A novel ultra-high vacuum diffusion setup to study Knudsen diffusion

Abstract

A new experimental technique has been developed for studies of transport diffusion in the Knudsen regime. At atmospheric pressure, the Knudsen regime is prevalent for gas diffusion in mesoporous materials. A unique, specially designed Ultra-High Vacuum Diffusion Setup has been built that allows the generation of high Knudsen numbers at macroscopic scales by employing ultra-high vacuum conditions. The diffusion channel of the setup can, therefore, act as a magnified nanopore model to help study the impact of different pore geometries on Knudsen diffusion. Pore channels with varying pore length, pore cross-sectional shape, and pore diameter were realised and tested with this setup. The results obtained using this experimental technique can be compared with analytical and computational results to gain insight into diffusion in nanoporous materials.