On the dissociative ionization of SO₂ in Io's atmosphere

Abstract

Unattenuated ionization rates for the dissociative photoionization of SO₂ producing SO₂⁺, SO⁺, S⁺, O⁺, and O₂⁺ ions are reported during solar minimum and maximum conditions. It is found that in the atmosphere of Io the photo-dissociation-ionization of SO₂ could be an important source of the production of SO⁺, S⁺, O⁺, and O₂⁺ ions and that its contribution is much greater (factor of 5-10) compared with that due to direct photoionization of, respectively, SO, S, O, and O₂ gases. Role of photoelectron impact ionization of SO₂ in producing SO₂⁺, SO⁺, S⁺, O⁺, and O₂⁺ ions in the Io's atmosphere is investigated using a Monte Carlo model. It is recommended that the models of Io's ionosphere-atmosphere should include the dissociative ionization of SO₂.