Spark spectra of thallium and lead

The atomic spectra of Thallium were excited and photographed in the spectral region from 340 to 9000 Å , using both an electrodeless discharge and a spark-in-Helium as light sources. The single electron Rydberg series have been extended in TI III. The ionization potential of TI III and Pb IV was determined from hydrogenic terms and found to be 240773 ± 5 cm⁻¹ and 342438 ± 5 cm⁻¹ respectively. The dipole polarizability of TI III was found to be 2.53 ± .02 a³₀ and of Pb IV 4.37 ± .04 a³₀. Using a line list previously obtained in this laboratory, terms belonging to three electron configuration were established in TI III and Pb IV. The 5d⁹ ns series was extended in TI IV and an ionization potential of 412500 ± 300 cm⁻¹ arrived at. In TI IV and Pb V the two electron configurations 5d⁹ 6d, 5d⁹ 5f, 5d⁹ 7p and 5d⁸ 6s² were partially established while a number of terms belonging to the complex 5d⁸ 6s6p configuration could be identified as well. The analysis of TI II was extended by completing the 5d¹º 6p² configuration and identifying a number of odd and even parity terms above the first ionization limit. These were tentatively assigned to the 5d¹º 6p7p, 5d⁹ 6s² 7s, 5d⁹ 6s² 6d, 5d⁹6s6p² and the 5d¹º6p7s configurations. The number of classified TI III lines, involved in this extension of the term analysis, has increased from 247 to 579. In the TI IV spectrum the increase in classified lines has been from 35 to 308 lines. In lead spectra the increase in Pb IV has been from 134 lines to 460, and in Pb V the corresponding increase is from 200 to 303 lines.Science, Faculty ofPhysics and Astronomy, Department ofGraduat