Analysis of nuclear relaxation in granular systems

AUTOR(ES)

Rabbani, Said R., Mendonça, Christovam, Mamani, J. B, Cervantes R., Hernán

FONTE

Brazilian Journal of Physics

DATA DE PUBLICAÇÃO

2006-03

RESUMO

The longitudinal nuclear magnetic relaxation time, T1, of powdered samples was analyzed following the theory proposed by Browstein and Tarr to explain the T1 reduction of water confined in biological cells and the proposed by Rabbani and Edmonds where the molecular diffusion in liquids is substituted by spin diffusion to interpret the T1 behavior in solid particles. We have shown that the multiexponential character of magnetization decay in solid particles with a narrow band size distribution allows to evaluate the spin diffusion coefficient of this material. On the other hand if the diffusion coefficient of a material is given and the average size of a sample of this material is known the relaxation decay curve can be used to determine the surface relaxivity as well as the relative size of particles present in the other samples of same material. However, this analysis is unable to provide the absolut measurement of the grain sizes. Furthermore, it is shown that the grain geometry does not influence the relaxation decay curve.

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