HIGH-ENERGY RECOIL-ION EMISSION IN KEV HEAVY-ION SURFACE COLLISIONS

For keV Xe+, Kr+ and Ar+ ions incident at 30 degrees on Cu(110) we hav e observed the emission of negatively charged particles with energies up to about 40% of the primary energy. Bq. time-of-flight techniques w e have found that electrons are emitted with energies : up to 80 eV. w hereas the negatively charged high-energy. particles are Cu-recoil ion s, High-energy Cu I ions have also been found. Simple energy and momen tum conservation arguments show that such high recoil energies are ind eed possible for multiple collision events in which the primary recoil ion scatters off one or more Cu atoms. (C) 1997 Elsevier Science B.V.