Theory of ionization in ion-atom collisions: Spectra of ejected electrons

A Galilean invariant theory of atomic collisions is constructed for straight-line trajectories of nuclei with arbitrary impact parameters, The theory is based on Sturmian expansions in Fourier space, and provides an exact description of excitation and ionization processes for a wide range of collision velocities. Advantages of Sturmian sets over conventional eigenstates are emphasized. Detailed spectra of electrons ejected in head-on ion-atom collisions are calculated.