What is the Diffusion Tensor for Isotropic Media?

[Carl140]

Does anyone know how to write the diffusion tensor (coefficient) for a isotropic media?
It should be a matrix but I can't find it in the literature. Maybe you guys know it or can help.
Jackson doesn't have it.

Cheers

 

[Andy Resnick]

Isotropic diffusion is written as a matrix proportional to the identity matrix:

http://en.wikipedia.org/wiki/Diffusion_MRI

 

[Carl140]

Thanks Andy, I'm very sorry, I'm stupid, I'm looking for "diffusion tensor for an ANISOTROPIC media", not isotropic.

Again, sorry.

 

[Andy Resnick]

Then make the tensor not proportional to the identity matrix. Not sure what the off-diagonal coefficients correspond to, physically.