Dynamic response of target electrons on elastic scattering cross sections for heavy-ion impact on a high-Z atom - art. no. 012718

摘要

Large-angle elastic scattering cross sections were measured for medium energy He+ and Ne+ ions impact on Ni, Sb, and Hf atoms and the results are compared with those calculated using screened interatomic potentials. As the screened Coulomb potential, we employed the Moliere, Ziegler-Biersack-Littmark (ZBL), and that calculated numerically by solving the Poisson equation applied to the Hartree-Fock (HF) atomic model. For He+ impact, the ZBL and HF (He2+ is assumed) potentials reproduced well the observed scattering cross sections but the Moliere potential underestimated them significantly. Surprisingly, however, for Ne+ impact on Sb and Hf, the observed scattering cross sections were much larger than those calculated from all the above screened interatomic potentials, although Ne10+ was assumed for the HF potential. In a large-angle collision, a projectile heavy ion attracts the target electrons to distort the electron cloud and as a result it changes the electric field upon the projectile. The observed scattering cross sections are reproduced well by assuming a simple model that the center of gravity of the target electrons slightly shifts toward the projectile by 0.09-0.12 Angstrom for Hf and 0.066-0.070 Angstrom for Sb from the nucleus. [References: 15]