Low temperature dynamics of hydrazinium ions in lithium hydrazinium sulphate (LHS) studied by electron spin echo (ESE) technique

The temperature dependence of the phase memory time TM in γ-irradiated lithium hydrazinium sulphate, LiN2H5SO4, single crystal has been measured in the temperature range 4.2–290 K. Two minima in TM(T) at 115 and 175 K were observed. The low-temperature TM minimum has been identified as due to librational motions of the N2H5+ hydrazinium ion with an activation energy of 0.045 eV. The TM minimum at 175 K has been assigned to rotation of the –NH3+ end of the hydrazinium ion with an activation energy of 0.074 eV. The activation energies have been compared with the results of a previous NMR and Raman spectroscopic studies of this crystal.