Energy levels in Ar ii

The spectra of Cu, Mg, and V, produced by a hollow cathode with Ar and Ne as carrier gases, have been registered in the infrared region (1800–9000 ${\mathrm{cm}}^{\mathrm{-}1}$) with the Fourier-transform spectrometer at the National Solar Observatory on Kitt Peak. These spectra reveal the presence of three groups of lines around 1.8, 3.1, and 2.9 μm. Many of these emission lines have been identified as 3${\mathit{p}}^4$ ${(}^3$P)5f-6g, 5g-6h, 6g-7h, 6h-7i, and 6f-7g transitions in Ar i i. From these observations, it has been possible to extend the term system of this ion and to determine the energies of approximately 70 new levels. More precisely, the 3${\mathit{p}}^4$ ${(}^3$P)6h, 7h, and 7i configurations have been analyzed.