Rydberg Absorption Series and Ionization Energies of the Oxygen Molecule. I

Rydberg absorption series of O₂ have been investigated with a 6.6‐m normal‐incidence vacuum spectrograph in the first and second orders in the 600–750‐Å region. Previous observations have been improved upon, and it has been possible to obtain much more accurate ionization energies for the $b^4{\Sigma }_g^{-}$ and $B^2{\Sigma }_g^{-}$ states of O₂⁺. The data are compared with recent results obtained in the investigation of the electron energy spectrum of photoionized O₂⁺. Another Rydberg series converging to the $B^2{\Sigma }_g^{-}$ state has been observed and is now reported for the first time.