Radiative Double-Electron Capture by Bare and One-Electron Ions on Gas Targets

Abstract

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.

Preliminary Results for Observation of Radiative Double-Electron Capture by F9+,8+ on Graphene

“…Given the thickness of the target, these values appear reasonable. [11] and the most accurate theoretical model to date (this includes two, labeled A, which includes all target electrons, and K, which includes only the innermost target electrons) (b), and F 9+,8+ and gas N 2 and Ne targets (c) [10].…”

“…The GSI group in Darmstadt conducted one final investigation for 30 MeV/u Cr 24+ on He and N 2 , with no evidence of RDEC reported [9]. Finally, from WMU the most definitive observation of RDEC was reported for 2.11 MeV/u F 9+,8+ projectiles incident on N 2 and Ne gas targets [10], followed by 2.11 MeV/u F 9+,8+ and 2.19 MeV/u O 8+,7+ on thin-foil C [11]. The latter works are summarized and further explored in Tanis et al [12].…”

“…Figure 5. Present tentative cross sections for 2.11 MeV/u F 9+ and F 8+ on graphene (a), compared with our earlier experimental results for O 8+,7+ (Z = 8) and F 9+,8+ (Z = 9) and thin-foil C target[11] and the most accurate theoretical model to date (this includes two, labeled A, which includes all target electrons, and K, which includes only the innermost target electrons) (b), and F 9+,8+ and gas N 2 and Ne targets (c)[10].…”