INFRARED-SPECTRA OF SOLID CHLORODIFLUOROMETHANE

Infrared spectra of solid chlorodifluoromethane (CHClF2 or Freon 22) a t temperatures between 12 and 105 K are presented and discussed. The e vidence for a reversible solid state phase transition at (55 +/- 5) K is described, confirming the results of a previous Raman study. Two me tastable phases are also detected. Multiplet structure is observed for all nine internal modes and interpreted in terms of crystal field eff ects. This confirms that both phases are ordered, with rather large un it cells, and that the transition is of a displacive type. Coincidence s with Raman frequencies suggest that both structures are probably non -centrosymmetric. The lattice spectra are compatible with these conclu sions and are tentatively assigned on the basis of inertia and intensi ty arguments.