Absolute differential cross sections for direct scattering of keV O⁺ ions by He, H₂, N₂, and O₂

B. G. Lindsay

J. Geophys. Res. 109, A08305 (2004)

Accurate atomic scattering cross sections are essential for modeling energetic particle precipitation into the upper atmosphere. Here, measurements of absolute differential cross sections for direct scattering of O⁺ ions by He, H₂, N₂, and O₂ are reported. The measured cross sections include contributions from both elastic and inelastic scattering processes. Data are presented for 0.5-, 1.5-, and 5-keV projectile energies over the laboratory angular range 0.22° - 4.68°. Additionally, a simple numerical technique is used to estimate the scattering cross sections for He, N₂, and O₂ at 0.1 keV. At a given energy, the cross sections for different targets exhibit a high degree of similarity in both amplitude and angular dependence. This observation suggests that the cross sections for targets such as O and H, which are much more difficult to study in the laboratory and for which measurements are not available, may be approximated by an average of the data presented here.