Hyperfine Structure and Nuclear Moments of Gadolinium

Abstract

Study of the optical hyperfine structure of several Gd i lines using enriched isotopes shows that the spins of the odd isotopes ${\mathrm{Gd}}^{155}$ and ${\mathrm{Gd}}^{157}$ each are $\frac{3}{2}$. The ratio of the magnetic moments is $\frac{{\ensuremath{\mu}}_{I}({\mathrm{Gd}}^{155})}{{\ensuremath{\mu}}_{I}({\mathrm{Gd}}^{157})}=0.80\ifmmode\pm\else\textpm\fi{}0.02$. The magnetic moment for ${\mathrm{Gd}}^{157}$ obtained from two lines is -0.37\ifmmode\pm\else\textpm\fi{}0.04 nm. Deviations from the interval rule in these two lines can be accounted for with a quadrupole moment of approximately 1.0\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$ for ${\mathrm{Gd}}^{157}$ and 1.1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$ for ${\mathrm{Gd}}^{155}$. The known anomolous isotope shift between neutron numbers 88 and 90 (${\mathrm{Gd}}^{152}$ and ${\mathrm{Gd}}^{154}$) is accurately measured for several lines.