Investigation of NMR Relaxation Data Using Dipole Correlation Function

In this work, the theories of the relaxation mechanism leading to the dipole-correlation function, playing an important role in the analysis of the spin-lattice and spin-spin relaxation times in magnetic rezonance, are investigated. An evaluation of these theories is made in the light of the experimental data. It is found that the spin-lattice relaxation data of the glassy medium, particularly, do not obey much the single dipole correlation function of the form exp(-t/τ), obtained from the classical Debye relaxation theory of the polar molecules. On the other hand, it is observed that the data can be represented by the non-exponential correlation function driven from the cooperative relaxation models based on the spin-defect interactions. Furthermore, it is shown that the spin-spin relaxation time, obtained from the dipole-correlation function representing the relaxation of the one-dimensional Ising spins with nearest neighbor interactions, is in complete agreement with the experimental observations.