Radiative association and inverse predissociation of oxygen atoms

The formation of $O_2$ by radiative association and by inverse predissociation of ground state oxygen atoms is studied using quantum-mechanical methods. Cross sections, emission spectra, and rate coefficients are presented and compared with prior experimental and theoretical results. At temperatures below 1000~K radiative association occurs by approach along the $1{}^3{\mathrm{\Pi }}_u$ state of $O_2$ and above 1000~K inverse predissociation through the $B{}^3{\mathrm{\Sigma }}_u^{-}$ state is the dominant mechanism. This conclusion is supported by a quantitative comparison between the calculations and data obtained from hot oxygen plasma spectroscopy.