biostudies-literatureKao TYNational Science and Technology CouncilMinistry of Education, Taiwan9453-9461https://www.ebi.ac.uk/biostudies/studies/S-EPMC11533191biostudies-literatureUnknown128(43)A flow reactor coupled with a light-emitting diode at 286 nm, an infrared quantum-cascade laser near 11 μm, and an ultraviolet laser at 335 nm was implemented to probe the precursor CH₃CHI₂, <i>syn</i>-CH₃CHOO, and <i>anti</i>/<i>syn</i>-CH₃CHOO, respectively, in the reaction of CH₃CHI + O₂. The branching between <i>syn</i>- and <i>anti</i>-CH₃CHOO was determined to be ≈80:20 from two methods. The concentration temporal profiles of <i>anti</i>-CH₃CHOO, derived on comparison of infrared and ultraviolet profiles, yielded the rate coefficient for the self-reaction of <i>anti</i>-CH₃CHOO, <i>k</i>_self ^anti = (6 ± 2) × 10^-10 cm³ molecule^-1 s<sThe journal of physical chemistry. ARate Coefficient and Branching Ratio for the Formation of Criegee Intermediate S&lt;i&gt;yn&lt;/i&gt;-/A&lt;i&gt;nti&lt;/i&gt;-CH&lt;sub&gt;3&lt;/sub&gt;CHOO from CH&lt;sub&gt;3&lt;/sub&gt;CHI + O&lt;sub&gt;2&lt;/sub&gt; and the Self-Reaction of S&lt;i&gt;yn&lt;/i&gt;-/A&lt;i&gt;nti&lt;/i&gt;-CH&lt;sub&gt;3&lt;/sub&gt;CHOO Determined with Simultaneous IR/UV Probes.PMC11533191112-2634-F-009-026112-2639-M-A49-001-ASPLee YPKao TYChung CAfalseRate Coefficient and Branching Ratio for the Formation of Criegee Intermediate S&lt;i&gt;yn&lt;/i&gt;-/A&lt;i&gt;nti&lt;/i&gt;-CH&lt;sub&gt;3&lt;/sub&gt;CHOO from CH&lt;sub&gt;3&lt;/sub&gt;CHI + O&lt;sub&gt;2&lt;/sub&gt; and the Self-Reaction of S&lt;i&gt;yn&lt;/i&gt;-/A&lt;i&gt;nti&lt;/i&gt;-CH&lt;sub&gt;3&lt;/sub&gt;CHOO Determined with Simultaneous IR/UV Probes.A flow reactor coupled with a light-emitting diode at 286 nm, an infrared quantum-cascade laser near 11 μm, and an ultraviolet laser at 335 nm was implemented to probe the precursor CH₃CHI₂, <i>syn</i>-CH₃CHOO, and <i>anti</i>/<i>syn</i>-CH₃CHOO, respectively, in the reaction of CH₃CHI + O₂. The branching between <i>syn</i>- and <i>anti</i>-CH₃CHOO was determined to be ≈80:20 from two methods. The concentration temporal profiles of <i>anti</i>-CH₃CHOO, derived on comparison of infrared and ultraviolet profiles, yielded the rate coefficient for the self-reaction of <i>anti</i>-CH₃CHOO, <i>k</i>_self ^anti = (6 ± 2) × 10^-10 cm³ molecule^-1 s<s2024-01-01T00:00:00Z2024 Oct2025-04-26T17:07:17.919Z2025-04-06T15:22:40.847ZS-EPMC115331913942726010.1021/acs.jpca.4c06588