Precision Measurement of the ElectronicgFactors of the Alkali Metals

Abstract

We have measured the ratios of the electronic $g$ factors of ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$, ${}_{}{}^{85,87}{}_{}{}^{}\mathrm{Rb}$, and ${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$ to that of ${}_{}{}^{39}{}_{}{}^{}\mathrm{K}$, using the atomic-beam magnetic-resonance technique. The results are $\frac{g_J\left({}_{}{}^{23}{}_{}{}^{}\mathrm{Na}\right)}{g_J\left({}_{}{}^{39}{}_{}{}^{}\mathrm{K}\right)}=1.0000007\mathrm{}\mathrm{}\left(2\right)\mathrm{}$, $\frac{g_J\left({}_{}{}^{85,87}{}_{}{}^{}\mathrm{Rb}\right)}{g_J\left({}_{}{}^{39}{}_{}{}^{}\mathrm{K}\right)}=1.0000182\mathrm{}\mathrm{}\left(2\right)\mathrm{}$, and $\frac{g_J\left({}_{}{}^{1333}{}_{}{}^{}\mathrm{Cs}\right)}{g_J\left({}_{}{}^{39}{}_{}{}^{}\mathrm{K}\right)}=1.0001231\mathrm{}\mathrm{}\left(3\right)\mathrm{}$. These results, combined with the results of other researchers, yield the following absolute $g$ factors for the alkali metals: $g_J\left(\mathrm{Na}\right)=-2.002297\mathrm{}\mathrm{}\left(2\right)\mathrm{}$, $g_J\left(\mathrm{K}\right)=-2.002295\mathrm{}\mathrm{}\left(2\right)\mathrm{}$, $g_J\left(\mathrm{Rb}\right)=-2.002332\mathrm{}\mathrm{}\left(2\right)\mathrm{}$, and $g_J\left(\mathrm{Cs}\right)=-2.002542\mathrm{}\mathrm{}\left(2\right)\mathrm{}$. These $g$ factors, with the exception of the value for Cs, are in good agreement with theoretical values.