Genesis of Polyatomic Molecules in Dark Clouds: CO$_2$ Formation on Cold Amorphous Solid Water

Abstract: Understanding the formation of molecules under conditions relevant to interstellar chemistry is fundamental to characterize the chemical evolution of the universe. Using reactive molecular dynamics simulations with model-based or high-quality potential energy surfaces provides a means to specifically and quantitatively probe individual reaction channels at a molecular level. The formation of CO$_2$ from collision of CO($^1 \Sigma$) and O($^1$D) is characterized on amorphous solid water (ASW) under conditions typical in cold molecular clouds. Recombination takes place on the sub-nanosecond time scale and internal energy redistribution leads to stabilization of the product with CO$_2$ remaining adsorbed on the ASW on extended time scales. Using a high-level, reproducing kernel-based potential energy surface for CO$_2$, formation into and stabilization of CO$_2$ and COO is observed.