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 Gd¹⁵⁵ and Gd¹⁵⁷ each are 3/2. The ratio of the magnetic moments is μI(Gd¹⁵⁵)μI(Gd¹⁵⁷)=0.80±0.02. The magnetic moment for Gd¹⁵⁷ 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 cm² for Gd¹⁵⁷ and 1.1×{}10^-24 cm² for Gd¹⁵⁵. The known anomolous isotope shift between neutron numbers 88 and 90 (Gd¹⁵² and Gd¹⁵⁴) is accurately measured for several lines.