Order–disorder transition in triethylenediamine: A Raman scattering study

Order–disorder transition in triethylenediamine has been investigated by Raman spectroscopy. Large increase in linewidth accompanied by discontinuous decrease in the mode frequencies are observed across the transition to the disordered cubic phase at 351 K. Except for a few modes, the magnitude of discontinuity in frequency is much less compared to that expected for the given volume change. Most of the doubly degenerate modes show abrupt increase in linewidth at the transition temperature, which is understood to be due to dynamic disorder in the cubic phase.