2-CENTER ELECTRON-EMISSION IN COLLISIONS OF FAST, HIGHLY-CHARGED IONSWITH HE - EXPERIMENT AND THEORY

Electron emission cross sections differential in energy and angle of t he ejected electrons were measured in collisions of 5-MeV/mu C6+, O8+, and Ne10+ ions on He. The experimental results deviate substantially from calculations based on the plane-wave Born approximation indicatin g that the ejected electrons are significantly affected by the two-cen ter field of the target and projectile ion. The two-center effects wer e confirmed by comparison with results from the continuum-distorted-wa ve-eikonal-initial-state (CDW-EIS) approximation that has recently bee n improved by using Hartree-Fock-Slater wave functions for the ejected electrons. It is shown for nearly complete energy and angular ranges that the improved CDW-EIS method predicts cross sections in excellent agreement with experiment.