Nuclear Moments of ${\mathrm{Nb}}^{93}$, ${\mathrm{La}}^{139}$, ${\mathrm{Os}}^{187}$, and ${\mathrm{Hg}}^{201}$

The effective charge $Z^{*}$ for a $d$-electron was studied by means of a hyperfine structure (hfs) investigation; the screening correction ($Z-Z^{*}$) was found to range from 15 to about 19 for the charge number $Z$ ranging from 27 to 78. Investigation of the hfs of the spectra of Nb i and La i yielded the result that $Q\left({\mathrm{Nb}}^{93}\right)=(-0.2\mathrm{}\pm 0.1)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ and $Q\left({\mathrm{La}}^{139}\right)=(+0.6\mathrm{}\pm 0.2)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$, respectively, in which the polarization correction (due to Sternheimer) is taken into account. In the hfs of the spectrum of Os i the components due to the rarer odd isotope ${\mathrm{Os}}^{187}$ were detected and it was found that ${\mathrm{Os}}^{187}$ has a spin ½ and a magnetic moment most probably equal to +0.12 nm (possible range being from +0.16 nm to +0.09 nm). The quadrupole moment of ${\mathrm{Hg}}^{201}$ was calculated from the hfs of $6s6p{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ and $6s6p{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ of the spectrum of Hg i, taking the configuration interaction into account, and $Q\left({\mathrm{Hg}}^{201}\right)=(+0.45\mathrm{}\pm 0.04)\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ was obtained.