Theoretical studies of triple differential cross sections for electron impact ionization with neon and neon-like ions

Abstract

Electron impact single ionization of atom or molecule, the so-called (e, 2e) reaction, is one of the basic collision processes between electron and atom or molecule. The triple differential cross section (TDCS) of the collision process can provide important data for gas discharge, celestial bodies, and electron-target interaction. A large number of experimental and theoretical studies of (e, 2e) reactions on atom targets have been carried out under different geometric conditions, such as coplanar symmetric geometry, coplanar asymmetric geometry, non-coplanar symmetric geometry, etc. However, few experimental researches of (e, 2e) reaction on ion target have been reported due to the low target source density. The difference in TDCS between atomic target and ionic target can provide more information about the (e, 2e) reaction. Thus the relevant researches on ionic targets are of significance. In this paper, adopting distorted-wave Born approximation (DWBA), the TDCSs of 2 p orbital for Ne and neon-like ions are calculated at different outgoing electron energies (3, 5, 7.5, 10, 15, 20, 30, and 50 eV) under the condition of coplanar symmetric geometry. The results indicate that the TDCSs decrease with the increase of outgoing electron energy and nuclear charge number Z. Except Ne, the TDCSs of other ions present a new structure at an outgoing electron angle of about 150. The intensity of the new structure increases with the increase of the outgoing electron energy in a region of 10-20 eV, while it decreases with the increase of the outgoing electron energy in a region of 20-50 eV. We propose a kind of double-binary collision process to rationalize the new structure. The incident electron ionizes the target atom and the following two outgoing electrons exit in the directions symmetric with respect to the incident electron direction. Then these two outgoing electrons are elastically scattered by the target ions and emitted in the backward directions. In order to confirm this explanation, we compare our calculation results with the previously reported experimental and theoretical results of elastic scattering between electron and Ne. Previous research results show that the elastic scattering cross section has a large intensity at a scattering angle of~150, and it reaches the largest intensity at an outgoing electron energy of 20 eV. These structural features are consistent with our calculated results, implying that our proposed process is reasonable.