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 trap is exploited to study charge transfer reactions between cold (few eV/amu) highly charged ions and gases. By selectively puffing neutral gases and monitoring the X-ray emission, state-selective measurements of the charge transfer reaction channels are possible. The observed K-shell X-ray spectra show prominent emission from high-n levels decaying to the n=1 ground level, which is enabled by electron capture into states with low orbital angular momentum. A comparison with modeling calculations, therefore, allows a determination of the range of principal and angular momentum quantum numbers involved in the reaction. (orig.)