The Criegee intermediates, carbonyl oxides produced in ozonolysis of unsaturated hydrocarbons, play important roles in atmospheric chemistry. The two conformers of CH₃CHOO exhibit distinct reactivity toward several atmospheric species, but a distinct conformer-specific probe is challenging because ultraviolet and infrared absorption bands of syn- and anti-CH₃CHOO overlap at low-resolution. Employing a quantum-cascade laser and a Herriott cell, we recorded the O–O stretching bands of CH₂OO and syn-CH₃CHOO in region 880–932 cm^–1 at resolution 0.0015 cm^–1. In addition to completely resolved vibration–rotational lines of CH₂OO extending over 50 cm^–1, some spectral lines associated with hot bands were identified. Spectral lines solely due to syn-CH₃CHOO were also identified. Probing these lines, we determined the rate coefficient for the self-reaction of syn-CH₃CHOO to be k_self = (1.6 ± _0.6^0.5) × 10^–10 cm³ molecule^–1 s^–1, about twice that of CH₂OO.

中文翻译：

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Criegee通过量子级联激光器通过高分辨率红外光谱鉴定syn- CH ₃ CHOO和CH ₂ OO中间体的识别和自反应动力学

Criegee中间体，即不饱和烃的臭氧分解过程中产生的羰基氧化物，在大气化学中起着重要作用。CH ₃ CHOO的两个构象异构体对几种大气物种表现出不同的反应性，但是不同的构象异构体特异性探针却具有挑战性，因为syn-和抗-CH ₃ CHOO的紫外和红外吸收带在低分辨率下重叠。利用量子级联激光器和Herriott细胞，我们记录了CH ₂ OO和syn- CH ₃ CHOO的O–O伸缩带，其分辨率为0.0015 cm ^–1，位于880–932 cm ^–1区域。。除了CH ₂ OO的完全旋转的旋转旋转线（延伸超过50 cm ^{–1）之外}，还识别出一些与热带相关的光谱线。还确定了仅由于syn CH ₃ CHOO引起的光谱线。探测这些线，我们确定syn - CH ₃ CHOO的自反应速率系数为k _self =（1.6± _0.6 ^0.5）×10 ^–10 cm ³分子^–1 s ^–1，约为CH _2的两倍哦