Experimental and theoretical values for the lifetimes of the $5s5p{}^1{P}_1$ and ${}^3{P}_1$ levels in the Cd isoelectronic sequence are examined in the context of a data-based isoelectronic systematization. Lifetime and energy-level data are combined to account for the effects of intermediate coupling, thereby reducing the data to a regular and slowly varying parametric mapping. This empirically characterizes small contributions due to spin-other-orbit interaction, spin dependences of the radial wave functions, and configuration interaction, and yields accurate interpolative and extrapolative predictions. Multiconfiguration Dirac-Hartree-Fock calculations are used to verify the regularity of these trends, and to examine the extent to which they can be extrapolated to high nuclear charge.

• Received 18 July 2000

DOI:https://doi.org/10.1103/PhysRevA.62.052513