Dissociative excitation of SO₂ by controlled electron impact

The fragmentation of SO₂ following dissociative electron impact excitation has been studied under single collision conditions for incident electron energies up to 500 eV. The emission spectrum in the far v.u.v. spectral range (450-1100Å) shows many features arising from excited neutral oxygen and ionized oxygen and sulphur fragments. Absolute emission cross sections have been measured for the most intense lines and the maximum values were found to range from 1-12 × 10^-19 cm² with an uncertainty of approx. ± 35%. Dissociation mechanisms are discussed and in some cases the dissociation path could be uniquely identified. The striking differences between the v.u.v. emission spectrum produced by single step dissociation of SO₂ and the spectra emitted by the plasma torus around Jupiter are discussed.