Classical two-center effects in ejected-electron spectra from $p^{+}$, $p^{\mathrm{-}}$, and ${\mathrm{He}}^{2+}$+He collisions at intermediate energies

Doubly and singly differential cross sections for electron emission have been calculated by means of the classical trajectory Monte Carlo method for the $p^{+}$, $p^{\mathrm{-}}$, and ${\mathrm{He}}^{2+}$+He systems at impact energies of 50 and 100 keV/amu. The calculations for the $p^{+}$ and ${\mathrm{He}}^{2+}$+He systems exhibit the capture to the continuum peak and agree in both shape and magnitude with experimental data. Analysis of the classical trajectories has helped to understand the dynamical formation of this peak. The dependence of the cross sections on the projectile charge (-1, +1, and +2) is analyzed and compared with first-order scalings. It is concluded from this analysis that the combined influence of both the projectile and target Coulomb fields prevails over all the electronic spectra.