Accurate lifetime measurements of the lowest /sup 2/P/sub 1/2/ states in neutral lithium and sodium

By observing the decay in flight of laser-excited atoms in a fast atomic beam with energy between 60 and 150 keV, lifetimes of the Li 2/sup 2/P/sub 1/2/ and Na 3/sup 2/P/sub 1/2/ are measured to be (27.29 +- 0.04) and (16.40. +- 0.03) nsec, respectively (uncertainties are one standard deviation).