that bra nching fractions within the ns(2)np(2)-ns(2)np(n + 1)s supermultiplets are accurately described by a semiempirical model that uses spectroscopic energ y level data to characterize intermediate coupling. It was also recently sh own that a similar model applied to alkaline-earthlike ns(2)-nsnp transitio ns can be advantageously generalized to include the effects of spin-other-o rbit interaction and differences between the singlet and triplet radial wav e functions. These two formalisms are combined, extended, and applied here to obtain a predictive systematization of branching fractions for the 5s(2) 5p(2)-5s(2)5p6s supermultiplet of the ions Sn I-Cs VI in the Sn sequence.