1. Characteristics of non-medical NMRI

1.1 General

In chemical and spectroscopic analysis, the analyst is usually required to characterize a sample as a whole, which may itself be extracted from a larger, heterogeneous sample. It is often assumed that the information gathered in a fraction of the sample characterizes the whole sample without distinction. This approach applies to most chemical analyses. The unaltered characterization of heterogeneous samples, or samples undergoing rapid changes in physical or chemical state, is more problematic.

Apart from the technique of cutting the sample, followed by analysis of each individual piece, few analytical methods are available to study the internal chemical or morphological heterogeneities of massive samples. Tomography from computer-processed X-ray...