Abstract
A further investigation of the perturbation by excited core states of gyromagnetic ratios for atoms consisting of a single electron outside closed shells takes account of the spin orbit interaction of the excited core. Although the effect vanishes to lower orders than the fourth, and at least the first term in the expansion of the electrostatic interconfiguration interaction cancels even in that order, there is for alkali atoms a residual correction possibly large enough to account for observed deviations of g values from those expected. Calculations have also been made for P2 states: The effect in gallium is negligible, but the anomalous observed gJ(P32)gJ(P12) for indium may be at least in part due to perturbations of this kind.