ABSTRACT
This chapter examines dynamic processes since the Nuclear magnetic resonance (NMR) studies of chemical systems. It deals with nuclear spin relaxation only as a parameter affecting the NMR experiment. Spin relaxation rates depend on time-dependent fluctuations in the local magnetic environment, and careful measurement and analysis of those rates can provide valuable information about molecular dynamics. A thorough analysis of relaxation behaviour as a function of parameters such as magnetic field strength, temperature and nuclear spin type can provide details of motion and chemical dynamics in small and large molecules. Dynamic processes in macromolecules that are of interest for chemical or biological processes are much slower than the librations and torsions that are represented by the fast local effective correlation times, or even the overall correlation time. The most important dynamic processes for nuclear spin relaxation are overall molecular tumbling, segmental motions of molecules, and chemical exchange.
