The T1 and T2 Relaxation Times Distribution for the 35Cl and 14N NQR in Micro-composites and in Porous Materials

The paper describes the results of an experimental study of the 35Cl and 14N nuclear quadrupole resonance in composite and porous materials, the influence of the environment and the crystallite size of powder on the nuclear quadrupole resonance line widths, as well as on the spin–spin and spin–lattice relaxation times. It is established that the spin–lattice relaxation time has a unimodal distribution, and the spin–spin relaxation time—bimodal distributions for all the investigated samples. The idealized distribution function of the relaxation times is obtained on the assumption that the concentration of inhomogeneities and relaxativity decreases with an increasing distance from the surface into the interior of the crystallite exponentially. It is shown that the model with the spin diffusion explains the shortening of the decay signal with decreasing grain size, but this is not confirmed by the experimental distribution of relaxation times obtained by means of the inverse Laplace transformation.