Classical description of the electron capture to the continuum cusp formation in ion-atom collisions

Abstract

Classical calculations are used to describe the dynamics of the electron capture to the continuum (ECC) cusp formation in ${\mathrm{H}}^{+}+\mathrm{He}$ collisions. We illustrate the frontier character of the ECC electrons between capture and ionization, and confirm that it is a temporary capture, through projectile focusing, that is responsible for the ECC cusp. Furthermore, the cusp is not a divergence smoothed by the experiment, and is slightly shifted from the impact-velocity value because of the residual pull from the target after ionization. This shift is larger the smaller the nuclear velocity.