COINCIDENCE STUDIES OF CAPTURE AND IONIZATION IN HIGHLY CHARGED IQ+-HE AND UQ+-HE COLLISIONS AT MEDIUM VELOCITIES

Electron capture and ionization processes were investigated for Iq+-He and Uq+-He collisions at incident energies 0.11.0 MeV/nucleon and for incident charge states q=544. Cross sections for single-electron capture, transfer ionization, single ionization, and double ionization were obtained using a projectile-ion recoil-ion coincidence technique. A pronounced interplay among the different electronic processes was observed. Cross sections for single ionization show a rather weak charge-state dependence, in disagreement with recent calculations of McKenzie and Olson [Phys. Rev. A 35, 2863 (1987)]. In a second experiment, photon recoil-ion coincidences were measured to obtain partial cross sections for capture into certain projectile n states. These measurements provide strong evidence that transfer ionization populates lower projectile n states than does single-electron capture. Zero-degree electron spectroscopy, coincident with charge capture for 0.5 MeV/nucleon U30+ projectiles revealed that the free electron in transfer ionization is released from the projectile to its continuum and from high-lying Rydberg states of the projectile. © 1990 The American Physical Society.