| Abstract
| - Master equation calculations on a computational potential energy surface reveal that collisionalstabilization at atmospheric pressure becomes important in the gas-phase ozonolysis of endocyclic alkenesfor a carbon number between 8 and 15. Because the reaction products from endocyclic ozonolysis aretethered, this system is ideal for consideration of collisional energy transfer, as chemical activation is confinedto a single reaction product. Collisional stabilization of the Criegee intermediate precedes collisionalstabilization of the primary ozonide by roughly an order of magnitude in pressure. The stabilization of theCriegee intermediate leads to a dramatic transformation in the dominant oxidation pathway from a radical-forming process at low carbon number to a secondary ozonide-forming process at high carbon number.Secondary ozonide formation is important even for syn-isomer Criegee intermediates, contrary to previousspeculation. We use substituted cyclohexenes as analogues for atmospherically important mono- andsesquiterpenes, which are major precursors for secondary organic aerosol formation in the atmosphere.Combining these calculations with literature experimental data, we conclude that the transformation fromchemically activated to collisionally stabilized behavior most probably occurs between the mono- andsesquiterpenes, thus causing dramatically different atmospheric behavior.
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