Processes involving clusters and small particles in a buffer gas

Processes involving clusters and small particles are considered from the standpoint of interaction of clusters or small particles with atomic particles of a buffer gas. Two opposite interaction regimes are the kinetic (dynamic) and diffusion (hydrodynamic) ones, so that in the first case collisions of a gas atom with a cluster or small particle are analogous to collisions of two atomic particles in a gas, whereas in the diffusion regime a cluster or a small particle strongly interacts simultaneously with many atoms. Criteria and parameters of processes for the kinetic and diffusion regimes are given for transport phenomena in gases involving clusters or small particles, cluster charging in an ionized gas and particle combustion, and also nucleation processes including cluster growth as a result of atom attachment to a growing cluster, the coagulation and coalescence processes.