Radiative double electron capture (RDEC) involves the transfer of two electrons with the simultaneous emission of a single photon. This process, which can be viewed as the inverse of double photoionzation, has been studied for 2.11 MeV/u F 9+ and F 8+ ions striking gas targets of N2 and Ne. The existence of RDEC is conclusively shown for both targets and the results are compared with earlier O 8+ and F 9+ findings for thin-foil carbon and with theory. The data for the carbon target showed some evidence for the existence of RDEC but the interpretation was clouded by high-probability, unavoidable multiple collisions causing the exiting charge state to be increased.

Radiative double electron capture (RDEC), occurring when two electrons are captured to a projectile ion with the simultaneous emission of a single photon, has been investigated. RDEC can be considered as the time inverse process of double photoionization. Strong evidence for RDEC is found in F 9+ + N 2 collisions, and additionally for one-electron F 8+ for which the probability for the process is expected to be considerably smaller. Preliminary values for the cross sections for RDEC have been determined. A significant advantage of the gas target is that multiple collision effects seen for a solid target are avoided due to the single collision conditions that prevail for gas targets.

Synopsis The first successful observation of radiative double electron capture for gas targets is reported. RDEC has been observed for 2.11 MeV/u F9+,8++N2, Ne collisions. Cross sections for both projectile charge states and targets were determined and compared with previous results and theory. This abstract gives an overview of the results found for both gas targets.