The spectrum of Nb xiii was observed with a low-inductance spark and a laser-produced plasma in the region from 70–630 Å on the 10.7-m grazing incidence spectrograph at NBS. From the identification of 38 lines, a system of 29 energy levels was determined. The level system (Cu i isoelectronic sequence, 3d 10nl) includes the series ns(n = 4–6), np(n = 4–7), nd(n = 4–6), nf(n = 4–7), and ng(n = 5–8). The observed energy levels are compared with Hartree-Fock calculations. The ionization energy is determined from the nf and ng series to be 2 166 300 ± 300 cm −1 (268.59 ± 0.04 eV).
© 1980 Optical Society of AmericaFull Article | PDF Article