Lattice dynamics and praphase in N-bensylanyline crystals

N-benzylanyline single crystals are grown, and X-ray diffraction probing of their structure allows their symmetry to be attributed to the C_2h.⁵ phase. Polarized Raman studies of these crystals allow the frequencies of lattice phonons to be estimated and their symmetry to be established. The abnormal behavior of the two lowest-frequency A_g symmetry soft modes, the condensation of which is not detected below the melting point (36–38°C), is noted. The possibility of a high-temperature virtual phase transition and praphase is discussed. Theory group consideration of the praphase allows determination of its symmetry and the symmetry of phonons related to the virtual phase transition.