Double scattering in grazing angle Rutherford backscattering spectra

Developments in the analytic model for double scattering in Rutherford backscattering spectra are presented. It is shown that, in grazing angle of incidence spectra of thin films, the main contribution to the low energy tails comes from particles that after the first collision have a path nearly parallel to the surface of the sample. Thus collisions with small scattering angle must be included, since they-are the only way of achieving such paths. In bulk samples, these trajectories must also be included. Particle loss as the beam enters the sample, as well as angular dependent screening, are taken into account in the model developed. The effect of lateral spread due to multiple scattering is considered, and its influence in the double scattering spectrum is calculated. It is found to be important in the measurement of ultra-thin films in grazing geometry. (C) 2004 Elsevier B.V. All rights reserved.