Nucleation and structure of soot particles: Investigating the role of curved aromatics and ions

A complete description of carbonaceous particulate behaviour in combustion processes requires detailed knowledge of the gas-to-solid transition of hydrocarbon molecules to form soot particles. This process is poorly understood due to low species concentrations, short time frame, and small length scales, which limit experimental measurements. Molecular modelling tools are not restricted by these conditions and therefore provide valuable insight into the behaviour of soot nanoparticles. It is known that curved polycyclic aromatic hydrocarbons (cPAHs) possess significant dipole moments and are found within flames[1]. Recent work suggests that long-range interactions between these curved species and chemi-ions may be important to the soot formation mechanism[2]. This work explores the impact of ion-cPAH interactions in stabilising nascent soot particles and works towards the development of a heterogeneous nucleation model for these species. Molecular dynamics simulations provide information on homogeneous and ion-induced heterogeneous nucleation of cPAHs. The formation dynamics and internal particle structures are explored across a range of temperatures. These results provide insight into how the interactions between cPAHs and ions affect the formation and structure of soot nanoparticles and provide valuable information towards expanding current soot models.

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