The atomic spectra of thallium were excited and photographed in the spectral region between 340 and 9000 Å using as light sources both an electrodeless discharge and a spark-in-helium.The line list of lead previously obtained in this laboratory was supplemented, in the 340 to 1000 Å region, using a spark-in-helium light source to provide excitation data.The 5d10nl series, l = 0 to l = 5, have been extended in Tl III, while the 5d10 6f and 5d10 7f terms have been found in Pb IV. Minor adjustments and additions have been made in the 5d9 6s6p configuration of Tl III and Pb IV. The 5d9 6s7s configuration was established in Tl III and Pb IV. The [Formula: see text], [Formula: see text] energy levels belonging to the 5d9 6s6d configuration have been found in Tl III and Pb IV. Energy levels in Tl III and Pb IV, with [Formula: see text], [Formula: see text], [Formula: see text], have been assigned to the 5d9 6p2 configuration, and a number of levels belonging to the 5d9 6s7p configuration in Tl III have been established. The number of classified lines in Tl III is 495, while in Pb IV, 367 lines now appear in the classified line list. The 5d101S0 ionizational potentials of Tl III and Pb IV are respectively 240 773 ± 5 cm−1 and 341 438 ± 5 cm−1.
Selected tables of atomic spectra - A atomic energy levels-second edition, B multiplet tables :