Hyperfine structure study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Tc</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>97</mml:mn><mml:mo>,</mml:mo><mml:mn>98</mml:mn><mml:mo>,</mml:mo><mml:mn>99</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> in a new laser ion source for high-resolution laser spectroscopy
Tomas Kron, R. Beerwerth, S. Raeder, S. Fritzsche, Reinhard Heinke, Pascal Schönberg, M. Trümper, K. Wendt
Abstract
Using a novel concept for efficient laser spectroscopy, we investigated the hyperfine splittings of three different atomic transitions in the long-lived isotopes $^{97\ensuremath{-}99}\mathrm{Tc}$. 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 $^{97,98}\mathrm{Tc}$ from which, in combination with the known nuclear moments of $^{99}\mathrm{Tc}$, their nuclear magnetic dipole and electric quadrupole moments were extracted. In addition, the experimental data confirm the predicted nuclear spin of $^{98}\mathrm{Tc}$ 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.