Carbon Atom Reactivity with Amorphous Solid Water: H$_2$O Catalyzed Formation of H$_2$CO

Germán Molpeceres; Johannes Kästner; Gleb Fedoseev; Danna Qasim; Richard Schömig; Harold Linnartz; Thanja Lamberts

doi:10.1021/acs.jpclett.1c02760

paper

Carbon Atom Reactivity with Amorphous Solid Water: H $_{2}$ O Catalyzed Formation of H $_{2}$ CO

arXiv:2110.15887 · doi:10.1021/acs.jpclett.1c02760

Abstract

We report new computational and experimental evidence of an efficient and astrochemically relevant formation route to formaldehyde (H $_{2}$ CO). This simplest carbonylic compound is central to the formation of complex organics in cold interstellar clouds, and is generally regarded to be formed by the hydrogenation of solid-state carbon monoxide. We demonstrate H $_{2}$ CO formation via the reaction of carbon atoms with amorphous solid water. Crucial to our proposed mechanism is a concerted proton transfer catalyzed by the water hydrogen bonding network. Consequently, the reactions $^{3}$ C + H $_{2}$ O -> $^{3}$ HCOH and $^{1}$ HCOH -> $^{1}$ H $_{2}$ CO can take place with low or without barriers, contrary to the high-barrier traditional internal hydrogen migration. These low barriers or absence thereof explain the very small kinetic isotope effect in our experiments when comparing the formation of H $_{2}$ CO to D $_{2}$ CO. Our results reconcile the disagreement found in the literature on the reaction route: C + H $_{2}$ O -> H $_{2}$ CO.

Accepted for publication in JPCL

Carbon Atom Reactivity with Amorphous Solid Water: H2​O Catalyzed Formation of H2​CO

Abstract

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Carbon Atom Reactivity with Amorphous Solid Water: H $_{2}$ O Catalyzed Formation of H $_{2}$ CO