Certain Multiplets in the Spectra of Cadmium III and Indium IV

Terms and related wave-lengths and frequencies arising from the configuration d¹⁰, d⁹s, d⁹p of Cd III and In IV.---Guided by the transitions from ³PDF, ¹PDF, (4d⁹5p) to ³D, ¹D (4d⁹5s) already determined for Pd I and Ag II the corresponding lines have been identified in the spectra of Cd III and In IV. The transitions from ³D₁, ³P₁ and ¹P₁(4d⁹5p) to ¹S₀(4d¹⁰) the latter being the lowest level in each of these spectra, have also been identified for Ag II, Cd III and In IV. These combinations account for nearly all of the strong lines in each spectrum. The term values for the four iso-electronic systems Pd I, Ag II, Cd III, and In IV, together with those for the corresponding elements in the first long period have been plotted on a Moseley diagram which brings out certain similarities and variations between these two sets of spectra. The validity of the irregular doublet law is again confirmed by the almost constant shift in the corresponding radiated frequencies (4d⁹5s-4d⁹5p) on passing in succession from Pd I to Ag II, to Cd III, and to In IV.