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Title: Theory of long-lived nuclear spin states in methyl groups and quantum-rotor induced polarisation

Long-lived nuclear spin states have a relaxation time much longer than the longitudinal relaxation time T{sub 1}. Long-lived states extend significantly the time scales that may be probed with magnetic resonance, with possible applications to transport and binding studies, and to hyperpolarised imaging. Rapidly rotating methyl groups in solution may support a long-lived state, consisting of a population imbalance between states of different spin exchange symmetries. Here, we expand the formalism for describing the behaviour of long-lived nuclear spin states in methyl groups, with special attention to the hyperpolarisation effects observed in {sup 13}CH{sub 3} groups upon rapidly converting a material with low-barrier methyl rotation from the cryogenic solid state to a room-temperature solution [M. Icker and S. Berger, J. Magn. Reson. 219, 1 (2012)]. We analyse the relaxation properties of methyl long-lived states using semi-classical relaxation theory. Numerical simulations are supplemented with a spherical-tensor analysis, which captures the essential properties of methyl long-lived states.
Authors:
 [1] ;  [2] ; ; ; ; ; ; ; ; ;  [1]
  1. School of Chemistry, University of Southampton, Southampton SO17 1BJ (United Kingdom)
  2. (France)
Publication Date:
OSTI Identifier:
22416053
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COMPUTERIZED SIMULATION; DIFFUSION BARRIERS; MAGNETIC RESONANCE; MATHEMATICAL SOLUTIONS; METHYL RADICALS; POLARIZATION; PROBES; RELAXATION TIME; ROTATION; SOLIDS; SPHERICAL CONFIGURATION; SPIN; SPIN EXCHANGE; TEMPERATURE RANGE 0273-0400 K; TENSORS