Merged beams studies for astrobiology

The chain of chemical reactions leading towards life is thought to begin in molecular clouds when atomic carbon and oxygen react with H$_3^+$, leading to the formation of complex organic molecules and of water. Uncertainties in the rate coefficients for these reactions hinder our ability to understand the first links in the chemical chain leading towards life. Theory and experiment have yet to converge in either the magnitude or temperature dependence. We have developed a novel merged beam apparatus to study these reactions at the low collision energies relevant for molecular cloud studies. Photodetachment of atomic anion beams is used to produce beams of neutral C and O, each in their ground term as occurs in molecular clouds. The neutral beam is then merged with a velocity matched, co-propagating H$_3^+$ beam. The merged beams method allows us to use fast beams (keV in the lab frame), which are easy to handle and monitor, while being able to achieve relative collision energies down to $\approx 10$ meV. Using the measured merged-beams rate coefficient, we are able to extract cross sections that we can then convolve with a Maxwellian energy spread to generate a thermal rate coefficient for molecular cloud temperatures. Here we report recent results.