Abstract
Starting from a simple atomic model by Lindhard giving a power potential between ions and atoms as V(r)=z1z2e2an-1/nrn, we assumed that the first collision with a metal atom is of the weakly screened type (n=2) or Rutherford type (n=1) and that subsequent collisions of displaced atoms are similar to collisions of hard spheres (n=5). On this basis, consistent expressions were obtained for the maximum yield Smax with the corresponding energy Em for n=2, and the universal curve of yield-energy, which on the number of atms in the target materials per unit volume N, the effective atomic radius a and the displacement energy Ed. The results were in good agreement with experiments over the energy range from 50 eV to 500 keV.