A STUDY OF ANIONIC MOTION IN SODIUM THIOCYANATE BY N-14 NUCLEAR-QUADRUPOLE RESONANCE

An anionic motion in sodium thiocyanate was studied by the spin-lattice relaxation time measurements of N-14 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 approximate to 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.