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 $\mathrm{Li}2{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ and $\mathrm{Na}3{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ are measured to be (27.29±0.04) and (16.40±0.03) nsec, respectively (uncertainties are one standard deviation).

• Received 7 December 1981

DOI:https://doi.org/10.1103/PhysRevA.26.3351