How can I think of rotational diffusion inverse seconds?

[Steve Drake]

When thinking of a spherical shaped particle moving about under Brownian motion, one describes its motion by Diffusion. The units being $$\frac{m^2}{s}$$ I can understand this physically as a distance it will travel from a certain point in space averaged over x-y and z direction.
Now rotational diffusion on the other hand has units of inverse seconds $$\frac{1}{s}$$ I cannot think of a way to visualize that? For e.g. a rod shaped particle, what does a
$$D_r = 10\, s^{-1}$$ as opposed to say a $$D_r = 100\, s^{-1}$$ mean? How can I visualize this like I can with a sphere moving an actual distance?
Thanks

 

[D H]

Think of rotational diffusion as having units radian²/s instead of 1/s.

 

[Steve Drake]

Hi, Thanks

That makes a big more sense...

So in a geometrical sense... if a rod's center of mass with fixed in a liquid somehow, but it could still rotate around that point, does this mean the distance its ends would 'trace' out on a hypothetical sphere in 1 second would equal eg 40 radians?... I am still a bit confused thanks