An analytical energy-loss line shape for high depth resolution in ion-beam analysis

The knowledge of the energy-loss distribution in a single ion-atom collision is a prerequisite for subnanometric resolution in depth-profiling techniques such as nuclear-reaction profiling (NRP) and medium energy ion-scattering (MEIS). The usual Gaussian approximation specified by the stopping power and energy straggling is not valid for near surface regions of solids, where subnanometric or monolayer resolution can be achieved. In this work we propose an analytical formula for the line shape to replace the usual Gaussian distribution widely used in low-resolution ion-beam analysis. Furthermore, we provide a simple physical method to derive the corresponding shape parameters. We also present a comparison with full coupled-channel calculations as well as with experimental data at nearly single collision conditions.