Lifetime of the(6s26p7s)P1∘1State in Lead

Hanle-effect studies have been made in the $\left(6\mathrm{}{s}^{2}6p7s\right){}_{}{}^1{}_{}{}^{}{P}_1_{}^{\circ }{}_{}{}^{}$ state of lead. ${\mathrm{Pb}}^{208}$ atoms were excited to this state by 2022-Å lead resonance light, and the 5005-Å cross-fluorescent line from this state was detected. The width of the level-crossing signal corresponds to a lifetime for this state of 4.99(15)×${10}^{-9\mathrm{}}$ sec, where the quoted uncertainty is three times the standard deviation. This value is a factor of 4 longer than the value calculated from the oscillator strengths of Corliss and Bozman.