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Details van artikel 9 van 17 gevonden artikelen
| Titel: |
N.M.R. line shape and spin-locking in slowly tumbling methyl groups |
| Auteur: |
Khazanovich, T. N. Mironov, V. D. |
| Verschenen in: |
Molecular physics |
| Paginering: | Jaargang 55 (1985) nr. 1 pagina's 145-159 |
| Jaar: |
1985-05 |
| Inhoud: |
N.M.R. line shape, rotating frame spin-lattice relaxation, and the decay of echo amplitudes in the pulse sequence (90oy-τ-(90ox-2τ)n-90ox-τ) have been considered for protons of a methyl group the symmetry axis of which is tumbling by slow rotational diffusion as the group rapidly reorientates around the axis. Only dipole-dipole interactions have been taken into account. The method of stochastic Liouville equations (SLE) has been applied, whilst the part of the internal dipole interaction which is not invariant under spin interchange and intergroup dipole interactions were treated by perturbation theory. The results of the SLE method have been compared with those of Bloch-Redfield equations in which all the interactions are treated by perturbation theory. The line shape calculated from perturbation theory was found to be close to the exact one in the range of slow motion of the symmetry axis and relatively slow internal rotations. But this shape strongly differs from the exact one in the case of rapid internal rotation. The analysis of relaxations in continuous and pulsed spin-locking experiments has confirmed the previous conclusion that simple equations of perturbation theory are applicable to describe such experiments provided correlation times are comparable with (or less than) the period of precession in the local field and one can measure spectral densities of molecular motion at frequencies only slightly greater than the local field frequency. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 9 van 17 gevonden artikelen
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