The Nuclear Magnetic Moment of Lanthanum

The hyperfine structure of some twenty-five lines has been investigated in order to determine the absolute overall widths of each member of the $5d^{2}6s{}_{}{}^4{}_{}{}^{}F$ levels. From these a nuclear $g$-factor of 0.719 and a magnetic moment of 2.5 small magnetons have been computed. The Landé interval rule applied to the hyperfine structure of a three-electron configuration was found to hold. It was found that the interaction energy between the $s$ electron and the nucleus as given by the Bacher-Goudsmit equations is not sufficient to account for the observed intervals but that the interaction energy between the $d$ electrons and the nucleus must also be considered.