The Coupling ofpElectron Configurations

The structure and type of coupling of the observed $p^2$, $p^3$, and $p^4$ configurations is considered in detail in terms of the intermediate-coupling theory, in particular for the long isoelectronic sequences which have recently been analyzed. The theoretical values of the ratios of various intervals in these configurations are plotted as functions of the single parameter which specifies the type of coupling. The experimental values have been fitted to these curves and the parameters evaluated. The points fit the theoretical curves fairly well; and the departures of the experimental points of an isoelectronic sequence from these curves are sufficiently regular to enable accurate prediction of unknown levels. This method has yielded new classifications in K IV and Ca VII. For the configurations $p^3$ and $p^{3}s$, interval ratios are found which are predicted to be entirely independent of coupling. The parameters are plotted for the isoelectronic sequences of $\mathrm{sp}$, $p$, $p^2$, $p^3$, $p^4$, $p^5$, and $p^{5}s$ configurations. The electrostatic interaction parameter $F_2$ is found to be a linear function of $Z$ to a good approximation; the spin-orbit parameter ${\zeta }_p$ is accurately proportional to ${\mathrm{}(Z-S)\mathrm{}}^4$ for all but the first few members of each sequence. The screening constants ($S$) for ${\zeta }_p$ are much smaller than the corresponding screening constants for $F_2$. A complete bibliography of data for those atoms with $p$ electrons in the normal configuration is appended.