Analysis of the First Short Period and Its Isoelectronic Sequences

The configurations 2pⁿ, 2s2p^n-1, and 2s²2p^n-2 are analyzed for all observed spectra of the respective isoelectronic sequences. The semiempirical Slater method is amended to include the polarization correction and, wherever possible, configuration interaction. The polarization parameter Λ is found to be approximately linear in the degree of ionization, q. The Slater parameters characteristic of the term separations of 2sᵐ2pⁿ and of configuration interaction are found to be linear functions of m, n, and q, partly corresponding to the Bacher-Goudsmit theory in second approximation. A comparison with self-consistent field calculations is made. Other consequences of the analysis are discussed.