  In this paper we discuss how through the process of applying the Fourier
transform to solutions of the Schr\"odinger equation in the Close Coupling
approach, good results for the ionization differential cross section in energy
for electrons ejected in ion-atom collisions are obtained. The differential
distributions are time dependent and through their time average, the comparison
with experimental and theoretical data reported in the literature can be made.
The procedure is illustrated with reasonable success in two systems, $p+H$ and
$p+He$, and is expected to be extended without inherent difficulties to more
complex systems. This allows advancing in the understanding of the calculation
of ionization processes in ion-atom collisions.
