Hyperfine Structure of Praseodymium-142

The hyperfine structure of 19-hr ${\mathrm{Pr}}^{142}$ in the electronic ground state ${}_{}{}^4{}_{}{}^{}I_{\frac{9}{2}}^{}{}_{}{}^{}$ has been studied by the atomic-beam magnetic-resonance method. The following results have been obtained: electronic splitting factor $g_J\left({}_{}{}^4{}_{}{}^{}I_{\frac{9}{2}}^{}{}_{}{}^{}\right)=-0.7322\mathrm{}\left(3\right)\mathrm{}$, nuclear spin $I=2\mathrm{}$, magnetic-dipole hyperfine-structure constant $\mathrm{}\left|A\right|=67.5\mathrm{}\left(5\right)\mathrm{}$ Mc/sec, electric-quadrupole hyperfine-structure constant $\mathrm{}\left|B\right|=7.0\mathrm{}\left(2.0\right)\mathrm{}$ Mc/sec, and $\frac{B}{A}>0\mathrm{}$. From the hyperfine-structure constants, and assumptions made concerning the electronic fields at the nucleus, the nuclear moments are calculated to be $\left|{\mu }_I\mathrm{}\right|=0.297\left(15\mathrm{}\right)\mathrm{}$ nm, and $\mathrm{}\left|Q\right|=0.035\mathrm{}\left(15\right)\mathrm{}$ b, with $\frac{Q}{{\mu }_I}>0\mathrm{}$.