Hyperfine Structure ofI8,75Atomic States ofDy161,163and the Ground-State Nuclear Moments

The atomic-beam magnetic-resonance technique has been used to measure the hyperfine structure of the $4f^{10}6s^2{}_{}{}^5{}_{}{}^{}I_{8,7}^{}{}_{}{}^{}$ atomic states of ${\mathrm{Dy}}^{161,163}$. Values of the hyperfine-interaction constants $A$, $B$, and $C$, corrected for hyperfine interactions with other states, are given for both atomic states of each isotope. It is found that for the nuclear ground states of ${\mathrm{Dy}}^{161,163}$, $\frac{{\mu }^{163}}{{\mu }^{161}}=-1.400\mathrm{}\left(3\right)\mathrm{}$, and, less accurately, ${\mu }^{163}=+0.65\mathrm{}\left(6\right)\mathrm{}{\mu }_N$, $Q^{163}=+2.51\mathrm{}\left(30\right)\mathrm{} \mathrm{b}$, ${\mu }^{161}=-0.46\mathrm{}\left(5\right)\mathrm{}{\mu }_N$, $Q^{161}=+2.37\mathrm{}\left(28\right)\mathrm{} \mathrm{b}$. The electron $g$ factor $g_J$ is measured for the atomic states $4f^{10}6s^2{}_{}{}^5{}_{}{}^{}I_{8,7,6}^{}{}_{}{}^{}$ and also for the lowest $J=8\mathrm{}$ level of $4f^{9}5d6s^2$ at 7565 ${\mathrm{cm}}^{-1\mathrm{}}$. The lifetime of this level cannot be appreciably less than 2 msec, the transit time for the atom in the apparatus.