The half-wave triplet pulse sequence for determination of longitudinal relaxation rates of single line spectra

A modified pulse triplet sequence has been developed for the measurement of longitudinal relaxation rates, 1/T₁. The analysis of this "half-wave" triplet method takes account of transverse relaxation occurring during the triplet, so that the approximation employed in previous use of the triplet sequence, viz., that the interval τ between component pulses of the triplet be much less than the interval δt-2τ between successive triplets, is no longer required. Values of 1/T₁ derived from triplet measurements and a Carr-Purcell spin echo measurement of 1/T₂ on test samples of aqueous polymethacrylate and copper sulfate are in good agreement with values of 1/T₁ obtained from conventional Carr-Purcell 180°-t-90° measurements. The half-wave triplet sequence would be useful for those cases where a single line is present in the spectrum: two repetitions of the triplet sequence to obtain n points on a magnetization recovery curve and a determination of T₂ are required for the determination of 1/T₁n this method, compared to at least n repetitions (for n points) in the Carr-Purcell 180°-t-90° method.