Hyperfine Structure Measurements on Plutonium-239

Abstract

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 $^{7}F$ term arising from the configuration ${(5f)}^{6}{(6d)}^{0}{(7s)}^{2}$. Atomic and hyperfine structure constants for this level are found to be $I=\frac{1}{2}$, $J=1$, ${g}_{J}=1.4975\ifmmode\pm\else\textpm\fi{}0.0010$, $\ensuremath{\Delta}\ensuremath{\nu}=7.683\ifmmode\pm\else\textpm\fi{}0.060$ 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 \ifmmode\pm\else\textpm\fi{}0.02 nm under the assumption that the $J=1$ level under investigation arises from a pure $^{7}F$ term belonging to the configuration ${(5f)}^{6}$.