Atomic force microscopy images of molecules found in soot

High-resolution imaging has revealed the structural make-up of soot particles. Credit: F. Schulz et al./Proc. Combust. Inst.

Nanoscience and technology

First portrait of a soot molecule

Imaging techniques reveal honeycomb structure at the heart of a soot-particle precursor.

Soot’s molecular building-blocks have been glimpsed for the first time.

Soot particles are harmful to humans and the environment. Researchers agree that soot is composed of carbon-based molecules called polycyclic aromatic hydrocarbons, but uncertainty remains about how these molecules look and how they cluster into soot particles.

A team led by Leo Gross at IBM Research–Zurich in Switzerland and Andrea D’Anna at the University of Naples Federico II in Italy examined soot precursors using techniques such as atomic-force microscopy, which produces an ultra-high-resolution topographic map of a sample.

The analysis revealed that many soot precursors contain six-sided chemical structures that look like the cells of a honeycomb. The team also confirmed a previous prediction that soot precursors contain unpaired electrons.

Knowledge about the appearance of soot precursors could help scientists to understand, and potentially prevent, their formation.