Asymmetric autoionized lines have been observed for the first time in an atomic emission spectrum. Several members of the 2s22p23P–2s2p2(4P)np3D° Rydberg series have been observed which interact with the 2S22p(2P°)np3D° continuum beyond the first ionization limit, 2s22p2P½°, in the triplet levels of O III. Symmetric autoionized lines of the 2s22p23P–2s 2p2(4P)np3P° Rydberg series have also been observed in this same spectrum.
S. G. TILFORD and P. G. WILKINSON, "Asymmetric Autoionized Lines in the Emission Spectrum of O III," J. Opt. Soc. Am. 54, 322-324 (1964)