Oxygen-Isotope Exchange between CO2 and NO2 with Implications for Atmospheric Chemistry.
J Phys Chem Lett
; 15(16): 4430-4436, 2024 Apr 25.
Article
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| MEDLINE
| ID: mdl-38626390
ABSTRACT
Elucidating isotope exchange between atmospheric trace molecular species is important for environment monitoring, climate control studies, and a fundamental understanding of atmospheric chemistry. Here, we provide direct experimental evidence of oxygen-isotopic exchange between carbon dioxide (CO2) and nitrogen dioxide (NO2), which are simultaneously emitted into the atmosphere from common sources. A combined near-infrared and UV-vis optical cavity-enhanced experimental investigation along with quantum-chemical calculations followed by a reaction modeling study revealed that CO2 and NO2 can communicate isotopically by near-ultraviolet-driven NO2 photolysis. Our results found evidence for a near-barrierless (1.67 kcal/mol) nitrate-containing complex having a very short lifetime (â¼13 ns) which facilitates the transfer of 18O-isotopes from 18O12C16O to N16O16O, leading to isotopic depletion of 18O in 18O12C16O, thus opening a new gas-phase isotope-selective chemical transformation mechanism in the lower atmosphere. This isotope exchange study may serve as a new window into the fundamental understanding of isotopic photochemistry, oxygen isotopic fractionations, and climate modeling.
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Bases de datos:
MEDLINE
Idioma:
En
Revista:
J Phys Chem Lett
Año:
2024
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Article
País de afiliación:
India