A novel merged beam apparatus to study the cosmic origins of organic chemistry*

We are constructing a novel merged-beams apparatus to study the cosmic origins of organic chemistry. With this, we plan to measure reactions of atomic C with molecular ions. Rate coefficients for such reactions are a critical component of the astrochemical models used to predict interstellar molecular abundances and to analyze spectroscopic observations of molecule-bearing cosmic sources. Initial studies will focus on $\mathrm{C + H^+_3 \rightarrow CH^+ + H_2}$ reactions, an important first step in leading to interstellar organic chemistry. Starting with a $\mathrm{C^-}$ beam, we will use laser photodetachment to generate a C beam; the residual $\mathrm{C^-}$ will then be removed leaving a pure neutral beam. Subsequently an $\mathrm{H^+_3}$ beam will be merged with the C beam. Since the beams will be co-propagating, we will be able to study reactions down to collision energies of the order of ten meV ($\leq 140$ K). Reactions will be studied using an electrostatic analyzer to separate and detect the charged end products, allowing us to determine absolute reaction cross sections.