W. Whaling et al., ARGON ION LINELIST AND LEVEL ENERGIES IN THE HOLLOW-CATHODE DISCHARGE, Journal of quantitative spectroscopy & radiative transfer, 53(1), 1995, pp. 1-22
Lines of Ar I, II, and III are identified in high-resolution Fourier T
ransform spectra of a hollow-cathode source covering the range 222-586
5 nm. Ar II and III level energies are extracted and compared with ear
lier measurements. Selected Ar II lines suitable for use as secondary
wavelength standards are measured relative to precise wavelengths of C
O molecular lines.