Relaxation in the presence of an rf field

The equations that govern the relaxation of a system of nuclear spins in the presence of a radiofrequency (rf) field are studied with the aim of demonstrating the new features that the rf field introduces into the Redfield treatment of relaxation. It is shown under what conditions Redfield relaxation matrix elements reduce to the usual expressions in the absence of an rf field. The potential alteration of experimental relaxation rates by an rf field is considered. ©1997 John Wiley & Sons, Inc. Concepts Magn Reson 9: 347–353, 1997