Spectroscopic studies of interaction and dynamics in the naphthalene: Perfluorobiphenyl crystalline complex

Abstract

Raman and electronic emission spectroscopy are used to study the interaction and the dynamics in a new 1 : 1 binary crystalline complex between naphthalene and perfluorobiphenyl. Raman spectra are obtained in the regions of both phonons and intramolecular vibrations. The result of this study shows that the naphthalene: perfluorobiphenyl complex is stabilized by weak van der Waals forces, yet it is a highly ordered crystalline complex. The complex has an unusual geometry in which naphthalene is planar while the perfluorobiphenyl molecule is nonplanar. Isotopic substitution with respect to naphthalene shows that the phonon bands in this complex are dynamically decoupled, which is expected from the differences in the mass coefficients of the two molecules. In the complex the lowest electronic states of both singlet and triplet multiplicities are that of naphthalene. The exciton interaction and the exciton-phonon coupling are found to be weak for both the singlet and the triplet excited electronic states.