Influence of Onion-like Carbonaceous Particles on the Aggregation Process of Hydrocarbons

Molecular dynamics
simulations are performed to characterize the
nucleation behavior of organic compounds in the gas phase. Six basic
molecular species are consideredethylene, propylene, toluene,
styrene, ethylbenzene, and para-xylenein
interaction with onion-like carbon nanostructures that model soot
nanoparticles (NPs) at room temperature. We identify a shell-to-island
aggregation process during the physisorption of aromatic molecules
on the soot surface: The molecules tend to first cover the NP in a
shell, on top of which additional adsorbates form island-shaped aggregates.
We present results for the binding energy, suggesting that the NPs
lead to the formation of more stable molecular aggregates in comparison
with the pure gas phase. Our findings describe a plausible microscopic
mechanism for the active role of soot in the formation and growth
of organic particulate matter.