  Dinuclear systems that occur in the post-saddle to scission stage in nuclear
fission process are special transient formations. The diabatic evolution at
this stage is studied using the methods of non-equilibrium thermodynamics. A
novel explanation for the emergence of intrinsic rotational modes that occur in
such a dinucleus is developed by identifying these modes together as an open
subsystem that exchanges matter and energy with its environment. The
environment consists of all remaining degrees of freedom of the dinucleus, and
a weak coupling of the subsystem to this environment facilitates a diabatic
energy exchange. Under appropriate non-equilibrium conditions, the available
energy is coupled to the work needed for the emergence of self organizing
rotational modes. This comes at the expense of increasing microscopic disorder
in the form of intrinsic excitations in the prefragments. A simple formalism is
presented such that the magnitudes of relevant energy flow through the
subsystem are obtained in terms of entropy production rate, entropy expulsion
rate and net rate of change of entropy in sub-units of $MeV zs^{-1} K^{-1}$.
