Second moment of multiple-quantum NMR and a time-dependent growth of the number of multispin correlations in solids

Journal Article · Fri Dec 15 04:00:00 EST 2006 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776106120089· OSTI ID:21067586

The time evolution of multispin correlations (the growth of the number of correlated spins as a function of time) can be observed directly using the multiple-quantum nuclear magnetic resonance spectroscopy of solids. A quantity related to this number, namely, the second moment <n{sup 2}(t)> of the intensity distribution of coherences of different orders in the multiple-quantum spectrum can be calculated using the theory proposed in this work. An approach to the calculation of the four-spin time correlation function through which this moment is expressed is developed. The main sequences of contributions in the expansion of this function into a time power series are summed using the approximation of a large number of neighbors both for systems with a secular dipole-dipole interaction and for systems with a nonsecular effective interaction. An exponential dependence of <n{sup 2}(t)> is obtained. The value of <n{sup 2}(t)> is additionally calculated using an expansion in terms of orthogonal operators for three model examples corresponding to different limiting realizations of spin systems. It is shown that the results of the microscopic theory at least qualitatively agree with both the results obtained for model examples and experimental results obtained recently for adamantane.

• OSTI ID: 21067586
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 6 Vol. 103; ISSN JTPHES; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
CORRELATION FUNCTIONS
CORRELATIONS
CRYSTAL GROWTH
CYCLOALKANES
DIPOLES
DISTRIBUTION
EVOLUTION
NUCLEAR MAGNETIC RESONANCE
POWER SERIES
SPECTRA
SPECTROSCOPY
SPIN
TIME DEPENDENCE