Carl Sagan famously said, “…to make an apple pie, you have to make a universe.” It turns out that sometimes, to understand the chemistry of the universe you have to understand the pollutants of the planet Earth.

Combustion processes generate complex molecules called polycyclic aromatic hydrocarbons (PAHs). These large collections of atoms are part of soot and not entirely healthy to breathe. They also form naturally in massive molecular clouds in some of the colder and denser parts of space. According to Hanfeng Jin: During combustion, soot formation can be significant in a reaction environment that is deficient in radicals. Likewise, the temperature in the interstellar medium is too low to maintain a sufficient radical pool, and radicals produced by high-energy photons in the galaxy are rare.

In a new paper in the Journal of Physical Chemistry Letters, Jin leads a team that numerically models how PAHs form and the role of a specific compound called butadiyne. They realized that this molecule, which forms in burning organics like oil, also forms in places like Saturn’s moon Titan. By understanding how the molecules form in such different environments, they are working toward changing what comes out of various industrial processes on Earth so that less harmful molecules result, and we can all breathe a little bit easier.

More Information

Kaust press release

“Continuous Butadiyne Addition to Propargyl: A Radical-Efficient Pathway for Polycyclic Aromatic Hydrocarbons,” Hanfeng Jin et al., 2021 August 19, The Journal of Physical Chemistry Letters

“First aromatic ring formation by the radical-chain reaction of vinylacetylene and propargyl,” Hanfeng Jin et al., 2020 December 1, Combustion and Flame