Resonant Behavior in the Projectile X-Ray Yield Associated with Electron Capture in S + Ar Collisions

Experimental evidence is presented for a new resonant process in ion-atom collisions which is analogous to dielectronic recombination in free-electron-ion collisions. Resonant behavior observed in the yield of projectile $K$ x rays in coincidence with single-electron capture in 70-160-MeV S + Ar collisions is attributed to simultaneous electron capture and $K$-shell excitation. The data indicate that this resonant process is an important mechanism in inner-shell vacancy production in the energy range studied.