Reexamining if long-livedN−anions are produced in fast dissociative electron-capture collisions

Abstract

The existence of long-lived states of N − has been a topic investigated with conflicting experimental results. Highly excited spin-aligned states, however, were predicted to have long lifetimes and even be stable against autodetachment. We repeated the measurements of N − formation in 0.9 MeV N 2 + Ar charge-exchange collisions and found that the ions reported previously as N − [Heber et al., Phys. Rev. A 38, 4504 (1988)] are an O − fragment from a 0.9 MeV H 2 NO + impurity beam. This result adds to the comulating data indicating that N − is not going to affect carbon dating measurements using accelerator mass spectrometry.