Proposed Development of a Novel Approach for Studying Anion-Neutral Reactions*

We propose a new method for studying anion-neutral reactions. We will use fast, merged anion-neutral beams and detect the charged end products. This novel approach will utilize the ion- atom merged-beams apparatus, a unique state-of-the-art facility located at Oak Ridge National Laboratory, and expand its capabilities by adding a detection system to collect detached product electrons. Future extensions will allow us to detect product anions. Laboratory beam energies will be in the keV range; but because the beams run co-linear, center-of-mass energies from the meV to keV range can be achieved. Proof-of- principle measurements will be carried out using the associative detachment process ${\mathrm H}^- + {\mathrm H} \to {\mathrm H}_2^- \to {\mathrm H}_2 + {\mathrm e}^-$. Published values for this reaction range over a factor of 5. The situation is little better for the time-reverse dissociative attachment process ${\mathrm H}_2 + {\mathrm e}^- \to {\mathrm H}_2^- \to {\mathrm H}^- + {\mathrm H}$. Our proposed research will help to resolve this issue. Future possible research directions include adding a cold molecular anion source in order to study reactions such as ${\mathrm X} + {\mathrm Y} {\mathrm Z}^-$. This will allow investigations into a wide range of anion-neutral reactions.