Hyperfine structure of the 5dDJ2states in the alkaline-earth Ba ion by fast-ion-beam laser-rf spectroscopy

The hyperfine structure (hfs) of the 5d ${\mathrm{}}^2$ $D_{5/2}$ ${}_{}{}^{135}{}_{}{}^{}$,137Ba ions has been measured by collinear fast-beam laser-rf double-resonance spectroscopy, completing the high-precision hfs data for the metastable ${}_{}{}^2{}_{}{}^{}\mathrm{D}_{3/2}^{}{}_{}{}^{}$,5/2 doublet. hfs constants, corrected for second-order hfs perturbation, are deduced and compared with the results of many-body perturbation theory. Nuclear quadrupole moments are extracted.