Vibrational spectroscopy of molecular crystals

The use of vibrational spectroscopy in the study of structures, molecular motions and intermolecular forces in molecular crystals is described. A brief outline of the perturbation theory is followed by mention of the advantages of the infrared absorption, reflection and Raman spectroscopic methods. Effects of crystalline symmetry on vibrational spectra, the use of polarized light in studying symmetry and in vibrational assignment, direct determination of intermolecular force parameters from crystal splittings, relations between intermolecuiar forces and lattice vibrations, and spectroscopic changes occuring on change of phase are discussed in illustration of the value of vibrational spectra