NMR investigation of ionic motion in LiI-KI in the liquid state

Abstract

The longitudinal relaxation time (T1), transverse relaxation time (T2), and chemical shift of 7Li, and the line width and chemical shift of 127I were measured to study ionic motion in the eutectic LiI-KI mixture in the liquid state. T1 and T2 of 7Li are both very long (more than a few seconds). Motioning narrowing is not observed for 7Li, which gives the lower limit of the correlation time, ~10-9 s. The relaxation times of 127I nucleus are too short (less than 100 μs) to measure using the standard pulse methods. Although the resonance peak of 7Li is very narrow and the chemical shift is almost independent of temperature and composition, the resonance peak of 127I is very broad and dependent on temperature and composition, which has been analyzed by assuming two sites of I- and their rapid exchange. The residence time of I- is estimated to be about 10-5 s.