J. Etrillard et al., Cl-35 NQR and H-2 NMR analysis of the critical dynamics close to the displacive normal-incommensurate phase transition in an organic crystal, APPL MAGN R, 17(2-3), 1999, pp. 301-313
Nuclear magnetic resonance MMR) experiments, Cl-35 nuclear quadrupole reson
ance (NQR) and H-2 NMR, have been performed close to the displacive normal-
incommensurate phase transition in the organic crystal of bis-(4-chlorophen
yl)-sulfone. Calculations using coherent neutron scattering results show th
at the soft-mode contribution cannot explain the rapid increase of the spin
-lattice relaxation rates close to the transition temperature. Calculations
of the spectral densities taking into account the existence of a central-p
eak phenomenon describe both Cl-35 NQR and H-2 NMR spin-lattice relaxation
rates on approaching the phase transition. In this way, the width of the ce
ntral peak can be estimated to be in the range of several gigahertz.