What is pre-exponential factor for diffusion, because i have a problem with this equation.

Question

D=D0*exp[-Ea/R*T]
where D=2*10^-13
Ea=2.9*10^-19 joules/atom
T=1009 K
How to find the pre-exponential ?

Answer 1

What you have is just D = D0*x where x is all that exponential stuff.

So, D0 = D/x

Of course, R is not specified. If it's R you are looking for, then just work it out like this:

exp[-Ea/R*T] = D/D0
-Ea/R*T = ln(D/D0)
R = -Ea*T/ln(D/D0)

Answer 2

Yeah, R is a constant.The gas constant.
But i can't calculate this D0.