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Pressure Stabilization of Criegee Intermediates Formed from Symmetric...

Hakala, J. P., and N. Donahue (2018), Pressure Stabilization of Criegee Intermediates Formed from Symmetric trans-Alkene Ozonolysis, J. Phys. Chem. A, 122, 9426-9434, doi:10.1021/acs.jpca.8b09650.

We explore the pressure dependence of a stabilized Criegee Intermediate

Downloaded via CARNEGIE MELLON UNIV on January 3, 2019 at 15:16:48 (UTC). (sCI) formation from a sequence of trans-alkene ozonolysis reactions. To study the effect of carbon chain length on the stabilization, we select five symmetric trans-alkenes ranging from trans-2-butene (C4) through trans-7-tetradecene (C14). We measure the pressure falloff curves for each alkene from 50 to 900 Torr in a flow reactor using conversion of SO2 to H2SO4 with and without an OH scavenger, and subsequent detection of H2SO4 with a nitrate chemical ionization mass spectrometer to constrain sCI yields. As the length of the carbon chain increases, we observe a systematic increase in Criegee Intermediate stabilization at a given pressure, along with a systematic decrease in the low-pressure limit. Our results also suggest that for these symmetrical systems the anticonformer of the Criegee Intermediate stabilizes before (at lower pressure than) the syn conformer.

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Atmospheric Composition
Tropospheric Composition Program (TCP)