Experimental and theoretical study of the hyperfine structure in the lower configurations in 45Sc II.

Abstract

We have measured the hyperfine structure (hfs) of 12 levels in the configurations 3d4s, 3${\mathit{d}}^{2}$, and 3d4p in singly ionized scandium by collinear fast-ion-beam--laser spectroscopy. The hfs of the four levels in the configuration 3d4s has to our knowledge not been measured before. From these levels the ions were excited to levels in the 3d4p configuration by the frequency-doubled output of a ring dye laser with an intracavity mounted ${\mathrm{LiIO}}_{3}$ crystal. Levels in the 3${\mathit{d}}^{2}$ configuration were excited to levels in the 3d4p configuration with visible laser light. The resulting magnetic dipole (A) and electric quadrupole (B) hfs constants are analyzed in Sandars-Beck effective-operator formalism. The multiconfiguration Dirac-Fock method has been used to calculate the hfs constants for levels in the configurations 3d4s, 3d5s, 3d6s, 3${\mathit{d}}^{2}$, and 3d4p. Within the framework of the configuration-interaction method, an approach is presented for the calculation of the core polarization, which uses a virtual basis set localized inside the core. For all levels, this approach gives better results compared to previously published calculations.