Quadrupole Moments ofTa181andLu175

Abstract

The hyperfine structure of the spectrum of Ta i was studied by means of a hollow-cathode discharge tube and a Fabry-P\'erot \'etalon, in order to determine the quadrupole moment of ${\mathrm{Ta}}^{181}$. The calculation was carried out for the quadrupole coupling constants of the levels $^{4}F_{\frac{3}{2}}$, $^{4}P_{\frac{3}{2}}$, $^{4}F_{\frac{5}{2}}$, $^{4}F_{\frac{7}{2}}$ and $^{4}F_{\frac{9}{2}}$ of the configuration $5{d}^{3}6{s}^{2}$, in which the three $5d$-electrons are combined by an intermediate coupling. This yielded the result that $Q({\mathrm{Ta}}^{181})=(+4.3\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$, in which the polarization correction (due to Sternheimer) is taken into account. The value of $Q({\mathrm{Lu}}^{175})$ was calculated from the data given in the literature, and was found to be (+5.7\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$.