Characterization of nanoparticles
The characterization of nanoparticles is a branch of nanometrology that deals with the characterization, or measurement, of the physical and chemical properties of nanoparticles. Nanoparticles measure less than 100 nanometers in at least one of their external dimensions, and are often engineered for their unique properties.
Source: Wikipedia — Characterization of nanoparticles (CC BY-SA 4.0)