NMR relaxation study of disorder in the mixed system BP x GPI(1-x) and the low temperature transition from classical to quantum rotation

Ramanuja, MN and Ramesh, KP and Ramakrishna, J (2009) NMR relaxation study of disorder in the mixed system BP x GPI(1-x) and the low temperature transition from classical to quantum rotation. In: Molecular physics, 107 (7). pp. 643-652.

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Abstract

1H NMR spin-lattice relaxation time (T1) studies have been carried out in the temperature range 100 K to 4 K, at two Larmor frequencies 11.4 and 23.3 MHz, in the mixed system of betaine phosphate and glycine phosphite (BPxGPI(1-x)), to study the effects of disorder on the proton group dynamics. Analysis of T1 data indicates the presence of a number of inequivalent methyl groups and a gradual transition from classical reorientations to quantum tunneling rotations. At lower temperatures, microstructural disorder in the local environments of the methyl groups, result in a distribution in the activation energy (Ea) and the torsional energy gap (E01). For certain values of x, the magnetisation recovery shows biexponential behaviour at lower temperatures.

Item Type:	Journal Article
Publication:	Molecular physics
Publisher:	Taylor & Francis
Additional Information:	Copyright of this article belongs to Taylor & Francis.
Keywords:	NMR Relaxation; Disorder; Mixed System; Betaine Phosphate (BP); Glycine Phosphite (GPI); Quantum Tunneling; Biexponential Relaxation; Distribution Of Activation Energy
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	03 Jan 2010 11:07
Last Modified:	19 Sep 2010 05:34
URI:	http://eprints.iisc.ac.in/id/eprint/20727

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