Determination of lifetimes and nonadiabatic correlations from measured dipole polarizabilities

In atomic systems for which the total oscillator strength of excitations from the ground state is dominated by the transition to the lowest resonance level, the f-sum rule provides a bracketing inequality connecting the lifetime τ of that level to the dipole polarizability αd. This relationship has been used previously to deduce αd from τ. It is shown here that improved spectroscopic accuracies now permit this procedure to be inverted, with τ deduced from a value for αd obtained spectroscopically using the core polarization model. A similar quantitative relationship exists connecting the nonadiabatic correlation factor β to τ, and thus also to αd. The method is applied to a recent measurement of αd for Kr6+ to obtain the values τ(4s4p1P1) = 0.096 ± 0.003 ns and β(Kr6+) = 1.71 ± 0.03a50. It is shown that the use of this method to make precision lifetime determinations for a small number of ions in an isoelectronic sequence permits the exploitation of observed semiempirical regularities to specify the lifetimes of all ions in that sequence.