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单词 magic-angle spinning
释义
magic-angle spinning

Chemistry
  • A technique used in solid-state nuclear magnetic resonance (NMR) for making the line widths smaller. In magic-angle spinning, both the dipole-dipole interaction and the chemical shift anisotropy have the angular dependence 1–3cos2θ‎, where θ‎ is the angle between the principal axis of the molecule and the applied magnetic field. The ‘magic angle’ is the angle θ‎ that satisfies 1–3cos2θ‎ = 0 and is given by θ‎ = 54.74°. In magic-angle spinning the material is spun very rapidly at the magic angle to the applied magnetic field so that the dipole-dipole interactions and chemical shift anisotropies average to zero. It is necessary for the frequency of spinning to be at least as large as the width of the spectrum. This technique has been extensively used, with the spinning between 4 and 5 kHz.


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