Resonant-transfer-and-excitation for highly charged ions (16<=Z<=23) in collisions with helium

Significant new evidence is presented for resonant-transfer-and-excitation (RTE) in ion-atom collisions. This process occurs when a target electron is captured simultaneously with the excitation of the projectile followed by deexcitation via photon emission. RTE, which is analogous to dielectronic recombination (DR), proceeds via the inverse of an Auger transition, and is expected to be resonant for projectile velocities corresponding to the energy of the ejected electron in the Auger process. RTE was investigated by measuring cross sections for projectile K X-ray emission coincident with single electron capture for 15-200 MeV 16S13+, 100-360 MeV 20Casup(16+,17+,18+) and 180-460 MeV 23Vsup(19+,20+,21+) ions colliding with helium. Strong resonant behavior, in agreement with theoretical calculations of RTE, was observed in the coincidence cross sections. (orig.)