Infrared spectral identification of the Criegee intermediate (CH3)2COO

Yi Ying Wang; Chao Yu Chung; Yuan-Pern Lee

doi:10.1063/1.4964658

Infrared spectral identification of the Criegee intermediate (CH₃)₂COO

Yi Ying Wang, Chao Yu Chung, Yuan-Pern Lee^*

^*Corresponding author for this work

Department of Applied Chemistry

Research output: Contribution to journal › Article › peer-review

26 Scopus citations

Abstract

Criegee intermediates are carbonyl oxides that play critical roles in the ozonolysis of alkenes in the atmosphere. So far, the infrared spectra of only the simplest Criegee intermediates CH₂OO and CH₃CHOO are reported. We report the transient infrared spectrum of the next member (CH₃)₂COO, produced from ultraviolet irradiation of a mixture of (CH₃)₂CI₂ + O₂ in a flow reactor and detected with a step-scan Fourier-transform spectrometer. The four observed bands near 1424, 1368, 1040, and 887.4 cm^-1 provide definitive identification of (CH₃)₂COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations; contributions of the hot bands from excited states of the low-lying torsional modes are significant. The rapid decay yields an estimate of the rate coefficient ∼1.6 × 10^-10 cm³ molecule^-1 s^-1 for the self-reaction of (CH₃)₂COO. The direct IR detection of (CH₃)₂COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.

Original language	English
Article number	154303
Number of pages	6
Journal	Journal of Chemical Physics
Volume	145
Issue number	15
DOIs	https://doi.org/10.1063/1.4964658
State	Published - 21 Oct 2016

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title = "Infrared spectral identification of the Criegee intermediate (CH3)2COO",

abstract = "Criegee intermediates are carbonyl oxides that play critical roles in the ozonolysis of alkenes in the atmosphere. So far, the infrared spectra of only the simplest Criegee intermediates CH2OO and CH3CHOO are reported. We report the transient infrared spectrum of the next member (CH3)2COO, produced from ultraviolet irradiation of a mixture of (CH3)2CI2 + O2 in a flow reactor and detected with a step-scan Fourier-transform spectrometer. The four observed bands near 1424, 1368, 1040, and 887.4 cm-1 provide definitive identification of (CH3)2COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations; contributions of the hot bands from excited states of the low-lying torsional modes are significant. The rapid decay yields an estimate of the rate coefficient ∼1.6 × 10-10 cm3 molecule-1 s-1 for the self-reaction of (CH3)2COO. The direct IR detection of (CH3)2COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.",

author = "Wang, {Yi Ying} and Chung, {Chao Yu} and Yuan-Pern Lee",

note = "Publisher Copyright: {\textcopyright} 2016 Author(s).",

year = "2016",

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doi = "10.1063/1.4964658",

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AU - Wang, Yi Ying

AU - Chung, Chao Yu

AU - Lee, Yuan-Pern

PY - 2016/10/21

Y1 - 2016/10/21

N2 - Criegee intermediates are carbonyl oxides that play critical roles in the ozonolysis of alkenes in the atmosphere. So far, the infrared spectra of only the simplest Criegee intermediates CH2OO and CH3CHOO are reported. We report the transient infrared spectrum of the next member (CH3)2COO, produced from ultraviolet irradiation of a mixture of (CH3)2CI2 + O2 in a flow reactor and detected with a step-scan Fourier-transform spectrometer. The four observed bands near 1424, 1368, 1040, and 887.4 cm-1 provide definitive identification of (CH3)2COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations; contributions of the hot bands from excited states of the low-lying torsional modes are significant. The rapid decay yields an estimate of the rate coefficient ∼1.6 × 10-10 cm3 molecule-1 s-1 for the self-reaction of (CH3)2COO. The direct IR detection of (CH3)2COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.

AB - Criegee intermediates are carbonyl oxides that play critical roles in the ozonolysis of alkenes in the atmosphere. So far, the infrared spectra of only the simplest Criegee intermediates CH2OO and CH3CHOO are reported. We report the transient infrared spectrum of the next member (CH3)2COO, produced from ultraviolet irradiation of a mixture of (CH3)2CI2 + O2 in a flow reactor and detected with a step-scan Fourier-transform spectrometer. The four observed bands near 1424, 1368, 1040, and 887.4 cm-1 provide definitive identification of (CH3)2COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations; contributions of the hot bands from excited states of the low-lying torsional modes are significant. The rapid decay yields an estimate of the rate coefficient ∼1.6 × 10-10 cm3 molecule-1 s-1 for the self-reaction of (CH3)2COO. The direct IR detection of (CH3)2COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.

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M1 - 154303

ER -

Infrared spectral identification of the Criegee intermediate (CH₃)₂COO

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