Theory of diffusion in a porous medium with applications to pulsed-field-gradient NMR

A Fourier approach is applied for calculating the pulsed-field-gradient-spin-echo amplitude M(k,t) of a fluid in a porous medium with a periodic microgeometry. The method is most effective for long times t, but works quite well down to times that are short enough so that asymptotic short-time approximations of the diffusion process are still valid. The method can be applied regardless of the value of the porosity or the shape of the periodic pore space. Preliminary results are presented for simple cubic arrays of spherical obstacles in a fluid.