The “Oriented Gas Model” and its Application to the Infrared Spectroscopy of Molecular Crystals

The real path of the polarized radiation in passing throughout an anisotropic crystal essentially depends on the orientation of the principal dielectric tensor axes with respect to the cleavage plane of the sample. Proper elucidation of this fact leads to new expressions for the dichroie ratio of a molecular crystal which contains terms connected both with the orientation of molecular transition moments and with the dielectric tensor axes as well. The agreement of the theory with experiment is illustrated in several examples.