A modified fast inversion-recovery technique for spin-lattice relaxation measurements☆

Abstract A modified version of the fast inversion-recovery (FIR) method for measuring spin-lattice relaxation times is proposed. Whereas the FIR method employs a fixed time W between successive 180°, τ, 90°, sequences, the modified FIR method uses a fixed value of δ = W + τ , so that W decreases as τ increases. Both FIR and modified FIR methods are shown to be capable of nearly equal precision under conditions of ideal 180 and 90° pulses. With imperfect pulses, however, the modified FIR method circumvents certain systematic errors inherent in the FIR method. Conditions under which such errors might become significant are discussed.