How do scientists use scattering measurements to track nanoparticle aggregation?

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Gold and palladium alloy nanoparticles — nanoparticle Image showing nanoparticles of an alloy of gold (yellow) and palladium (blue) on an acid-treated carbon support (gray). These particles were employed as catalysts for the formation of hydrogen peroxide from hydrogen (white) and oxygen (red).

Scientists track nanoparticle aggregation using indirect techniques known as small-angle scattering, specifically small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS).1

These methods function by analyzing the radiation scattered or diffracted by nanoparticles. Unlike direct imaging techniques that are limited to observing a few particles at a time, scattering measurements allow researchers to simultaneously sample and average data from a vast number of particles.1

This approach is particularly effective for monitoring aggregation behavior over time because it often requires minimal sample preparation and can be used in complex environments. For instance, researchers have utilized SANS to study nanoparticles in turbid substances like raw sewage; because neutrons can penetrate the medium, they scatter strongly off the particles, allowing scientists to track how the nanoparticles aggregate as conditions change.1