We present total single- and double-ionization cross sections for the collision systems pbar + He and pbar + Li+ in the 1–1000 keV impact energy range with emphasis on microscopic response effects during the collision. The calculations rely on the basis generator method. In both collision systems, the response of the effective electronic interaction to the time-dependent density reduces the ionization cross section at low impact energies significantly. It is shown, in comparison with other theories, that this reduction is a consequence of time-dependent screening rather than due to dynamical correlation effects

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True one-electron collision systems provide an ideal testing ground for theory. Absolute cross sections for charge transfer in the collision systems Li2+ + He2+ and Li2+ + Li3+ have been measured for centre-of-mass energies between 52 and 148 keV and 6 and 63 keV, respectively. The data are compared with calculations using the two-centre basis generator method. A fair agreement between the experimental data and the calculations is found.

New experimental and theoretical data for the degree of linear polarization of Lyman-α emission induced by proton and antiproton impact on atomic hydrogen in the 1–1000 keV impact energy range are presented. For the calculations a two-centre extension of the basis generator method is used to solve the time-dependent Schrödinger equation. In the experimental part we present new measurements for the polarization fraction of the impact induced Lyman-α radiation in the energy range from 13 keV to 800 keV for the collision system p + H. The calculated polarization fractions are in very good agreement with the experimental data.

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