ANALYSIS OF THE 5D5F CONFIGURATION OF TREBLY IONIZED-TANTALUM AND QUADRUPLY IONIZED TUNGSTEN - TA-IV AND W-V

The spectra of trebly ionized tantalum and quadruply ionized tungsten were photographed in the 300 Angstrom-1220 Angstrom region on a 3-m no rmal incidence spectrograph at the Antigonish laboratory using a trigg ered spark and a sliding spark source. The earlier analyses of the (5d (2) + 5d6s)-(5d6p + 6s6p) transitions have been confirmed. The analyse s of the 5d(2)-5d5f transitions of Ta IV and W V have resulted in clas sifying 49 lines in each of these spectra. Out of the 20 possible leve ls of the 5d5f configuration 16 levels in Ta IV and 17 levels in W V h ave been established. The least-squares-fitting (LSF) and Hartree-Fock (HF) configuration interaction calculations were carried out and they interpret both spectra satisfactorily. The energy parameters and the scaling factors have been compared in the isoelectronic sequence from Ta IV to Ir VIII and they show smooth variations.