Abstract
The ferroelastic phase transition in sym-triazine C3N3H3 has been investigated by means of Brillouin scattering and correlation spectroscopy. Soft TA modes are observed by Brillouin scattering but a well-defined central peak could not be found. Near the transition in the high temperature phase a 50% increase in Rayleigh intensity is found. No correlation function was observed in the time domain between 1 and 10 -6 s. These results are discussed by a Landau mean field theory and dynamical rotation-translation coupling theory. © 1982 American Institute of Physics.