利用步進式掃描傅氏轉換時域解析紅外光譜法研究Criegee中間體(CH3)2COO之紅外吸收光譜

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 provide definitive identification of (CH3)2COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations. The rapid decay yields an estimate of the rate coefficient for self-reaction, ~1.610−10 cm3 molecule−1 s−1. The direct IR detection of (CH3)2COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.

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 provide definitive identification of (CH3)2COO. The observed vibrational wavenumbers and rotational contours agree with those predicted with quantum-chemical calculations. The rapid decay yields an estimate of the rate coefficient for self-reaction, ~1.610−10 cm3 molecule−1 s−1. The direct IR detection of (CH3)2COO should prove useful for field measurements and laboratory investigations of related Criegee mechanism.