Mercier X, Carrivain O, Irimiea C, Faccinetto A, Therssen E
Université Lille, CNRS, UMR 8522 - PC2A - Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France.
Phys Chem Chem Phys. 2019 Apr 17;21(16):8282-8294. doi: 10.1039/c9cp00394k.
The soot nucleation process, defined as the transition from molecular precursors to condensed matter, is the less understood step in the whole soot formation process. The possibility that polycyclic aromatic hydrocarbon (PAH) dimers, especially those containing moderate-sized PAHs, can play a major role in soot nucleation is a very controversial issue. Although PAH dimers have often been considered as potential soot precursors, their formation is not thermodynamically favored at a typical flame temperature, their binding energies being considered too weak to allow them to survive in this environment. Hereby, we report experimental evidence supporting the existence of PAH dimers in the proximity of the soot nucleation region of a methane laminar diffusion flame that gives strong evidence for the nucleation process to be kinetically rather than thermodynamically controlled.
烟灰成核过程被定义为从分子前驱体到凝聚态物质的转变，是整个烟灰形成过程中了解较少的步骤。多环芳烃（PAH）二聚体，尤其是那些含有中等大小PAH的二聚体，在烟灰成核中发挥主要作用的可能性是一个极具争议的问题。尽管PAH二聚体常常被视为潜在的烟灰前驱体，但在典型火焰温度下其形成在热力学上并不有利，因为它们的结合能被认为太弱，以至于无法在这种环境中留存。在此，我们报告了实验证据，支持在甲烷层流扩散火焰的烟灰成核区域附近存在PAH二聚体，这为成核过程受动力学而非热力学控制提供了有力证据。
