Charge transfer and ionization in low-energyArq++ Ne collisions

A secondary-ion recoil source was used to study charge transfer and ionization in collisions of ${\mathrm{Ar}}^{q+} \left(2\mathrm{}\le q\le 9\right)$ on Ne at projectile energies between 100 and 1100 eV per projectile charge. Two experimental methods are presented. With the first one we measure cross sections for electron capture by detecting both the initial and final charge states of the Ar ions. With the second method we measure, in addition to those parameters, the charge state of the Ne ions after the reaction. This three-parameter method allows us to distinguish among various competing reaction mechanisms and to measure cross sections for single- and multiple-electron capture, ionization, and transfer ionization. We find that the cross sections for ionization without simultaneous capture are negligibly small, whereas those for transfer ionization are quite important in several cases.