Hyperfine Structure Measurements on Plutonium-239

The atomic hyperfine structure of plutonium-239 has been investigated by the atomic-beam magnetic resonance method. Research has centered about a relatively highly populated electronic energy level having unit angular momentum which is probably the first excited state of a ground-state ⁷F term arising from the configuration (5f)⁶(6d)⁰(7s)². Atomic and hyperfine structure constants for this level are found to be I=1/2, $J=1$, gJ=1.4975±0.0010, Δν=7.683±0.060 Mc/sec.From the measured hyperfine structure separation and $5f$ wave functions derived from a Hartree relativistic calculation, the nuclear magnetic moment is inferred to be ±{}0.02 nm under the assumption that the $J=1$ level under investigation arises from a pure ⁷F term belonging to the configuration (5f)⁶.