In this work we present a theoretical treatment of electron ejection from a clean metallic semi- infinite solid with an ideal orthorhombic Bravais lattice following the impact of moderately fast charged particles with respect to the Fermi momentum of the initially bound electron. For an aluminum semi- infinite solid target multiple differential cross sections have been evaluated using a jellium- type wave function of the undisturbed surface in the initial state. Image- charge final- state electron- surface interactions have been included as well as the scattering of the projectile from the multicenter bulk potential. From a kinematic analysis of the process various ionization mechanisms are inferred and confirmed by the present dynamical model.