Appendix B: Introduction to FFC NMR Theory and Models for Complex and Confined Fluids

This appendix intends to provide the reader with the basic principles of the fast field cycling (FFC) technique for studying fluids in complex systems, such as, for example, porous media or cementitious materials. The topics covered do not claim completeness and total formal correctness. Over time, a wide variety of mathematical models have been developed to interpret the results of FFC measurements performed on samples of different types. Only a simplified review of a short and arbitrary list of FFC models, effective in practical applications, is provided in the appendix. No application examples or comparisons among models are shown. The reader is warmly invited to continue the study of the vast specialized literature, starting from the bibliography proposed at the end of the appendix (References) and the references quoted therein. A minimal knowledge of the concepts and terminology used in both quantum mechanics and NMR is required to efficiently and profitably use the material presented in this appendix.