A study of anionic motion in sodium thiocyanate by 14N nuclear quadrupole resonance

An anionic motion in sodium thiocyanate was studied by the spin-lattice relaxation time measurements of 14 N nuclear quadrupole resonance. The relaxation time decreased rapidly obeying an Arrhenius equation above T = 375 K. This result suggests the onset of a head-tail reorientational motion of thiocyanate ion with an activation energy of ≈ 95 kJ mol −1 . The origin of an anomalous temperature dependence of the quadrupole coupling constant is reinvestigated in relation to the anionic motion. It is concluded that a gradual change in electronic state of the anions, not the anionic motion, in the crystal with varying temperature is responsible for the anomaly claimed previously. Intermolecular interaction between N and Na atoms is suggested to be the most important factor in the origin of the change in the electronic state of the anion.