Polarized Emission and Triplet—Triplet Absorption Spectra of Aromatic Hydrocarbons in Benzophenone Crystals

The polarization of the phosphorescence of naphthalene, anthracene, pyrene, and chrysene as guest in the benzophenone lattice have been examined. Considerable out-of-plane intensity has been shown to be present in these transitions. The results have confirmed conclusions from previous experimental observations and have led to certain assignments for the lowest triplet states which are in agreement with theoretical predictions. The triplet—triplet absorption spectra of naphthalene, anthracene, and chrysene have been detected using polarized light and the mixed crystals. All these T—T transitions were polarized in the aromatic molecular planes, in accordance with theory. The phosphorescence of pyrene in benzophenone has been analyzed and tentatively interpreted as triplet—singlet emission of the pyrene dimer.