Spin dynamics in many-body dipolar system
- Univ. of California, Berkeley, CA (United States)
Our studies of the many-body character of the spin dipolar interaction in solid-state NMR reveal some unusual and interesting physical chemistry. (I) Rigid Lattice. The transverse correlation functions are calculated by the Kubo-Tomita theory and compared with the measurements. The results suggest that the damped oscillating long-time tail of the dipolar dephasing may be ascribed to the long-range cross correlation governed by the Ising interaction. This gives satisfactory explanation to the recent surprising observation of substantial line-narrowing with long acquisition delays. (ii) Slow Motion. The possibility of effective dipolar decoupling induced by slow lattice motion is demonstrated based on a generalized relaxation formulation and real experiments. (iii) Motional Narrowing. Comparison of some diffusion jump rates determined from NMR motional-narrowing studies and other more direct techniques yields order of magnitude differences in the prefactor of the Arrhenius equation and uncertainties of the activation energies. Numerical experiments illustrate that these {open_quotes}prefactor anomalie{close_quotes} may arise from the highly nonexponential time correlation of the fluctuating local fields due to correlated vacancy migration and reduced dimensionality.
- OSTI ID:
- 560377
- Report Number(s):
- CONF-970443-; TRN: 97:005895-0282
- Resource Relation:
- Conference: 213. national meeting of the American Chemical Society, San Francisco, CA (United States), 13-17 Apr 1997; Other Information: PBD: 1997; Related Information: Is Part Of 213th ACS national meeting; PB: 2904 p.
- Country of Publication:
- United States
- Language:
- English
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