Lifetime measurements in the excited S states of K, Rb, and Cs by the cascade Hanle effect*

The cascade Hanle-effect technique has been described in detail. It has been used to measure the radiative lifetimes of several excited S states in heavy alkali metal atoms. We obtained the following measurements (in nanoseconds): τ(K, 6 2S1/2) = 68 ± 9, τ(Rb, 7 2S1/2) = 91 ± 11, τ(Cs, 8 2S1/2) = 96 ± 14, and τ(Cs, 9 2S1/2) = 231 ± 35.