Why soot forms

This discovery provides a fundamentally new insight into the physics of the high-temperature inception of small carbonaceous particles. Johansson Sandia National Laboratories okjohans gmail. Michelsen Sandia National Laboratories hamiche sandia. Johansson, M. Head-Gordon, P. Schrader, K. Wilson, and H. Michelsen, " Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth.

Science podcast starts at 9 minutes in : Why were chemists baffled by soot for so long? Blazowski, Combust. Gaydon, H. Chapman and Hall, London Gaydon, G.

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What is Soot? September 12, Soot Pollution [Online]. It leads to tens of thousands of deaths in the U. In the atmospheric emissions of soot are known as black carbon. She said soot formation turns out to be very different from the typical process of gas molecules condensing into a particle, instead, requiring fast chemical reactions rather than condensation.

The solution also can apply to other high-temperature conditions, such as interstellar space, where large quantities of carbon-dust particles are formed, she said. This groundbreaking work was published in a Science magazine paper, "Resonance-stabilized hydrocarbon-chain reactions may explain soot inception and growth. Soot is formed during the combustion of hydrocarbon fuels, such as oil, natural gas, and wood.

Although it has detrimental health and environmental effects, soot is extremely important to many industrial processes, such as boiler performance, glass production, and carbon-black generation for rubber-product reinforcement and pigments.

Despite the ubiquity and importance of soot, the basic chemistry explaining why the molecules in a flame stick together at high temperatures and form particles has remained a scientific puzzle until now, said Michelsen. In its final form, soot is a solid very similar to graphite, but it is initially formed from gaseous hydrocarbons. Experimental evidence indicates that it transitions from a gas to a liquid before it becomes a solid.

Scientists have been trying for decades to explain that transition. Cooling it further will turn it into ice, the solid phase of water. Soot is different," said Michelsen.