Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers

Collinear laser spectroscopy experiments with the Sc+ transition 3d4s D-3(2) -> 3d4p F-3(3) at lambda = 363.1 nm were performed on the Sc42-46 isotopic chain using an ion guide isotope separator with a cooler-buncher. Nuclear magnetic dipole and electric quadrupole moments as well as isotope shifts were determined from the hyperfine structure for five ground states and two isomers. Extensive multi-configurational Dirac-Fock calculations were performed in order to evaluate the specific mass-shift, M-SMS, and field-shift, F, parameters which allowed evaluation of the charge radii trend of the Sc isotopic sequence. The charge radii obtained show systematics more like the Ti radii, which increase towards the neutron shell closure N = 20, than the symmetric parabolic curve for Ca. The changes in mean-square charge radii of the isomeric states relative to the ground states for Sc-44 and Sc-45 were also extracted. The charge radii difference between the ground and isomeric states of Sc-45 is in agreement with the deformation effect estimated from the B(E2) measurements but is smaller than the deformation extracted from the spectroscopic quadrupole moments.