Bond cleavage

Catalysis

Chemical physics

Photochemistry

Chromatography

Nuclear magnetic resonance

Atomic physics

Electron paramagnetic resonance

Chain reaction

Physics

Organic chemistry

Cyclopentadiene

Mass spectrum

Soot

Resonance (particle physics)

Combustion

Computational chemistry

Radical

Mass spectrometry

Chemistry

Hydrocarbon

Science

A radical route to soot The chemical origin of soot is a persistent puzzle. It is clear that small hydrocarbon fragments formed in flames must aggregate into larger particles, but the initial driving force for aggregation remains a mystery. Johansson et al. combined theory and mass spectrometry to suggest a solution based on resonance-stabilized radicals (see the Perspective by Thomson and Mitra). Aromatics such as cyclopentadiene have a characteristically weak C–H bond because their cleavage produces radicals with extended spans of π-electron conjugation. Clusters thus build up through successive coupling reactions that extend conjugation in stabilized radicals of larger and larger size. Science , this issue p. 997 ; see also p. 978

Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth