Nuclear Relaxation Processes of a Nonequivalent Two-Spin System

Nuclear magnetic relaxation of a two-spin system is discussed using Redfield's semiclassical formulation of the relaxation processes. Time dependences of longitudinal magnetizations are given as a function of the ratio J/δν0. An expression for the nuclear induction signal is given, from which the expected shape of multiplet lines and their behaviors upon saturation under various origins of the relaxation are discussed in detail. The discussion leads to the conclusion that the mechanism of nuclear relaxation can be determined by carefully analyzing the spin multiplet lines on the basis of the theory. Finally, it is shown that there is a possibility of finding the absolute sign of the spin-spin coupling constant in a two-spin system using the multiple resonance method.