Direct measurements of excited-state lifetimes in Mg, Ca, and Sr†

The lifetimes of the lowest 3S1 states in Mg, Ca, and Sr have been measured. In addition, the lifetimes of a number of excited 1S0 and 1D2 states in Ca have been determined, as well as the lifetime of the 4s4p1P1 state of Ca. The measurements were made by observing the exponential decay of the intensity of the fluorescence emitted from excited states selectively populated by one- and two-step dye-laser excitation. The values obtained for the 3S1 lifetimes were τ(Mg) = (9.7 ± 0.5) ns, τ(Ca) = (11.7 ± 0.6) ns, and τ(Sr) = (12.9 ± 0.7) ns.