Abstract
The modes of cross‐relaxation of a double‐resonance system are discussed, and calculated for a number of simple cases. The action of the dipolar reservoirs in inhibiting the equilibration of the Zeeman reservoirs is described. The behaviour of the system may be interpreted in terms of maximisation of entropy. Numerical results are obtained for the case of double‐resonance in sodium fluoride with the Zeeman field in the (111) direction.