New Particle Formation and Growth: Creating a New Atmospheric Phase Interface

Abstract This chapter discusses the phenomena that drive atmospheric new particle formation and growth from condensable vapors. The chapter begins with a general introduction to atmospheric gas-to-particle conversion and the participating compounds and proceeds to discuss the detailed chemistry and physics related to different stages of the process. The two main sections focus on the initial formation of molecular clusters of 1–3 nm from gas-phase molecules and on the further growth of these nanoparticles to sizes of tens of nanometers at which they affect climate and human health. The sections present the main experimental and theoretical tools used to study the initial molecular-scale clustering phenomena and the condensational growth of macroscopic particles. The discussion covers thermodynamics related to clustering and condensation-driven growth, including particle surface phenomena and particle-phase processes, as well as kinetic aspects related to the dynamics of a population of interacting particles.