Diffusion of nanoparticles in a rarefied gas

It is suggested to describe the diffusion of nanoparticles in rarefied gases in terms of the kinetic theory. For this purpose, the potential of interaction between a carrier gas molecule and a dispersed particle is constructed by summing the interactions of the given gas molecule with all atoms (molecules) of the dispersed particle. With this potential, a formula for the diffusion coefficient of the dispersed nanoparticle is derived. The dependence of the diffusion coefficient on the radius and temperature is studied. Analytical results are compared with experimental data. The well-known experimental Cunningham-Millikan correlation is shown to apply only in the range of near-room temperatures, for which the parameters of this correlation were determined.