Spectrum and energy levels of quadruply-ionized molybdenum (Mo V)

Abstract

The spectrum of quadruply-ionized molybdenum Mo V was observed from 200 to 4700 Å with sliding spark discharges on 10.7 m normal- and grazing-incidence spectrographs. The existing analyses of this spectrum (Tauheed et al 1985 Phys. Scr. 31 369; Cabeza et al 1986 Phys. Scr. 34 223) were extended to include the 5s2, 5p2, 5s5d, 5s6s, 4d5f, and 4d5g configurations as well as the missing 3H6 level of 4d4f and about 75 levels of the core-excited configuration 4p54d3. The values of the 4d5d 1S0, 5s5p 1P1, and 4d6p 3P0 levels were revised. There are now about 900 lines classified as transitions between 66 even parity and 191 odd parity energy levels. Of these, about 600 lines and 130 levels are new. From the optimized energy level values, Ritz-type wavelengths were determined for about 380 lines, with uncertainties varying from 0.0003 to 0.002 Å. The observed configurations were theoretically interpreted by means of Hartree–Fock calculations and least-squares fits of the energy parameters to the observed levels. The fitted parameters were used to calculate oscillator strengths for all classified lines. A few unclassified lines and undesignated levels are also given. An improved value for the ionization energy was obtained by combining the observed energy of the 4d5g configuration with an ab initio calculation of its term value. The adopted value is 438 900 ± 150 cm−1 (54.417 ± 0.019 eV).

Stellar laboratories

“…Oscillator strengths were published by Reader & Tauheed (2015) for 923 lines of Mo v and by Reader (2010) Fig. 12) and were used for the abundance determination, the log g f -values are almost identical.…”

“…In this ion, the semi-empirical process was performed to optimize the radial integrals corresponding to 4d 2 , 4d5s, 4d6s, 4d5d, 4d5g, 5s 2 , 5p 2 , 5s5d, 5s6s, 4d5p, 4d6p, 4d4f, 4d5f, 4d6f, 4d7f, 4d8f, 4d9f, 5s5p, 5s4f, and 4p 5 4d 3 configurations, which use the experimental energy levels reported by Reader & Tauheed (2015). Core-polarization effects were estimated using a dipole polarizability value corresponding to a Mo viii ionic core taken from Fraga et al (1976), i.e., α d = 1.48 au, and a cut-off radius equal to 1.20 au.…”

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

“…The analysis was carried out in a manner similar to that used for the recent analysis of Mo V [11]. As described there "Interpretation of the spectrum was guided by calculations of the level structures and transition probabilities with the Hartree-Fock code of Cowan [12].…”

“…The shorthand designations are explained in the footnotes to Tables 2 and 3. As described in [11] "The values of the energy levels were optimized with the computer program ELCALC, an iterative procedure in which the observed wave numbers are weighted according to the inverse square of their uncertainties. The uncertainties of the level values given by this procedure are also listed."…”

“…As in [11] "The observed configurations were interpreted theoretically by making least-squares fits of the energy parameters to the observed levels with the Cowan suite of codes, RCN (Hartree-Fock), RCG (energy matrix diagonalization), and RCE (least-squares parameter fitting) [12]. The Hartree-Fock code was run in a relativistic mode (HFR) with a correlation term in the potential.…”