X-ray measurements of charge transfer reactions involving cold, very highly charged ions

The magnetic trapping mode of the Livermore high-energy Electron Beam Ion T rap is exploited to study charge transfer reactions between cold (few eV/am u) highly charged ions and gases. By selectively puffing neutral gases and monitoring the Xray emission, state-selective measurements of the charge tr ansfer reaction channels are possible. The observed K-shell X-ray spectra s how prominent emission from high-n levels decaying to the n = 1 ground leve l, which is enabled by electron capture into states with low orbital angula r momentum. A comparison with modeling calculations, therefore, allows a de termination of the range of principal and angular momentum quantum numbers involved in the reaction.