Spectrum and Energy Levels of Four-Times Ionized Yttrium (Y V)

The analysis of the spectrum of four-times-ionized yttrium, Y V, was extended to provide a large number of new spectrum lines and energy levels. The new analysis is based on spectrograms made with sliding-spark discharges on 10.7 m normal- and grazing-incidence spectrographs. The measurements cover the region 184-2549 angstrom. The results revise levels for this spectrum by Zahid-Ali et al. (1975) and by Ateqad et al. (1984). Five hundred and seventy lines were classified as transitions between 23 odd-parity and 90 even-parity levels. The 4s(2)4p(5), 4s4p(6), 4s(2)4p(4)4d, 5s, 5p, 5d, 6s configurations are now complete. Results for the 4s(2)4p(4)6d and 7s configurations are tentative. Ritz-type wavelengths were determined from the optimized energy levels, with uncertainties as low as +/- 0.0004 angstrom. The observed configurations were interpreted with Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels. Oscillator strengths for all classified lines were calculated with the fitted parameters. The results are compared with values for the level energies, percentage compositions, and transition probabilities from recent ab initio theoretical calculations. The ionization energy was revised to 607,760 +/- 300 cm(-1) (75.353 +/- 0.037 eV).