Experimental investigation of the mechanisms creating projectile continuum electrons in highly charged ion-atom collisions

Different collision mechanisms, which create continuum electrons that are slow in the rest frame of the ion, have been investigated by zero-degree electron spectroscopy. For the four-electron ions C 2+ , O 4+ and F 5+ , (1s 2 s 2 ) colliding with Ar autoionisation occurs after double-core excitation at high impact velocities. The combination of transfer and excitation, however, becomes an important mechanism, leading to autoionisation at lower impact velocities. For the three-electron ion F 6+ , (1s 2 2s) autoionisation lines were observed only as a result of transfer and excitation in the velocity interval from 3 nu 0 to 8 nu 0 considered. For 20 MeV Au q+ on H 2 , He, and Ar (5<or=q