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A theoretical ab initio study on the H(2)NO + O(3) reaction.
Julio Peiró-García1, Víctor M Ramírez-Ramírez, Ignacio Nebot-Gil
1Departamento de Química Física, Facultad de Química, Universidad de Valencia, c/ Dr Moliner, 50, E-46100, Burjasot (Valencia), Spain.
Journal of Computational Chemistry
|June 27, 2003
Summary
The NH(2) + O(3) reaction shows unusual decay patterns at high ozone levels. Theoretical calculations reveal that the H(2)NO radical regenerates NH(2) radicals, explaining the observed experimental deviations.
Area of Science:
- Atmospheric Chemistry
- Chemical Kinetics
- Theoretical Chemistry
Background:
- The NH(2) + O(3) reaction exhibits anomalous pseudo-first-order decay kinetics at elevated ozone concentrations.
- This deviation is hypothesized to result from NH(2) radical regeneration by ozone reactions with reaction products.
Purpose of the Study:
- To provide a theoretical explanation for the observed kinetic behavior of the NH(2) + O(3) system.
- To investigate the proposed regeneration pathways involving the H(2)NO radical.
Main Methods:
- Ab initio electronic structure calculations were performed.
- The reactions of H(2)NO with O(3) were theoretically modeled.
Main Results:
- The study focused on two potential reactions of H(2)NO with O(3).
- Calculations confirmed that only the H(2)NO + O(3) --> NH(2) + O(2) reaction regenerates NH(2) radicals.
- The alternative pathway, H(2)NO + O(3) --> HNO + OH + O(2), was not found to regenerate NH(2).
Conclusions:
- The theoretical findings support the regeneration of NH(2) radicals via the H(2)NO + O(3) --> NH(2) + O(2) reaction.
- This mechanism explains the experimentally observed deviation in the pseudo-first-order decay of NH(2) at high ozone pressures.