SINGLE-SCAN SIMULTANEOUS MEASUREMENT OF NMR SPIN-LATTICE AND SPIN SPIN RELAXATION-TIMES

An NMR method for measuring both T1 and T2 in a single rapid experiment is described. The technique is applicable to many single-peak and two-peak systems, provided that the spin-lattice and spin-spin relaxation processes are monoexponential in nature. The RF pulse sequence consists of a train of 90° pulses applied with a resonance offset Δf and a pulse repetition time τ chosen so that τΔf = 1 2. The transverse magnetization is sampled once after each pulse. The resulting time-domain signal can be parameterized by the initial average dc offset A0, the final offset Af, and the exponential decay time constant of the offset, Tr. The relaxation times are determined from T1 = A0Tr/Af and T2 = A0Tr/(2A0 - Af). An inversion pulse can be applied just prior to the pulse train to increase the dynamic range of the experiment and to allow measurements when T1 ≅ T2. Relaxation times measured by applying this technique to several one-and two-peak systems are in good agreement with the results obtained from conventional relaxation-time measurement methods. © 1993 by Academic Press, Inc.