Differential cross section measurements for elasticscattering of electrons by highly charged argonions

Abstract

Elastic scattering of electrons by highly charged ions, inparticular the measurements of differential cross sections,is the focus of the present research. By using a150° crossed beam method, we have successfullymeasured the angular distributions of electrons elasticallyscattered from Ar7+ and Ar8+ ions over a wideangular range, employing a novel toroidal electron energyanalyser, which is capable of simultaneous determination ofthe angle and the energy of the scattered electrons over a widerange. Relative differential cross sections for the e + Ar7+ system have been derived by employing results ofe + Ar8+, which can be treated as pure Rutherfordscattering, as a calibration for the detection efficiency overthe angular range. In the angular range studied, between34°-85°, experimental data of the e + Ar7+ system agree with the Rutherford classical crosssections fairly well, indicating that the Coulombic interactiondominates over this angular range, at a collision energy of100 eV. Some small deviations from the Rutherford cross sectionsare considered to be due to the influences of the ionic structureto the scattering cross sections.