用时间分辨傅里叶变换光谱法探测 CH3OSO 的红外吸收。

Infrared absorption of CH3OSO detected with time-resolved Fourier-transform spectroscopy.

机构信息

Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.

出版信息

J Chem Phys. 2011 Mar 7;134(9):094304. doi: 10.1063/1.3556817.

DOI:10.1063/1.3556817

PMID:21384966

Abstract

A step-scan Fourier-transform spectrometer coupled with a multipass absorption cell was employed to detect temporally resolved infrared absorption spectra of CH(3)OSO produced upon irradiation of a flowing gaseous mixture of CH(3)OS(O)Cl in N(2) or CO(2) at 248 nm. Two intense transient features with origins near 1152 and 994 cm(-1) are assigned to syn-CH(3)OSO; the former is attributed to overlapping bands at 1154 ± 3 and 1151 ± 3 cm(-1), assigned to the S=O stretching mixed with CH(3) rocking (ν(8)) and the S=O stretching mixed with CH(3) wagging (ν(9)) modes, respectively, and the latter to the C-O stretching (ν(10)) mode at 994 ± 6 cm(-1). Two weak bands at 2991 ± 6 and 2956 ± 3 cm(-1) are assigned as the CH(3) antisymmetric stretching (ν(2)) and symmetric stretching (ν(3)) modes, respectively. Observed vibrational transition wavenumbers agree satisfactorily with those predicted with quantum-chemical calculations at level B3P86∕aug-cc-pVTZ. Based on rotational parameters predicted at that level, the simulated rotational contours of these bands agree satisfactorily with experimental results. The simulation indicates that the S=O stretching mode of anti-CH(3)OSO near 1164 cm(-1) likely makes a small contribution to the observed band near 1152 cm(-1). A simple kinetic model of self-reaction is employed to account for the decay of CH(3)OSO and yields a second-order rate coefficient k=(4 ± 2)×10(-10) cm(3)molecule(-1)s(-1).

摘要

采用分步扫描傅里叶变换光谱仪结合多通吸收池，检测了在 248nm 激光辐照下，CH 3 OS(O)Cl 在 N 2 或 CO 2 中流动气体混合物时生成的 CH 3 OS 自由基的瞬态红外吸收光谱。两个强度较大的瞬态特征起源于 1152 和 994cm -1 ，分别归属于 syn-CH 3 OS ；前者归因于重叠的 S=O 伸缩与 CH 3 摇摆（ν(9)）混合（1154±3cm -1 ）和 S=O 伸缩与 CH 3 摇摆（ν(9)）混合（1151±3cm -1 ），后者归因于 C-O 伸缩（ν(10)）模式在 994±6cm -1 。两个较弱的谱带位于 2991±6 和 2956±3cm -1 ，分别归属于 CH 3 反对称伸缩（ν(2)）和对称伸缩（ν(3)）模式。观察到的振动跃迁波数与 B3P86∕aug-cc-pVTZ 水平的量子化学计算预测值吻合较好。基于该水平预测的旋转参数，这些谱带的模拟旋转轮廓与实验结果吻合较好。模拟表明，反式-CH 3 OS 中的 S=O 伸缩模式在 1164cm -1 附近可能对 1152cm -1 附近的观察到的谱带有较小的贡献。采用简单的自反应动力学模型来解释 CH 3 OS 自由基的衰减，得到二级速率系数 k = (4 ± 2)×10 -10 cm 3 molecule -1 s -1 。