Decoupling Methods
Summary
Decoupling is one of the most used NMR techniques. The aim of the method is to remove unwanted spin-spin interactions and it can be used either for structure elucidation purpose or for improving resolution and sensitivity due to simplified multiplet structure.
Depending on the implementation decoupling methods can be divided into homonuclear and heteronuclear ones. In the former case both continuous wave irradiation(double resonance) and bandselective homodecoupling may be used, more detailed description of the homonuclear methods is available elsewhere.
Heteronuclear decoupling also makes use of continuous wave irradiation (selective and off-resonance decoupling), however, it has been shown that for broadband applications pulsed technique gives superior results. Recently many decoupling sequences were developed covering almost all practical needs. A typical decoupling pulse sequence consists on wideband composite or shaped inversion pulse united into a cycle or supercyle to compensate residual imperfections.
A short description of the most popular modern decoupling methods for liquid state NMR is available on the Internet.
The problems discussed in the literature:
Books and Reviews
Shaka A.J., in "Encyclopedia of NMR", 1996, v.3, pp. 1558-1564 (19 References). Decoupling Methods.
Levitt M.H., Freeman R., Frenkiel T., in "Advances in Magnetic Resonance", ed. Waugh J.S., Academic Press, N.Y. and London, 1983, v. 11, p. 47-110.
Shaka A.J., Keeler J., Progress NMR Spectroscopy, 1987, v. 19, p. 47-129.
Derome E., Pergamon Press, Oxford, 1987-280. Modern NMR Techniques for Chemistry Research.
Ernst R.R., Bodenhausen G., Wokaun A., Clarendon Press, Oxford, 1987-610. Principles of NMR in One and Two Dimensions.