Interpretation of the vibrational spectrum of crystalline phenanthrene

Abstract

Couplings between inter- and intramolecular vibrations have been investigated. In normal-mode calculations a program has been used which allows all possible couplings between molecular and crystal vibrational modes. Several low-frequency molecular modes coupled to lattice vibrations have been isolated. A complete assignment of the phenanthrene crystal spectrum is presented and the intermode mixing occurring in the region from 1550 to 1250 cm−1 is discussed.