DYNAMIC SCREENING OF THE (e,2e) PROCESSES FOR LOW-ENERGY ELECTRON IMPACT IONIZATION OF HELIUM

Abstract

Based on the modified three-body Sommerfeld parameters,the effective shield of the residual electron in the final state of He+ is further modified for (e,2e) processes- Such a modification represents a dynamic screening of the four bodies in the final state- The triple differential cross sections for electron impact ionization of atomic helium at an incident energy of 50eV in the asymmetric geometry are calculated by use of the modified Sommerfeld parameters-The results were compared with those of the absolute measurements and the only existing theoretical results of the convergent colse-coupling method-It was found that the present results give a better description for the experimental data at fixed ejected energy of 10eV-

The effect of wave function orthogonality on the simultaneous ionization and excitation of helium

“…[1][2][3] Since early experiments in 1968, much effort has been devoted to studying the ionization processes in which the residual ion is left in the ground state, and the physics behind the experimental measurements has been well understood based on theoretical calculations. [4][5][6][7][8] In contrast, the relevant processes of simultaneous ionization and excitation which leaves the residual ion in an excited state have been much less studied. Experimentally, it is more difficult to measure the triple differential cross sections (TDCSs) for simultaneous ionization and excitation due to the fact that the count rates are two times smaller than the processes of single ionization without excitation.…”