Diffusion parameters can be measured straightforwardly by applying an
'activity' difference across a flat layer. Then Fick's first law
applies:
J = D
Δc
or J = ℘
ΔP
L
L
where J is flux, D diffusion coefficient, c concentration, ℘ permeability,
P partial pressure, L layer thickness and the Δ indicates a difference.
All these terms are explained in the topic choices.
