Multiple-Pulse NMR Experiments

Abstract

This chapter explains the multiple-pulse NMR with experiments and to interpret the NMR spectra, obtained by the application of multiple-pulse experiments, there is no need to know the detailed mechanism of the different multiple-pulse experiments in detail. To understand the mechanism better on why signal resonances appear to be negative and some as positive signals, the chapter discusses some simple multi-pulse experiments for the reader to understand better. While investigating the relaxation mechanisms of the carbon nuclei, discussions of two kinds of relaxation mechanisms namely spin–lattice relaxation, T 1 and spin–spin relaxation, T 2 are explained. The experiment performed to cancel all the effects that result from the inhomogeneity of the magnetic field namely he spin–echo experiment is explained. An explanation is provided for the J -modulated spin–echo experiment. The section on signal enhancement by population transfer namely the selective population transfer and selective population inversion methods are described. The INEPT (Insensitive Nuclei Enhanced by Polarization Transfer) experiment and the refocused INEPT experiments are explained. The detail of DEPT (Distortion less Enhancement by Polarization Transfer) experiment which is a useful method to determine the multiplicity of carbon atoms is available.