We report observation of a significant enhancement in the intensity of target and projectile autoionizing electrons produced in low-energy (2–15 keV) ${\mathrm{He}}^{+}$+He collisions. The target electron intensity is strongly peaked at 0° and confined to an angular range of ≊5° about the incident beam direction, while the projectile electron intensity shows a similar enhancement at 180°. We attribute this effect to Coulomb focusing, a new aspect of post-collision interaction which results from the deflection of the ejected electrons in the Coulomb field of the receding spectator ion.

• Received 13 February 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.35