Optical Anisotropy of Anthracene Single Crystals for Photon Energies from 4.5 to 11.5 eV

Reflection spectra between 4.5 and 11.5 eV were measured for near normal incidence (7.5°) with s‐polarized light from the (001) and (010) plane of anthracene single crystals at room temperature. The strong molecular 1 B 2u transition causes a strong anisotropic reflection band from the (010) face. By a Kramers‐Kronig analysis ε 2 spectra have been obtained for the most important polarization directions. The Davydov splitting for the prominent excitation at approximately 4.5 eV, taken for polarization directions where no longitudinal contributions to the interaction lattice sums are present, is smaller than 0.05 eV. There is evidence, that a transition starting at 7.05 eV is polarized perpendicular to the molecular plane.