diffusion in gas phase
So referring to the diffusion flux of (3a) we can represent it as: (3b). (4b). The
diffusion coefficient is kT times the mobility coefficient. The consequence of Ficks
first law is the expression for the flux repeated below. Ficks 2nd law then states:
Upon dividing with and taking the limit one gets: The response to an impulse at x
= 0 ...