Resonant behavior in the projectile K x-ray yield associated with electron capture in ion-atom collisions

A review of recent effects to observe simultaneous electron capture-and-K-shell excitation in ion-atom collisions is presented. This process is qualitatively analogous to dielectronic recombination (inverse Auger transition) in free-electron-ion collisions, and, hence, is expected to be resonant. Experimentally, events having the correct signature for simultaneous capture-and-excitation are isolated by detecting projectile K x rays in coincidence with ions which capture a single electron. In a recent experiment involving 70-160 MeV S13+ ions incident on Ar, resonant behavior was observed in the yield of projectile K x rays associated with electron capture. This resonance is attributed to simultaneous capture-and-excitation. The position (120 MeV) and width (60 MeV) of the observed resonance are in good agreement with theoretical calculations. The data indicate that this resonant process is an important mechanism in inner-shell vacancy production in the energy range studied. 11 references, 4 figures, 1 table