Susceptibility, lineshape, and shimming in high-resolution NMR

Abstract

The field inhomogeneity caused by an object of known susceptibility and shape is calculated. The field perturbation is derived using the method of equivalent magnetic charges. Lineshapes are calculated by summing Lorentzians over the sample volume and are verified experimentally by observing changes caused by introducing material into the vicinity of a previously shimmed NMR sample. Such lineshapes can be used for the determination of susceptibility of materials.