A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling

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• 作者：Kirill Prozument ; Yury V. Suleimanov ; Beat Buesser ; James M. Oldham ; William H. Green ; Arthur G. Suits ; Robert W. Field
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2014
• 出版时间：November 6, 2014
• 年：2014
• 卷：5
• 期：21
• 页码：3641-3648
• 全文大小：364K
• ISSN：1948-7185

文摘

Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH₃CH₂ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000鈥?800 K. The branching between HNO, CH₂O, and CH₃CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH₃CH₂ONO 鈫?CH₃CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH₃CH₂ONO 鈫?CH₃CH₂O + NO. HNO is a signature of roaming in this system.

Keywords:

dynamics; kinetics; spectroscopy; roaming; chirped pulse; CPmmW; millimeter wave; microwave; Reaction Mechanism Generator, RMG; Python; RMG-Py; CHEMKIN; nitrogen chemistry; unimolecular reaction; transition state theory; branching ratio; reaction yield; molecular beam; pyrolysis; Chen nozzle; combustion; ethyl nitrite, C₂H₅ONO; methyl nitrite, CH₃ONO; nitrosyl hydride; nitroxyl; acetaldehyde; formaldehyde, H₂CO; nitric oxide