Mass spectrometric study of the binary approximation in scattering of low energy ions from solid surfaces

Abstract

The validity of the binary collision approximation (in a “single scattering” event) when low energy inert gas ions are scattered from the surface of a copper target was investigated. He and Ne ions of energies 20–1000 ev were incident on the surface of a polycrystalline target at 45°; ions scattered at 90° with respect to the incident beam direction were analyzed using a magnetic sector mass spectrometer. The scattered ions were identified and their energies measured. The binary collision approximation was found to be valid for primary ion energies as low as 40 ev for the HeCu system, and 20 ev for the NeCu system. No evidence of an increased “effective mass” of the target atoms was found.