The spectrum of selenium has been observed in the wavelength region 1200–100 Å on the 10.7 m normal incidence and 10.7 m grazing incidence vacuum spectrographs at the NBS Laboratory in Washington. A triggered vacuum spark was used as a source. The “pole effect” exhibited by the lines on the normal incidence spectrograms helped to discriminate different stages of ionization of the selenium spectra. All the levels belonging to the 3d<sup>9</sup>4s and 3d<sup>9</sup>4p configurations in Se VII have been located. The parametric level fitting calculations of the energy levels agree with the experimental values. In Se VIII, the 3p<sup>5</sup>3d<sup>10</sup><sup>2</sup>P° term has been determined.
© 1977 Optical Society of AmericaPDF Article