biostudies-literaturePeltola JResearch Council of FinlandHelsingin Yliopisto5331-5336https://www.ebi.ac.uk/biostudies/studies/S-EPMC11389976biostudies-literatureUnknown15(20)We report the first direct kinetic measurements of a cyclic stabilized Criegee Intermediate. We have measured the unimolecular reaction rate coefficient of cyclohexanone oxide (c-(CH2)5COO) in the temperature 213-296 K and pressure 7-50 Torr ranges using absorption spectrometry. The c-(CH2)5COO was produced by the photolysis of c-(CH2)5CIBr at 213 nm in the presence of O2. We compare the measured fast c-(CH2)5COO unimolecular rate coefficient, 1998 ± 147 s-1 at 296 K, with the literature calculations for the structurally similar E-nopinone oxide formed in β-pinene ozonolysis. The kuni(c-(CH2)5COO)/The journal of physical chemistry lettersDirect Kinetic Measurements of a Cyclic Criegee Intermediate; Unimolecular Decomposition of c-(CH2)5COO.PMC11389976346374298910Heinonen PPeltola JEskola AfalseDirect Kinetic Measurements of a Cyclic Criegee Intermediate; Unimolecular Decomposition of c-(CH2)5COO.We report the first direct kinetic measurements of a cyclic stabilized Criegee Intermediate. We have measured the unimolecular reaction rate coefficient of cyclohexanone oxide (c-(CH2)5COO) in the temperature 213-296 K and pressure 7-50 Torr ranges using absorption spectrometry. The c-(CH2)5COO was produced by the photolysis of c-(CH2)5CIBr at 213 nm in the presence of O2. We compare the measured fast c-(CH2)5COO unimolecular rate coefficient, 1998 ± 147 s-1 at 296 K, with the literature calculations for the structurally similar E-nopinone oxide formed in β-pinene ozonolysis. The kuni(c-(CH2)5COO)/2024-01-01T00:00:00Z2024 May2025-04-04T02:54:10.249Z2025-04-04T02:54:10.249ZS-EPMC113899763872774710.1021/acs.jpclett.4c00554