Infrared Spectra in Polarized Light and Vibrational Assignment of the Infrared-Active Modes of Pyrene and Pyrene-d10

Abstract

The infrared spectra of pyrene and pyrene‐d₁₀ in the crystalline state and in solution of various solvents were measured between 4000 and 400 cm^‐1. Spectra in polarized light with the electric vector of the incident light vibrating in the ab crystal plane were obtained from both single crystals and oriented polycrystalline samples. Spectra in polarized light with the electric vector in the ac crystal plane were also obtained from oriented films. The comparison of the experimental dichroism with the predictions based on the knowledge of the crystal structure allowed an almost complete assignment of the fundamental modes of vibrations active in the ir spectrum.