Larmor Frequency in Heterogeneous Media

The Larmor frequency shift is found in porous media consisting of NMR-reporting fluid filling a connected pore within an NMR-invisible matrix for the case of fast diffusion in the fluid. The matrix material has a distinct location-independent anisotropic magnetic susceptibility tensor that induces a heterogeneous microscopic magnetic field when exposed to the strong main field of an NMR device. Aside from the connectivity of the pore, the matrix geometry is arbitrary.