Energy Distribution in Sputtering Processes

The energy distribution $N_i\left(E_i\right)d{E}_i$ of the recoil atoms within polycrystalline targets of Al, Ti, Ni, Cu, and Ag under bombardment with ${\mathrm{Ar}}^{+}$ ions of 900 eV are deduced from the measured energy distributions of neutral sputtered particles in the energy range below 20 eV. It is found that $N_i\left(E_i\right)\sim {\left(\frac{E_i}{S}\right)}^{-2\mathrm{}}$, where $S$ describes the binding energy within the bombarded solid.