Restricted diffusion in NMR in arbitrary inhomogeneous magnetic fields and an application to circular layers.

The multiple correlation function technique is a versatile approach for the computation of the nuclear magnetic resonance (NMR) magnetization of spins diffusing in inhomogeneous fields. The difficulties in deriving the required interaction matrices are one of the main limitations of this technique. In this work, methods to compute the interaction matrices of general magnetic field profiles from those of linear fields by basic matrix manipulations are presented. As an example, susceptibility induced magnetic field profiles that are generated by cylindrical capillaries residing in homogeneous magnetic fields are considered.