Critical behaviour of the light scattering intensity at the phase transitions in hexammine cadmium (II) halides

Abstract
A preliminary investigation is reported on the Raman spectra of hexammine cadmium (II) halides above and below their phase transition temperatures. The spectra indicate that both dynamic and static changes occur at the phase transitions. Critical effects of the light scattering intensity of internal modes involving NH3 motion, which occur, provide direct evidence that ordering of the NH3 groups begins at Tc is approached from above, and that these transitions are orientational in nature with an accompanying static distortion.