- Spin-Lattice Relaxation Time

Spin-Lattice Relaxation Time

Definition: (Lattice) The material in which the nuclear magnets are embedded is generally referred to as the lattice, whether it be solid, liquid or gas.

Let us now consider an assembly of identical spin-1/2 nuclei in the presence of a steady magnetic field $H_{_{0}}$. Assume that there is only weak coupling between the nuclear spins. This assumption allows us to consider that the spin energy levels of the assembly are the same as that for a single spin. Although we assume weak coupling between the spins the coupling must not be zero. That is, the weak coupling between the spins must at least be sufficient enough to bring about thermal equilibrium between the spins. Furthermore, suppose that the interaction between the nuclear spins and the lattice is even smaller than the interaction between spins. This means that, apart from the feeble paramagnetism produced by the nuclei, the material concerned must be diamagnetic (water is diamagnetic).