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1 H NMR spin–lattice relaxation studies in Betaine phosphate (BP) – Transition from classical to quantum rotation
Author(s) -
Ramanuja M. N.,
Ramesh K. P.,
Ramakrishna J.
Publication year - 2006
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200541262
Subject(s) - chemistry , condensed matter physics , relaxation (psychology) , spin–lattice relaxation , spin diffusion , betaine , antiferroelectricity , atmospheric temperature range , activation energy , larmor precession , lattice (music) , ferroelectricity , proton spin crisis , proton , diffusion , physics , nuclear magnetic resonance , thermodynamics , quantum mechanics , magnetic field , psychology , social psychology , biochemistry , dielectric , acoustics
We report here the results of our 1 H NMR spin–lattice relaxation time ( T 1 ) studies in betaine phosphate which is ferroelectric below 86 K and antiferroelectric below 81 K. The experiments have been carried out in the temperature range 300 to 4 K, at two Larmor frequencies 11.4 and 23.3 MHz. The T 1 data (300–100 K) has been analysed using modified BPP equation based on Ikeda's model. CH 3 protons are found to relax other protons via spin diffusion. The low temperature ( T < 100 K) T 1 data has been analysed following Lourens model which considers the gradual transition from classical motions to quantum regime. At low temperatures, when classical processes tend to freeze, reorienting groups apparently have minute differences and hence create a distribution in the energy values ( E a and E 01 ) and pre‐exponential factors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)