Sub-2 nm particle measurement in high-temperature aerosol reactors: a review

Aerosol science and technology enable continual advances in material synthesis and atmospheric pollutant control. Among these advances, one important frontier is characterizing the initial stages of particle formation by real-time measurement of particles below 2 nm in size. Sub-2 nm particles play important roles by acting as seeds for particle growth, ultimately determining the final properties of the generated particles. Tailoring nanoparticle properties requires a thorough understanding and precise control of the particle formation processes, which in turn requires characterizing nanoparticle formation from the initial stages. This article reviews current aerosol instruments measuring the size, concentration, and chemical composition of sub-2 nm particles. Recent measurements of sub-2 nm particles generated from different types of high-temperature aerosol reactors are also summarized.