Faccinetto Alessandro, Irimiea Cornelia, Minutolo Patrizia, Commodo Mario, D'Anna Andrea, Nuns Nicolas, Carpentier Yvain, Pirim Claire, Desgroux Pascale, Focsa Cristian, Mercier Xavier
Univ. Lille, CNRS, UMR 8522, PC2A, F-59000, Lille, France.
DMPE, ONERA, Univ. Paris Saclay, F-91123, Palaiseau, France.
Commun Chem. 2020 Aug 11;3(1):112. doi: 10.1038/s42004-020-00357-2.
The role of polycyclic aromatic hydrocarbons (PAHs) in the formation of nascent soot particles in flames is well established and yet the detailed mechanisms are still not fully understood. Here we provide experimental evidence of the occurrence of dimerization of PAHs in the gas phase before soot formation in a laminar diffusion methane flame, supporting the hypothesis of stabilization of dimers through the formation of covalent bonds. The main findings of this work derive from the comparative chemical analysis of samples extracted from the gas to soot transition region of a laminar diffusion methane flame, and highlight two different groups of hydrocarbons that coexist in the same mass range, but show distinctly different behavior when processed with statistical analysis. In particular, the identified hydrocarbons are small-to-moderate size PAHs (first group) and their homo- and heterodimers stabilized by the formation of covalent bonds (second group).
多环芳烃（PAHs）在火焰中新生烟灰颗粒形成过程中的作用已得到充分证实，但其详细机制仍未完全理解。在此，我们提供了实验证据，证明在层流扩散甲烷火焰中形成烟灰之前，气相中存在PAHs二聚化现象，支持了通过共价键形成使二聚体稳定的假设。这项工作的主要发现源于对从层流扩散甲烷火焰的气体到烟灰过渡区域提取的样品进行的比较化学分析，并突出了两组共存于相同质量范围内的不同烃类，但在用统计分析处理时表现出明显不同的行为。特别是，鉴定出的烃类是中小尺寸的PAHs（第一组）及其通过共价键形成而稳定的同二聚体和异二聚体（第二组）。
