ANALYSIS OF THE (5D(9)+5D(8)6S)-[5D(8)(5F+6F+7P)+5D(7)6S6P] TRANSITIONS OF QUADRUPLY IONIZED THALLIUM (TL-V)

The spectrum of thallium was photographed in the 200-625 Angstrom region on 6.65 m and 10.7 m grazing incidence spectrographs using sliding spark and triggered spark sources. The (5d(9) + 5d(8)6s)-5d(8)(5f + 6f + 7p)+ 5d(7)(6s6p) transition array of T1 V were analysed. 710 lines have been classified in these arrays. 285 levels out of a total of 429 levels belonging to these four odd configurations have been established. The highest J = 0.5 level belonging to the 5d(8)6s configuration and the highest J = 1.5 level of the 5d(8)6p configuration, previously unknown, have also been located. Parametric least-square fitting calculations involving configuration interactions were carried out to interpret the observed spectrum. The ionization potential of T1 V has been estimated to be 505 000 +/- 3000 cm(-1) (62.6 +/- 0.4 eV).