Spectrum and Energy Levels of Five-Times Ionized Zirconium (Zr VI)

We carried out a new analysis of the spectrum of five-times-ionized zirconium Zr VI. For this we used sliding-spark discharges together with normal- and grazing-incidence spectrographs to observe the spectrum from 160 to 2000 Å. These observations showed that the analysis of this spectrum by Khan Z. A. et al. 1985 Phys. Scr.31 837 contained a significant number of incorrect energy levels. We have now classified ∼420 lines as transitions between 23 even-parity levels 73 odd-parity levels. The 4s²4p⁵, 4s4p⁶, 4s²4p⁴4d, 5s, 5d, 6s configurations are now complete, although a few levels of 4s²4p⁴5d are tentative. We determined Ritz-type wavelengths for ∼135 lines from the optimized energy levels. The uncertainties range from 0.0003 to 0.0020 Å. Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels were used to interpret the observed configurations. 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 777380±300 cm^-1 (96.38±0.04 eV).