| Autor: |
Garrod RT; Depts. of Chemistry & Astronomy, University of Virginia, Charlottesville, VA 22904, USA. rgarrod@virginia.edu., Herbst E; Depts. of Chemistry & Astronomy, University of Virginia, Charlottesville, VA 22904, USA. rgarrod@virginia.edu. |
| Jazyk: |
angličtina |
| Zdroj: |
Faraday discussions [Faraday Discuss] 2023 Sep 20; Vol. 245 (0), pp. 541-568. Date of Electronic Publication: 2023 Sep 20. |
| DOI: |
10.1039/d3fd00014a |
| Abstrakt: |
Complex, nitrogen-bearing interstellar molecules, especially amines, are targets of particular interest for detection in star- and planet-forming regions, due to their possible relevance to prebiotic chemistry. However, these NH 2 -bearing molecules are not universally detected in sources where other, oxygen-bearing complex organic molecules (COMs) are often plentiful. Nevertheless, recent astrochemical models have often predicted large abundances for NH 2 -bearing complex organics, based on their putative production on dust grains. Here we investigate a range of new gas-phase proton-transfer reactions and their influence on the destruction of COMs. As in past studies, reactions between protonated COMs and ammonia (NH 3 ) are found to be important in prolonging gas-phase COM lifetimes. However, for molecules with proton affinities (PA) greater than that of ammonia, proton-transfer reactions result in drastic reductions in abundances and lifetimes. Ammonia acts as a sink for proton transfer from low-PA COMs, while passing on protons to high-PA species; dissociative recombination with electrons then destroys the resulting ions. Species strongly affected include methylamine (CH 3 NH 2 ), urea (NH 2 C(O)NH 2 ) and others bearing the NH 2 group. The abundances of these species show a sharp time dependence, indicating that their detectability may rest on the precise chemical age of the source. Rapid gas-phase destruction of glycine (NH 2 CH 2 COOH) in the models suggests that its future detection may be yet more challenging than previously hoped. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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