35Cl NQR and calorimetric reinvestigation of the incommensurate phase of bis(4-chlorophenyl) sulfone : evidence for no lock-in transition

35Cl NQR and2H NMR analysis of the critical dynamics close to the displacive normal-incommensurate phase transition in an organic crystal

“…Precise acquisition of the 35 C1 NQR lineshape has been performed in the temperature range from 280 to 145 K. Far from the transition, the lines are almost Gaussian, and due to the high quality obtained with this single crystal, the NQR linewidth found is about 1.4 kHz at room temperature, much narrower than the ones previously reported in the literature [13][14][15]. This allows us to precisely follow its temperature evolution in the normal phase and reveals a significant increase on approaching the phase transition.…”

“…The low damping of the critical excitations in BCPS allows the direct observation of the saturation of the frequency of the soft mode close to the transition. Resonance techniques, including 35 C1 NQR [13][14][15] and proton NMR [16] have shown that the spin-lattice relaxation time T, is dominated near Ti by collective critical fluctuations. With new 35C1 NQR and 2H NMR studies, we have obtained reliable experimental data above and through the transition that support the validity of the CP theory.…”

NMR line shape analysis in the incommensurate phase of bis(4‐chlorophenyl)sulfone

“…Bis(4-chlorophenyl)sulfone or 4.4′-Dichlorobiphenyl Sulfone, (ClC 6 H 4 ) 2 SO 2 (henceforth abbreviated as BCPS) crystals experience a phase transition at a temperature of T i = 150 K from a normal phase (N) into a structurally incommensurately modulated phase [1] which was found to be stable [2,3] down to the lowest temperature investigated (4.2 K). The mechanism of the phase transition was analysed [4][5][6][7] by studying the lattice dynamics within a rigid-body approximation for BCPS molecules.…”

A Molecular Dynamics Study of an Incommensurate Modulation Compound: 4, 4′-Dichlorobiphenyl Sulphone

“…This observation has created a new interest in this compound , which has since then been extensively studied by X-ray diffraction [2,3], neutron scattering [4], NMR [5], NQR and Raman spectroscopy [6,7]. Elastic neutron measurements, Cl NQR and calorimetric measurements have indicated that the incommensurate phase is stable down to very low temperature (4.5 K) with the presence of high-order satellite reflections and intensities increasing on cooling [8,9]. X-ray and neutron diffractions have shown that the wave vector of the incommensurate modulation, q s = 0.78b * varies smoothly with the temperature in the whole IC phase [2,3].…”