SELECTIVE PULSES AND THEIR APPLICATIONS T O THE ATTRIBUTION OF RESONANCES AND TO STRUCTURE DETERMINATION IN NMR

Aspects of shaped selective pulses and their applications in assignmen t and structure determination by NMR are considered. Specifically, str ategies for the design of selective pulses for in-phase excitation are covered. In the simplest case, 270-degrees Gaussian pulses are used t o excite a multiplet with only a small residual phase dispersion. In m ore demanding cases, more complex analytical pulse shapes are discusse d. The most succesful pulse shapes to date are described by either a s um of Gaussians, or a Fourier series. Both types of pulse can produce excitation over a very well defined region with virtually no phase dis persion. We also consider multi-dimensional techniques which use shape d pulses to assign resonances, and to derive coupling constants. The s oft-COSY experiment is considered in some detail, followed by a brief description of experiments which are designed to simplify complex spec tra on die basis of the topologies of networks of coupled spins. The m ethods are illustrated with examples from peptides and DNA fragments.