Proton impact excitation of SO2

Abstract

Because of the interest in atomic emissions observed from the Io plasma torus, we have investigated the spectrum produced by proton impact on SO2 in the wavelength region of 380–800 nm. The proton energy was varied from 50 to 225 keV. The spectrum shows numerous S, O, S+, and O+ lines. A weak series of SO2 bands has also been tentatively identified. In addition, Balmer series lines are seen, which indicates charge‐transfer ionization of the SO2 target. Preliminary absolute emission cross sections on the order of 10−18 cm2 have been measured for the most dominant line in the spectrum, an oxygen triplet at 777 nm.