Kinetic formulation of irreversible evolution of the two-nucleus spin systems

The time irreversible evolution of the two-nucleus spin systems interacting with a magnetic field is analyzed in the framework of the subdynamics theory. The spin systems are determined by the H(1) and C(13) nuclei. The investigation is based on the complex spectral representation of the Liouvillian which gives a rigorous description of irreversibility. The evolution of the density matrix is analyzed for the short and long time regions. Quantum Zeno effect is discussed.