A Raman spectroscopic study of naphthalene: octafluoronaphthalene at high pressure and low temperature

Abstract

The crystalline 1:1 complex naphthalene:octafluoronaphthalene has been investigated at high pressure under ambient temperature, and down to 10 K at ambient pressure, by Raman spectroscopy. The complex is stable in the pressure range studied, 1 to 80 kbar. The lattice mode frequencies show a strong positive pressure dependence, while the internal modes are only weakly affected. The temperature and pressure dependencies of the phonon frequencies suggest that the bonding interaction between the molecular partners is of the usual van der Waals type, and the results are in agreement with the ‘‘sublattice’’ model proposed by Chen and Prasad. The mode Grüneisen γ_i’s have been obtained from the pressure data. From the measured (∂ν/∂T)_p and (∂ν/∂P)_T, the ‘‘explicit,’’ ‘‘implicit’’ contributions have been extracted.