Investigation of NMR Relaxation Data Using Dipole Correlation Function

Ş Yılmaz,S Bozdemir

doi:10.3390/mca2030131

Abstract

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.

Highlights

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
If an external magnetic field is applied to a bipolar spin system magnetic moments tend to orient themselves to the direction of the field Due to local field and dipole-environment interaction, these magnetic moments may not completely align themselves with the external field
When the external field becomes zero these two componellts of different orientation take two different relaxation times The relaxation time in the direction of the local field is called spin-lattice relaxation time T,. while the relaxation time of perpendicular to the field is called spin-spin relaxation time T2 (11 )

Summary

Introduction

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. When the external field becomes zero these two componellts of different orientation take two different relaxation times The relaxation time in the direction of the local field is called spin-lattice relaxation time T,. When a magnetic field of direction z is applied to a bipolar spin group magnetization Mo acquired by the material medium for spin-lattice relaxation can be written as dlv/!. The concept of correlation function based upon the idea that when a spin system is excited.

Results

Conclusion