Precision measurement of the lifetime of the7S13state of atomic mercury

We report the first observation of the atomic cascade $9^{1}P_{1}\ensuremath{-}7^{3}S_{1}\ensuremath{-}6^{3}P_{1}$ in mercury. The exponential distribution of time delays between detection of the $9^{1}P_{1}\ensuremath{-}7^{3}S_{1}$ (5676-\AA{}) photon and the $7^{3}S_{1}\ensuremath{-}6^{3}P_{1}$ (4358-\AA{}) photon was measured, and a value of 8.2(0.2) nsec was obtained for the mean lifetime of the $7^{3}S_{1}$ level.