Hyperfine Structure and Nuclear Moments of Gadolinium

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 $\frac{{\mu }_I\left({\mathrm{Gd}}^{155}\right)}{{\mu }_I\left({\mathrm{Gd}}^{157}\right)}=0.80\mathrm{}\pm 0.02$. The magnetic moment for ${\mathrm{Gd}}^{157}$ obtained from two lines is -0.37±0.04 nm. Deviations from the interval rule in these two lines can be accounted for with a quadrupole moment of approximately 1.0×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ for ${\mathrm{Gd}}^{157}$ and 1.1×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ 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.