NEUTRALIZATION AND IONIZATION OF LOW-ENERGY HELIUM IONS SCATTERING FROM A COPPER SURFACE

Ion yield measurements are presented of 2-10 keV helium ions scattered from a copper (100) face. The scattering angle is 30 degree . The results are explained using a charge transfer model originally proposed by the authors. The model takes into account Auger neutralization as well as ionization and neutralization resulting from a violent collision. The present results are compared with previous experiments in which a primary atom beam was used. Within the experimental errors the results of both experiments can be explained using the same charge exchange parameters. A second result of the present investigation is that more convincing evidence is given for the occurrence of neutralization during the violent collision by a non-Auger process. It is probable that this process, as well as the ionization process, results from an interaction between the helium particle and the copper L shell electrons.