Preliminary Level Analysis of the First and Second Spectra of Dysprosium, Dy i and Dy ii*

Accurate wavelengths and wavenumbers of over 22 000 dysprosium lines have been measured in the wavelength region 2300–11 400 Å. The Zeeman effect has been observed at a field strength of 24 000 G from 2300 to 9000 Å. By comparison of relative intensities of the lines from sources under various conditions, 85% of the lines have been assigned as Dy i or Dy ii spectrum lines. From the energy-level analysis, 141 even and 197 odd levels of Dy i are known. Combinations between these levels account for 1952 lines. For Dy ii, 14 even and 214 odd levels are known, with 1000 lines classified. The ground levels of Dy i and Dy ii are 4f¹⁰6s^{2 5}I₈ and $4f^{10}6s⁶I_{8\frac{1}{2}}$, respectively. The lowest level of the 4f⁹5d6s² configuration of Dy i lies 7565.62 cm⁻¹ above the ground level. The g values for most of the levels of both spectra are given.