The vacuum uv absorption spectrum of O2 from its metastable states b 1Σ+g and a 1Δg

Abstract

The absorption spectra of 16O2 and 18O2, excited by a transformer discharge, have been photographed with a 6.65 m vacuum spectrograph in the 1280–1620 Å region. The spectra were obtained in the first and second orders of a 1200 grooves/mm grating. New bands have been observed and assigned to the n=3 and 4 members of the Rydberg series npπu 1Σ+u←b 1Σ+g. The 4pπu 1Σ+u (v=1) level is overlapped and perturbed by a 1Πu state. Rotational analyses have been made for all the well resolved bands of 16O2 and 18O2. The vibrational quantum number assignments were based on the isotope shifts of 18O2 relative to 16O2. Rotational and vibrational constants for the upper states of the bands analyzed are reported and a discussion is given of these states in relation to the Rydberg states of O2 converging to the ground state of O+2. In addition, a new diffuse band at 1611.8 Å is discussed in terms of previously reported bands from the a 1Δg state.