Angular, energy and charge distribution in the scattering of low-energy helium ions by an amorphous silicon surface

We have performed an experimental investigation of the angular distribution of LEIS spectra and the charge fraction for the 4 keV system at 6 and of incidence angle. A numerical model is developed in order to assure a quick adjustment of several parameters. The influence of the electronic stopping power, the charge exchange in close collisions, the Auger neutralization, the expansion of electronic density outside the bulk and the image charge effect are studied and discussed. A good agreement is found between the experimental results and the numerical calculation.