The internal structure of systems of particles in a liquid is stud-5 mm in the case of the light scattering method. They are ied with a novel NMR technique based on the measurement of the inefficient for systems with a larger characteristic size such squared modulus of the magnetization in presence of a pulsed field as non-Brownian suspensions, porous media, and fluidized gradient. The formalism is analogous to the one used in classical beds. In this paper, we show that information about the scattering techniques (light, X-rays, neutrons); it allows similar structure of systems with a characteristic size larger than 10 information to be obtained about the structure (in particular, the mm can be gained with NMR, the pair correlation function structure factor S(q)). The main improvement is that the range being derived with a formalism analogous to the classical of particles sizes is 10 mm to 1 mm, as compared with the range scattering techniques.
of the scattering techniques (õ5 mm). The NMR technique was
The pulsed field gradient spin-echo (PFGSE) NMR techvalidated by studying packings of spherical particles of mean diameter 240 mm created by sedimentation. The profile of the experi-nique has been used for many years to study diffusion and mental squared modulus of the magnetization versus the wave flow in porous media. This method provides information vector provides results for the mean size of particles and the comabout the microstructure in the host material when boundpacity. The main feature is that it depends on the pair distribution aries hinder normal diffusive transport (4). Recent works function, and the present results are in good agreement with a point out that the distribution of probability of the molecular model based on the Percus-Yevick approximation. This technique displacements P(Dz, t), along the z axis, during an interval is then particularly adapted to systems such as non-Brownian of time t, can be obtained using the PFGSE sequence; the suspensions, fluidized beds, porous media, and sediments. ᭧ 1998 echo signal M 1 being a function of the intensity of the field Academic Press gradient G, the probability P(Dz, t) then appears as the Fourier transform of M 1 (G). This technique has been introduced by K. Fukuda and A. Hirai (5) in order to find the axial