Abstract Understanding the multi-channel dynamics of O(1D) reactions with unsaturated hydrocarbon molecules in low temperature reaction kinetics is critically important in stratospheric chemistry, plasma chemistry, plasma assisted fuel reforming, materials synthesis, and plasma assisted combustion. A photolysis flow reactor coupled with highly selective mid-infrared Faraday Rotation Spectroscopy (FRS) and direct ultraviolet-infrared (UV-IR) absorption spectroscopy (DAS) techniques was developed for the first time to study the multi-channel dynamics of excited singlet oxygen atom O(1D) reactions with C2H2 and the kinetics of subsequent reactions. Time-resolved species concentrations of OH, HO2 and H2O were obtained and used to develop a validated kinetic model of O(1D) reactions with C2H2. The branching ratios of O(1D) reaction with C2H2 and subsequent HO2 kinetics were also quantified. It is found that, contrary to O(1D) reactions with saturated alkanes, OH formation via direct H abstraction by O(1D) is negligible. The results revealed that two chain-branching and propagation reactions via direct O(1D) insertion are the major pathways for radical production. The present study clearly demonstrated the advantage of radical detection and kinetic studies using FRS in the effective suppression of absorption interference from non-paramagnetic hydrocarbons.

中文翻译：

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激发单线态氧原子O(1D)与乙炔反应动力学研究

摘要 了解低温反应动力学中 O(1D) 与不饱和烃分子反应的多通道动力学对于平流层化学、等离子体化学、等离子体辅助燃料重整、材料合成和等离子体辅助燃烧至关重要。首次开发了结合高选择性中红外法拉第旋转光谱 (FRS) 和直接紫外-红外 (UV-IR) 吸收光谱 (DAS) 技术的光解流动反应器来研究激发单线态氧的多通道动力学原子 O(1D) 与 C2H2 的反应以及后续反应的动力学。获得了 OH、HO2 和 H2O 的时间分辨物质浓度，并用于开发 O(1D) 与 C2H2 反应的经过验证的动力学模型。O(1D) 与 C2H2 反应的支化率和随后的 HO2 动力学也被量化。发现与 O(1D) 与饱和烷烃的反应相反，通过 O(1D) 直接提取 H 形成的 OH 可以忽略不计。结果表明，通过直接 O(1D) 插入的两个链分支和传播反应是自由基产生的主要途径。本研究清楚地证明了使用 FRS 进行自由基检测和动力学研究在有效抑制非顺磁性碳氢化合物吸收干扰方面的优势。结果表明，通过直接 O(1D) 插入的两个链分支和传播反应是自由基产生的主要途径。本研究清楚地证明了使用 FRS 进行自由基检测和动力学研究在有效抑制非顺磁性碳氢化合物吸收干扰方面的优势。结果表明，通过直接 O(1D) 插入的两个链分支和传播反应是自由基产生的主要途径。本研究清楚地证明了使用 FRS 进行自由基检测和动力学研究在有效抑制非顺磁性碳氢化合物吸收干扰方面的优势。