This blog is based on the article in Applied Science and Convergence Technology 26 (5): 95-109 (2017) R Grinham and A Chew.
There are several contributions to the gas load of a system. At pressures below ~0.1 mbar, the most dominant is often ‘outgassing’. Outgassing is the result of desorption of previously adsorbed molecules, bulk diffusion, permeation and vapourisation. Adsorption occurs via two main processes, physisorption and chemisorption, and can be described using five (or six) classifying isotherms.