Seventh spectrum of tungsten (W vii); resonance lines of Hf v

Observations of W vii were carried out in the spectral range 100 to 2000 {} utilizing normal- and grazing-incidence spectrographs. The light source was a sliding spark operated at peak currents of 1000 to 3000 A. Eighty-five energy levels of 4f¹³nl and 5p⁵nl configurations were deduced for nl=5d, 6s, 6p, 6d, and 7s. These are based on the classification of 310 lines in the range 130 to 1436 {}. Calculations of all observed configurations were carried out with configuration interaction (CI) for the purpose of fitting radial integrals and confirming the analysis. The strong CI between p⁵nl and f¹³nl configurations where $nl=5d, 6p, 6d$ provided well-defined CI integrals in good agreement with Hartree-Fock values. A value of 984 100 ±{} 500 cm^-1 was derived for the ionization energy from the 4f¹³ns series. The resonance lines of Hf v for 5p⁶-5p⁵5d, $6s$ are given. A revised value for the the ionization energy of W vi is given.