Larmour frequency

Nuclei Natural abundance % Larmour frequency MHz (at 10 Gauss) Magnetic moment (in nuclear magnetons) Spin (in h units) Electric quadrupole moment (10 cm )... 

Spin—lattice relaxation is the time constant for the recovery of magnetiTation along the z-axis in a NMR experiment. Various methods are available for the measurement of spin lattice relaxation times. The interested reader is referred to the series of monographs echted by Levy on Carbon-13 NMR spectroscopy [44, 45] for more details. The energy transfer between nuclear moments and the lattice , the three-dimensional system containing the nuclei, provides the mechanism to study molecular motion, e.g. rotations and translations, with correlation times of the order of the nuclear Larmour frequencies, tens to hundreds of MHz. We will limit our chscussion here to the simple inversion-recovery Tj relaxation time measurement experiment, which, in addition to providing a convenient means for the quick estimation of Tj to establish the necessary interpulse delay in two-dimensional NMR experiments, also provides a useful entry point into the discussion of multi-dimensional NMR experiments. 

There are many experiments which determine only specific frequency components of the power spectra. For example, a measurement of the diffusion coefficient yields the zero frequency component of the power spectrum of the velocity autocorrelation function. Likewise, all other static coefficients are related to autocorrelation functions through the zero frequency component of the corresponding power spectra. On the other hand, measurements or relaxation times of molecular internal degrees of freedom provide information about finite frequency components of power spectra. For example, vibrational and nuclear spin relaxation times yield finite frequency components of power spectra which in the former case is the vibrational resonance frequency,28,29 and in the latter case is the Larmour precessional frequency.8 Experiments which probe a range of frequencies contribute much more to our understanding of the dynamics and structure of the liquid state than those which probe single frequency components. 

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