Diffusivities of low‐volatility species in light gases

Abstract

Abstract Gas‐phase diffusivities for high boiling point organics in common gases are determined by evaporating a single submicron aerosol droplet of the organic species, while it is suspended in an electric field in the path of a polarized laser beam. The droplet size is measured as a function of time by using Mie theory to determine the size from the light scattering data of intensity versus angle. In addition to diffusivities, the Lennard‐Jones molecular interaction potential parameter, ϵ ii , and the collision diameter σ ii , are found, by applying the molecular theory of gases to interpret the evaporation rate data. Results are compared with available empirical and semi‐theoretical correlations for diffusivities and Lennard‐Jones parameters. The low vapor pressure organics used here are dioctyl phthalate (DOP), dibutyl sebacate (DBS) and dibutyl phthalate (DBP), and the carrier gases are helium, nitrogen and carbon dioxide.