Vibrational spectroscopy of solid state molecular dimers

The IR and Raman spectra of α- and β-perylene crystal vibrations are investigated, β-perylene is monomeric and α-perylene has face-to-face dimers. Frequencies and forms of the lattice vibrations as well as vibron relaxation and localization are discussed. Polarization ratios in α crystals are perturbed by coupling to dimer vibrations.