PULSED-GRADIENT SPIN-ECHO NMR FOR PLANAR, CYLINDRICAL, AND SPHERICAL PORES UNDER CONDITIONS OF WALL RELAXATION

The theory of pulsed-gradient spin-echo NMR in the case of molecules trapped within pores has been extended to include wall-relaxation effects. Expressions are obtained for the echo attenuation under the narrow-gradient-pulse condition for rectangular, cylindrical, and spherical pores. The cylindrical result is new, while those for rectangular and spherical pores differ from previously published formulas. The present results are verified in a number of special limits. It is shown that ''diffraction'' effects are still strongly apparent when wall relaxation is taken into account. Furthermore, deviations in the pore radius, a, obtained from the position of the echo minimum, are weak in practice, provided that the time between the gradient pulses exceeds a(2)/D, where D is the molecular self-diffusion coefficient. (C) 1995 Academic Press, Inc.