ANALYSES OF THE 5D(2)-5D7P TRANSITIONS IN THE TA-IV AND W-V SPECTRA

The spectra of tantalum and tungsten were photographed on a 3 m normal incidence spectrograph using a sliding spark and a triggered spark li ght source. The 5d(2)-5d7p transitions in the Ta IV and W V were inves tigated. All 12 levels of the 5d7p configuration in both Ta IV and W V have been established. The 5d7p and 5d5f configuration interaction ha s helped us to identify three of the four missing levels of the 5d5f c onfiguration in Ta IV and one missing level in W V. Sixty-six lines in Ta IV and 45 lines in W V have been additionally classified. Parametr ic calculations interpret the observed spectra satisfactorily. Ionizat ion potentials of Ta IV and W V have been estimated to be Ta V D-2(3/2 ) = 294 700 +/- 1500 cm(-1) (36.53 +/- 0.18 eV) and W VI D-2(3/2) = 42 1 300 +/- 800 cm(-1) (52.22 +/- 0.10 eV), respectively.