An extended formula for the energy spectrum of sputtered atoms from a material irradiated by light ions

We extend a formula proposed by Kenmotsu et al. (hereafter Paper I), which fits with the energy spectrum of atoms sputtered from a heavy material hit by low-energy light ions (H+, D+, T+, He+) by taking into account an inelastic energy loss neglected in Paper I. We assume that primary knock-on atoms produced by ions backscattered at large angles do not lose energy while penetrating the material up to the surface, instead of the energy-loss model used in Paper I. The extended formula is expressed in terms of a normalized energy-distribution function and is compared with the data calculated with the ACAT code for 50 eV, 100 eV and 1 keV D+ ions impinging on a Fe target. Our formula fits well with the data in a wide range of incident energy.