The Theory of Complex Spectra II

Formulas for the relations between the energies of multiplets arising from the same electron configuration for all two-electron cofigurations up to ff and several cases of three-electron configurations are worked out following Slater’s method; Slater’s table of a’s and b’s being extended to cover f electrons. A systematic comparison of the known data with this first order perturbation theory shows poor agreement in many cases and good agreement in many. The theory predicts the observed alternation in the relative positions of singlet and triplet through S, P, D, F, etc. in the pp, pd, and pf triads, and the dd and df pentads. In general the p electron configurations fit very poorly; a uniform trend with atomic number is observed for p 3 and good fits are obtained for 4p3d in Ti III, V IV, and Cr V. For d electrons the theory fits very well in the first long period of the periodic table, and fairly well in the second. The 1 S of d 2 and the 2 D of d 2 s are predicted much higher than the levels assigned to those multiplets when such an assignment is made, d 3 fits well except for 2 P. An energy level table of La II is given as recently analysed by Meggers and Russell. Here we have complete 5d4f and 4f 2 configurations which fit the theory very well, these calculations having assisted in the assignment of some of the singlets and resulted in a rearrangement of singlet lines.