The Nuclear Spin and Magnetic Moment of Sodium from Hyperfine Structure

The hyperfine structure of the sodium $D$ lines from a liquid-air cooled Schüler tube was observed with a Fabry-Perot interferometer. Each line has two resolvable components; the separations are: for $D_2\left(\lambda 5890\right)$, 0.0555 ${\mathrm{cm}}^{-1\mathrm{}}$, for $D_1\left(\lambda 5896\right)$, 0.0612 ${\mathrm{cm}}^{-1\mathrm{}}$. The total h.f.s. splitting for the $3{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ state is 0.0583 ${\mathrm{cm}}^{-1\mathrm{}}$, for the $3{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ state 0.0050 ${\mathrm{cm}}^{-1\mathrm{}}$ and for $3{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ 0.0083 ${\mathrm{cm}}^{-1\mathrm{}}$. Relative intensity measurements are consistent with a nuclear spin of $\frac{3}{2}$. The nuclear magnetic moment is calculated as $\frac{2.7}{1840}$ Bohr magnetons.