Soot particles are seen everywhere from city centres to the Alps. There’s ongoing debate on the nature and dynamic evolution of these particles in atmosphere. Soot are light-absorbing, chemically and morphologically complex particles that contribute to air pollution and can have negative health effects. Soot particles are emitted from flames and engines and are highly regional pollutants.

Inhaled soot particle are known to accumulate in body and can lead to cardiovascular diseases. But a mechanistic understanding of the health effects is still lacking says Joel Corbin, a PhD Candidate at the Institute for Atmospheric and Climate Science in ETH Zurich, Switzerland. Particle properties like its size, shape, surface chemistry, and chemical composition can all influence the health effects of soot inhalation.

In this latest SOCAAR seminar Corbin presented his research on characterization of soot particles. Traditionally, particles are collected on TEM grids and the sizes are measured visually. The particles can be rotated using offline electron tomography to get what particle looks like in three-dimensions. But this is a non-statistical process that is very time consuming. Alternatively, the particle size and number of particles can be measured by online techniques.

Corbin used online techniques such as aerosol mass spectrometry to conduct real-time analysis of the soot particle evolution. He was able to predict particle characteristics based on the size measurements. The chemical composition of the soot particles is found to consist of three components: a grapheme-like core consisting of black carbon; oxidized groups at the surface of the graphene core; and condensation of organic materials on top of the particle.