Relaxation (NMR) - Relaxation in The Rotating Frame, T_1ρ

Relaxation in The Rotating Frame, T_1ρ

The discussion above describes relaxation of nuclear magnetization in the presence of a constant magnetic field B₀. This is called relaxation in the laboratory frame. Another technique, called relaxation in the rotating frame, is the relaxation of nuclear magnetization in the presence of the field B₀ together with a time-dependent magnetic field B₁. The field B₁ rotates in the plane perpendicular to B₀ at the Larmor frequency of the nuclei in the B₀. The magnitude of B₁ is typically much smaller than the magnitude of B₀. Under these circumstances the relaxation of the magnetization is similar to laboratory frame relaxation in a field B₁. The decay constant for the recovery of the magnetization component along B₁ is called the spin-lattice relaxation time in the rotating frame and is denoted T_1ρ. Relaxation in the rotating frame is useful because it provides information on slow motions of nuclei.