ENERGY-LOSSES OF IONS IMPLANTED IN MATTER

A set of simple and accurate formulae for the first four moments of nu clear and electronic energy losses is proposed. A new variable is intr oduced to include the finite maximum-impact-parameter effect in the nu clear stopping process, which is assumed to be infinite in most studie s. A critical energy at which the electronic energy loss is equal to t he nuclear energy loss is also defined. It determines whether the nucl ear or the electronic stopping process is the dominant mechanism in te rms of incident-ion energy. The critical energy increases for heavy io ns implanted in heavy target materials during the first moment of ener gy loss. The second moment of electronic energy loss is important only for light ions implanted at high ion energies. The third and fourth m oments of nuclear energy loss are much larger than those of the electr onic energy loss for all ion-target combinations. Theoretical predicat ions of the projected ranges and range stragglings for gold ions impla nted in carbon films are close to the experimental data when these pro posed four moments of nuclear and electronic energy losses are conside red.