ortho-Benzyne, a Kekulé-type biradical is considered to be a key intermediate in the formation of polycyclic aromatic hydrocarbons (PAH) and soot. In the present work we study the ortho-benzyne self-reactions in a hot microreactor and identify the high-temperature products by IR/UV spectroscopy and by photoion mass-selected threshold photoelectron spectroscopy (ms-TPES) in a free jet. Ms-TPES confirms formation of ortho-benzyne as generated from benzocyclobutenedione, as well as benzene, biphenylene, diacetylene, and acetylene, originating from the reaction o-C₆H₄ → HCC–CCH + C₂H₂, and CH₃. PAH molecules like naphthalene, 2-ethynylnaphthalene, fluorene, phenanthrene, and triphenylene are identified based on their IR/UV spectra. By comparison with recent computations their formation starting from o-benzyne can be readily understood and supports the importance of the biradical addition (1,4-cycloaddition followed by fragmentation) pathway to PAH molecules, recently proposed by Comandini et al.

中文翻译：

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红外和光电子能谱研究高温下邻苯甲酸的自反应

邻苯并炔，一种Kekulé型双自由基被认为是形成多环芳烃（PAH）和烟灰的关键中间体。在目前的工作中，我们研究了在热微反应器中的邻-苯甲醛自反应，并通过IR / UV光谱法和自由射流中通过离子选择质量的阈值光电子能谱法（ms-TPES）鉴定了高温产物。Ms-TPES证实了由苯并环丁烯二酮以及苯，联苯，二乙炔和乙炔生成的邻-苯甲酰，其源自反应oC ₆ H ₄ →HCC–CCH + C ₂ H ₂和CH ₃。根据PAH分子的IR / UV光谱对其进行鉴定，例如萘，2-乙炔基萘，芴，菲和联苯。通过与最近的计算相比较，可以很容易地理解它们从邻-苄基开始的形成，并支持了Comandini等人最近提出的向PAH分子的双自由基加成（1，4-环加成然后断裂）途径的重要性。