About possible origin of continual emission bands recorded in spectra of a plasma containing heavy inert gases doped with sulfur trioxide

Spectral continua with peaks of intensity near 350 and 248 nm, found in the radiation of plasma mixtures containing $SO_3 +Хе$ and $SO_3 + Kr$, respectively, are presumably attributed to transitions of exciplexes $XeSO_4^*$ and $KrSO_4^*$ from the lower Coulomb state to the ground state. Proceeding from this assumption, the electron affinity energy of the radical $SO_4$ is estimated to be $ЕА_{SO_4}\approx 4,5$ eV.