Electron-impact ionization of a hydrogenic ion.

Abstract

An approach to calculate the triple differential cross sections (TDCS) for ionization of hydrogenic ions by electron impact in the intermediate- and high-energy regime and for asymmetric geometry is proposed. The theoretical model is particularly suitable for asymmetric geometry since the two outgoing electrons are treated on unequal footings. The final-state wave function, in the present prescription, involves the electron-electron correlation term and satisfies the asymptotic three-body boundary condition of an ionization process for asymmetric geometry (i.e., for ${\mathit{k}}_{1}$\ensuremath{\gg}${\mathit{k}}_{2}$). As is well known, this is one of the most important factors for the prediction of reliable ionization cross sections. The long-range Coulomb interaction occurring in the initial channel has been taken into account properly. TDCS results have been computed for ionization of the ${\mathrm{He}}^{+}$ ion for incident energies of 250, 500, and 1000 eV for fixed values of ejected energy (5 eV) and scattering angle (4\ifmmode^\circ\else\textdegree\fi{}). A large recoil peak is noted in the TDCS structure at lower energies (e.g., 250 eV).