Hyperfine structure study of Tc-97,Tc-98,Tc-99 in a new laser ion source for high-resolution laser spectroscopy

Using a novel concept for efficient laser spectroscopy, we investigated the hyperfine splittings of three different atomic transitions in the long-lived isotopes Tc97-99. Despite the refractory character of the element technetium, sample sizes as low as 10(11) atoms were sufficient to achieve excellent signal-to-noise ratios at a spectroscopic linewidth of less than 100 MHz. The obtained spectra were analyzed in detail, which results in a very good consistency for the extracted hyperfine parameters from the different transitions. The presented measurements provide the first hyperfine structure data for the isotopes Tc-97,Tc-98 from which, in combination with the known nuclear moments of Tc-99, their nuclear magnetic dipole and electric quadrupole moments were extracted. In addition, the experimental data confirm the predicted nuclear spin of Tc-98 to I = 6. In combination with atomic Multiconfiguration Dirac-Hartree-Fock calculations, the observed isotope shifts were investigated and the changes in mean-square charge radii were determined.