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Appendix C29Si CP Mas NMR Cross polarization magic angle spinning nuclear magnetic resonance

Publisher
Elsevier Science & Technology
Identifiers
DOI: 10.1016/s0167-2991(06)81525-9
Disciplines
  • Chemistry

Abstract

Publisher Summary The magic angle spinning technique is based on the appropriate averaging of the various solid-state interactions, by spinning the sample at a certain angle to the applied magnetic field. The chemical shift anisotropy (CSA) is the width of the spread (chemical shift of the nucleus when it is parallel to the applied magnetic field minus the chemical shift when it is at right angles to it). This anisotropic part of the chemical shift is proportional to 3cos2(θ) - 1. The angle θ is the angle that, in this instance, the A-X-B axis of the molecule makes with the applied magnetic field. When this angle is 54,7˚ the anisotropic contribution to the chemical shift becomes zero and the spectrum that is obtained approximates that of a solution spectrum in terms of resolution. This is the basic concept of magic angle spinning NMR: the sample is placed in a rotor, spinning at high speed around an axis at 54,7˚ to the axis of the applied magnetic field.

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