Spectrum and energy levels of five-times ionized molybdenum, Mo VI

The Mo VI spectrum was photographed with a sliding spark discharge on the 10.7 m normal-incidence and grazing-incidence vacuum spectrographs at the National Institute of Standards and Technology. The observations covered the region 196-5300 A. The existing analysis of this spectrum due to Edlen et al (1985 Phys. Scr. 32 215) and Kancerevicius et al (1991 Lith. Phys. J. 31 143) was revised and extended. The ionization energy of Edlen et al, which had been called into question by Kancerevicius et al, was confirmed. There are now a total of 234 lines and 112 energy levels. From the optimized energy levels, Ritz-type wavelengths with uncertainties varying from 0.0003 to 0.0018 A were determined. The energy levels were theoretically interpreted by means of Hartee-Fock calculations and least-squares fits of the energy parameters to the observed levels. The fitted energy parameters were used to calculate oscillator strengths for all observed lines. By applying a polarization formula to the 6h-8h, 7i-8i, 8k levels, a revised value of the ionization energy of 555 127.5 ± 1.7 cm-1 (68.827 03 ± 0.000 21 eV) was determined.