The sixth spectrum of iridium (Ir VI): Determination of the 5d(4), 5d(3)6sand 5d(3)6p configurations

The spectrum of five times ionized iridium, Ir VI, was investigated in the 420-1520 Angstrom wavelength region. The analysis has led to the determinat ion of the 5d(4), 5d(3)6s and 5d(3)6p configurations. Thirty of thirty four theoretically possible 5d(4) levels, 27 of 38 possible 5d(3)6s levels and 96 of 110 possible 5d(3)6p levels have been established. The levels are bas ed on 711 classified spectral lines. The level structure of the configurati ons has been theoretically interpreted using the orthogonal operators techn ique. The energy parameters have been determined by a least squares fit to the observed levels. Calculated energy values and LS-compositions, obtained from the fitted parameter values are given.