Rayleigh and Brillouin Scattering in RbH₃(SeO₃)₂ near the Phase Transition Temperature

Abstract

Rayleigh and Brillouin scattering spectra of RbH₃(SeO₃)₂ have been observed around the phase transition temperature T_C. The temperature dependence of the Brillouin frequency shifts shows a small anomaly near T_C in all three principal directions. The sound-velocity dispersion is found only in the c₅₅ transverse mode. The intensity of the Rayleigh component is insensitive to temperature even just near T_C. The existence of dynamic clusters above T_C is discussed and its characteristic frequency is roughly estimated, while static clusters are concluded not to exist in the same temperature region.