Phonon spectrum of a fluorene molecular crystal

Abstract

The dynamics of the fluorene molecular crystal lattice is calculated by the atom-atom potential method. The fundamental lattice vibration frequencies are determined, their assignment is made, and shapes of the vibrations are studied over a pressure range of from 1 bar to 30 kbar. For acoustic phonon vibrations, the distribution of Debye frequencies over directions of the wave vector is estimated. The results obtained are used to discuss the photochemical reaction of detachment of a hydrogen atom in a fluorene crystal, a process occurring by the tunneling mechanism.