Electron Production in Collisions between Light Ions and Rare Gases: The Importance of the Charge-Transfer and Direct-Ionization Channels

Coincidence measurements were performed to separate the charge-transfer and directionization channels for 15-100-keV ${\mathrm{H}}^{+}$, ${\mathrm{He}}^{+}$ collisions with Ne,Ar,Kr. Absolute cross sections are given for the production of single and multiple ionization of the target by these two ionization mechanisms. It is demonstrated that as the collision system becomes heavier, the multiple ionization components of these two channels become increasingly more important, and the production of free electrons results primarily from higher-order charge-transfer channels—not from direct single target ionization.