Carbon Atom Reactivity with Amorphous Solid Water: H$_2$O Catalyzed Formation of H$_2$CO. (arXiv:2110.15887v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Molpeceres_G/0/1/0/all/0/1">Germán Molpeceres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kastner_J/0/1/0/all/0/1">Johannes Kästner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fedoseev_G/0/1/0/all/0/1">Gleb Fedoseev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Qasim_D/0/1/0/all/0/1">Danna Qasim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schomig_R/0/1/0/all/0/1">Richard Schömig</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Linnartz_H/0/1/0/all/0/1">Harold Linnartz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lamberts_T/0/1/0/all/0/1">Thanja Lamberts</a>
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.
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.
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