Zeeman Effect in theP122Level of Atomic Fluorine

The position of the $(F, M_F)=(1, 0)\leftrightarrow (1, -1)$ transition in the ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ level of atomic fluorine has been accurately measured and a $g$ factor calculated. The result is $g_J(F; {}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{})=0.665\mathrm{}6117\pm 0.0000021$. This result is in excellent agreement with the previously published value of 0.665 61 ± 0.000 03, but differs by 25 parts per million from a recent calculation carried out to order ${\alpha }^2$ in relativistic contributions according to the theory of Kambe and Van Vleck. The result is discussed in terms of the theories of Abragam and Van Vleck, and Kambe and Van Vleck.