Natural Lifetimes and Hyperfine Structure for K 39 in the 5p^(2)P_(3/2) and 6p^(2)P_(3/2) Levels of the K I Spectrum by Resonance Scattering of Light

The hyperfine coupling constants and the natural radiative lifetimes of the 5 p 2 P 3/2 and 6 p 2 P 3/2 levels of K 39 were determined in a level crossing experiment on an enriched K 39 sample in a sealed-off resonance cell. The following results were obtained: ----- -- a (5 p 2 P 3/2 ) = 1.973 (12) MHz -- a (6 p 2 P 3/2 ) = 0.886 (8) MHz ----- -- b (5 p 2 P 3/2 ) = 0.870 (18) MHz -- b (6 p 2 P 3/2 ) = 0.370 (15) MHz ----- -- Ï(5 p 2 P 3/2 ) = 133 (3) ns -- Ï(6 p 2 P 3/2 ) = 310 (15) ns ----- Considering the influence of core polarization on the magnetic hyperfine interaction and applying a Sternheimer correction, fairly consistent values of the electric quadrupole moment Q are obtained from the first three levels of the np 2 P 3/2 sequence. We find Q (K 39 ) = +0.059 (6) barn.