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'Relaxation' in keywords Facet   Publication Year 1991  [X]
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1991[X]
1Author    MarcoL H Gruwel1, RoderickE. WasylishenRequires cookie*
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 Abstract    e u te riu m N M R S tu d y o f th e S o lid -S o lid P h a s e T ra n s itio n in P h e n e th y la m m o n iu m B ro m id e 30, 1991 Using 2H NMR, the dynamics of the cation in phenethylammonium bromide were studied in the two solid phases. Line shape and spin-lattice relaxation rate studies of the ammonium headgroups and the adajacent methylene groups indicate the onset of alkyl-chain motion prior to the first order phase transition. In the low-temperature phase the line shape and the spin-lattice relaxation rates of the -ND3 groups are consistent with C3 jumps and an activation energy of 54±4 kJ mol"1. However, in the high-temperature phase the spin-lattice relaxation studies indicate the presence of small-angle diffusion of the -ND3 groups around the C3 symmetry axis. In this phase the -CD2-groups show line shapes typical of large-amplitude two-site jumps occurring at a rate > 107 s~ l. In the low-temperature phase, at temperatures below 295 K, the -CD2-2H NMR line shapes indicate that the C-D bonds are essentially static. 
  Reference    Z. Naturforsch. 46a, 691 (1991); received March 
  Published    1991 
  Keywords    2H NMR, Phase transition, Relaxation, Molecular jumps 
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 TEI-XML for    default:Reihe_A/46/ZNA-1991-46a-0691.pdf 
 Identifier    ZNA-1991-46a-0691 
 Volume    46