Intercombination and resonance transitions in the Zn sequence: problems in experiment and theory

Beam-foil lifetime data on the intercombination line 4 s 2 1 S 0 -4 s 4 p 3 P 1 0 in the Zn-like ions are reviewed and compared to various theoretical predictions. These predictions spread by about a factor of three. After massive corrections for experimental term energies and singlet-triplet splittings, this spread is reduced to a much narrower band, and most of the predictions then agree with the experimental lifetime findings and with the trend predicted by calculations which explicitly take core polarization into account. A screening parameterization of the experimental lifetime and term structure data can then be used to represent singlet and triplet resonance level lifetimes by a single, common curve.