DIPOLAR SPIN FLUCTUATIONS IN THE ROTATING FRAME - RELAXATION MECHANISM

Under rf irradiation a system of spins linked by dipolar couplings can order along the external rf field or along the internal local fields. The decay of rotating frame magnetization proceeds either directly by thermalization with the lattice (molecular motion) or by a spin-spin coupling to the dipolar reservoir, independent of molecular motions. The dynamics of this cross coupling and implications for the usual relaxation measurement are examined. For adamantane at room temperature a Lorentzian correlation function describes the proton dipolar fluctuation spectrum under irradiation. © 1979.