Relaxation of Multiple Quantum NMR Coherences in Quasi-One-Dimensional Spin Systems

Abstract

Dynamics and relaxation of the multiple quantum (MQ) NMR coherences of the zeroth and second orders are studied experimentally and theoretically in a quasi-one-dimensional chain of nuclear spins

Experimental and theoretical investigations of quantum state transfer and decoherence processes in quasi-one-dimensional systems in multiple-quantum NMR experiments

“…Our calculations demonstrate [29] that the MQ NMR coherence of the zeroth order is not subject to the dipolar relaxation in the ZZ-model. However, the experimental investigation [29] performed using quasi-one-dimensional chains of 19 F nuclei in calcium fluorapatite Ca 5 (PO 4 ) 3 F shows the dipolar relaxation of the MQ NMR coherence of the zeroth order due to the flip-flop part of the Hamiltonian (19). The experimental data [29] also demonstrate that relaxation does not lead to the full disappearance of the MQ NMR of the zeroth order.…”

“…We have shown [29] that the decay of the MQ NMR coherences of the second order conforms reasonably well to a Gaussian function S(t) = exp{− M2(τ )t 2 2 }, where the second moment M 2 (τ ) of the line shape of this coherence is…”

“…However, the experimental investigation [29] performed using quasi-one-dimensional chains of 19 F nuclei in calcium fluorapatite Ca 5 (PO 4 ) 3 F shows the dipolar relaxation of the MQ NMR coherence of the zeroth order due to the flip-flop part of the Hamiltonian (19). The experimental data [29] also demonstrate that relaxation does not lead to the full disappearance of the MQ NMR of the zeroth order. Relaxation ends with the stationary intensity of that MQ coherence.…”

“…Relaxation of MQ NMR coherences in one-dimensional systems has been studied earlier [10,11] using the second moments of the line shapes of the MQ coherences of the zeroth and second orders. We suggested [29] to perform an analogous investigation using the ZZ-model, where only the ZZ-part of the DDI is taken into account.…”

“…An investigation of the relaxation process with the Hamiltonian (19) is too complicated. However, the problem is substantially simplified [29], if we restrict ourselves to the ZZ-part of H dz only and consider the Hamiltonian…”