Scholz, I. and Hodgkinson, P. and Meier, B.H. and Ernst, M. (2009) 'Understanding two-pulse phase-modulated decoupling in solid-state NMR.', Journal of chemical physics., 130 (11). p. 114510.
A theoretical description of the two-pulse phase-modulated (TPPM) decoupling sequence in magic-angle spinning NMR is presented using a triple-mode Floquet approach. The description is formulated in the radio-frequency interaction-frame representation and is valid over the entire range of possible parameters leading to the well-known results of continuous-wave (cw) decoupling and XiX decoupling in the limit of a phase change of 0° and 180°, respectively. The treatment results in analytical expressions for the heteronuclear residual coupling terms and the homonuclear spin-diffusion terms. It also allows the characterization of all resonance conditions that can contribute in a constructive or a destructive way to the residual linewidth. Some of the important resonance conditions are described for the first time since they are not accessible in previous treatments. The combination of the contributions from the residual couplings and the resonance conditions to the effective Hamiltonian, as obtained in a Floquet description, is shown to be required to describe the decoupling behavior over the full range of parameters. It is shown that for typical spin system and experimental parameters a 13C linewidth of approximately 12 Hz can be obtained for TPPM decoupling in an organic solid or a protein. This is a major contribution to the experimentally observed linewidths of around 20 Hz and indicates that decoupling techniques are still one of the limiting factors in the achievable linewidths.
|Keywords:||Biological NMR, Magic angle spinning, Molecular biophysics, Organic compounds, Proteins, Spin dynamics, Spin echo (NMR), Spin systems.|
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|Publisher Web site:||http://dx.doi.org/10.1063/1.3086936|
|Publisher statement:||Copyright 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Scholz, I. and Hodgkinson, P. and Meier, B.H. and Ernst, M. (2009) 'Understanding two-pulse phase-modulated decoupling in solid-state NMR.', Journal of chemical physics., 130 (11). p. 114510 and may be found at http://dx.doi.org/10.1063/1.3086936|
|Record Created:||24 Oct 2012 16:05|
|Last Modified:||24 Oct 2012 16:26|
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