Double scattering of ions from polycrystalline materials

In this paper double scattering of ions from polycrystalline materials has been theoretically investigated. It is shown that double collision events contribute to the yield at low energy as well as to the high energy flanks of the peaks depending on whether or not the azimuthal angle ø₁ is greater than or less than a critical angle ø_1c at a given first scattering angle θ₁. There are various combinations of first scattering angle θ₁ and second scattering angle θ₂ which give the required retained energy in two successive collisions. Scattering cross sections derived from the Bohr potential and a double interpolation sub-routine are used to calculate the scattering yield at various angles. Two systems, Ne⁺ scattered from copper and Ar⁺ scattered from gold, each at 30 keV primary energy, have been compared with experimental results.