Multiple resonance

[Introduction in lieu of Abstract] The trend noted in the previous article in this series towards greater routine use of all aspects of multiple resonance has continued during the two-year period up to June 1976 currently under review. The most rapid developments have been associated with pulsed Fourier transform experiments, and while some of this work has been essentially a repeat of older CW experiments, the different time-scale available has led to the observation of interesting new effects. We confine ourselves to systems in which all resonating spins are nuclear and further limit discussion of work involving bandshape analysis and the solid state to a brief mention since these topics are treated more fully in other chapters. Routine applications of multiple resonance (especially spectral simplification, off-resonance assignments of <sup>13</sup>C spectra, and straightforward spin-tickling experiments for the determination of the relative signs of coupling constants) are also either dealt with summarily or are ignored.<br> Several reviews have appeared during our period which contain some mention of multiple resonance, and attention has been drawn to the economic advantages of using double resonance rather than direct FT to get the n.m.r. parameters of many of the less common nuclei.</br&gt