The factor group splittings in the molecular vibrations of crystalline phenol

Evidence for dynamic coupling in the molecular vibrations of crystalline phenol, a hydrogen bonded polymer, has been obtained for the first time. The factor group splittings in the vibrational spectra are resolved and interpreted on the basis of the orthorhombic symmetry approximation of the space group. The crystal frequencies are classified into symmetry species B1 and B2 of the D2 factor group, having dipole moment vectors along the crystal axes a and b, respectively. The relation between the polarization behavior of the multiplet components and the symmetry species of the internal modes has been established. Some of the vibrational assignments are discussed.