Sputtering of SO₂ by high energy ions

Abstract

Sputtering yields of solid SO₂ by high energy ions were measured in order to study the mechanism for sputtering dielectrics with ions in the electronic stopping power region. The incident ions were helium and fluorine with energies ranging from 1.5 MeV to 25 MeV. Yields as high as 7000 SO₂ molecules/incident F ion were measured; the 1.5 MeV ⁴He beam had a sputtering yield of 50. The data are compared to yield measurements made on UF₄ and H₂O targets. There is a striking similarity in the yield as a function of the incident F energy for all three targets. The data compare favorably with theoretical yield curves based on a new model for the sputtering which considers the electronic excitations induced in the target by the incident beam. Measurements and calculations of this sort are also useful in understanding processes which occur on the surface of Jupiter's satellite Io, which is covered with SO₂ frost and bombarded by energetic ions trapped in the Jovian magnetosphere.