Dynamics of the Pinned Modulation Wave in Incommensurate bis (4-chlorophenyl) sulfone (BCPS)

We show that both the anomalously huge resonance-frequency dependence of the ${}^{35}\mathrm{Cl}$ nuclear quadrupole resonance (NQR) spin-lattice relaxation time in BCPS, reported here for the first time, and its anomalous temperature dependence can be explained by large-scale fluctuations of the pinned modulation wave instead of small-scale fluctuations (phasons and amplitudons). The results were obtained by measuring the laboratory ( $T_{1Q}$) and rotating frame ( $T_{1Q,\rho }$) ${}^{35}\mathrm{Cl}$ relaxation times. This is the first time that an effective resonance frequency dependence of the spin-lattice relaxation rate was measured in pure NQR.