Hyperfine structure of Pu I

A theoretical analysis is given of the hyperfine structures of the levels of the multiplet 7 F of Pu I 5f 6 7s 2 . Allowance is made for the effects of intermediate coupling. It is found that the results are consistent with a value of +0.17 ±0.4 nuclear magnetons for the nuclear moment of 239 Pu, provided a term representing the polarization of the core is included. The calculated moment is in good agreement with previous measurements on Pu II 5f 6 7s; furthermore, the magnitude of the core polarization is consistent with that required to account for the anomalous atomicbeam results for Am I 5f 7 7s 2 8 S 7/2 .