Dipole–dipole interactions and Raman line shape of IR active modes of CX4 molecules in disordered phases

The influence of strong induced dipolar interactions on the Raman spectrum of the ν3 vibration of CX4 molecules is discussed in the case of dense, disordered phases. For CF4, in its plastic and its liquid phases, we show that the very peculiar two maximum spectrum can be completely reproduced by a numerical calculation which introduces only a point dipole interaction model. On the other hand, the experimental broad but featureless spectrum of CBr4 in its plastic phase cannot be explained without taking into account the high polarizability of the Br atom.