Beam dispersion of ions penetrating through an amorphous compound binary layer

Based on Monte Carlo simulations, we calculated the beam dispersion of ions penetrating through an amorphous binary compound layer with the atomic number of compositional elements ranging from Z = 5 to Z = 80. The scattering probabilities were compared with that obtained by approximating the compound layer as a monatomic target with mean atomic number and mean atomic mass. Very good agreement is observed between the two approaches for the compound substrate having close atomic numbers. An appreciable difference is observed for the substrate having considerably different atomic numbers. However, such differences disappear when the transition from single scattering (corresponding to an ultra thin layer) to multiple scattering (corresponding to a relatively thick layer) occurs. The study reveals the factor determining the validity and limits of the approximation method in studying scattering phenomena, with the motivation to provide a method to easily estimate the dechanneling of an ion beam passing through a crystalline compound target having a surface amorphous layer.