The absolute cross section for photoionization of O₂(¹Δ_<i>g</i>)

Abstract

The absolute photoionization cross section for an electronically excited species, O2(1Δ g ), has been determined at λ=1067 å by comparison of rates of ion formation from nitric oxide and O2(1Δ g ) at known concentrations. Absolute cross sections in the wavelength range 1035 å to 1118 å have been calculated from relative cross section data which appear in the literature. The ionization cross section increases from about 2 × 10-18 cm2 to 6 × 10-18 cm2 between 1118 å and 1035 å, although there are some fluctuations over a smooth curve. These fluctuations are much less pronounced than those observed for photoionization of ground state O2, and a possible explanation for the difference is suggested.