Raman and i.r. studies of phase transitions in (CH<inf>3</inf>)<inf>3</inf>NHClO<inf>4</inf>

(CH3)3NHClO4 belongs to the monoclinic system with space group P21/m (C22h) at 300 K. Raman and i.r. spectra (20-5000cm-1) of single crystals and polycrystalline samples of (CH3)3NHClO4 and its N-deuterated derivative were investigated in the temperature range 90-500 K. A systematic temperature-dependence study of the frequencies and band-widths show the existence of phase transitions at 397 and 480 K. The main features of the spectra, particularly in the ambient temperature phase, are assigned with the aid of factor group analysis. The spectral changes indicate that both cations and anions undergo quasiisotropic motion in phases II and I and self-diffusion in phase I. © 1988.