Electron-impact ionization of He+:: consequences for double ionization of He in strong laser fields

A B-spline-based approach has been developed for the determination of electron-impact excitation and ionization cross sections for e(-)-He+ collisions. Good agreement is obtained with the convergent-close-coupling approach and with experiment. In order to assist the description of electron scattering processes occurring in strong laser fields, we separate the contributions from singlet states and from triplet states. Since the cross sections for 100% singlet scattering are significantly larger than those for 100% triplet scattering, one needs to take the symmetry of the initial state into account when obtaining estimates for double ionization in strong laser fields using a recollision model.