Raman spectra of bismuth trihalides in the solid and liquid states

Raman spectra were measured for BiBr3 and BiCl3 in the polycrystalline and liquid phases. A new assignment for BiBr3 is proposed on the basis of the temperature dependence of the Raman spectra. An abrupt spectral change originating from an order‐disorder phase transition was observed in BiBr3. In the liquid phase, both compounds showed a very broad composite spectra in the Bi–X stretching vibration region, which can be understood as originating from a mixture of multiply charged bismuth halide complexes in addition to the monatomic halide anions.