Absorption spectra of doped anthracene crystals. Determination of the direction of the transition moment of the dopant

Abstract

Measurements of the polarised guest absorption as a function of the angle of incidence in mixed molecular crystals lead to the determination of an effective transition dipole moment for the guest. Local field effects appear to be only slightly anisotropic. The two guest spectra produced by 2-aminoanthracene in anthracene are shown to correspond to different orientations of the transition moment. Computer simulation of the crystal packing leads to an assignment of the spectra to specific orientations of the guest molecule and so fixes the direction of the transition moment with respect to molecular axes.