``Excimer'' and ``Defect'' Structure for Anthracene and Some Derivatives in Crystals, Thin Films, and Other Rigid Matrices

The emission lifetimes of matrix-stabilized dimers of anthracene and its derivatives were observed. The two principal conformations considered were the sandwich excimers and the 55° dimers. The excimer lifetimes may be of use in establishing wavefunctions for these transient states. A comparison of the lifetimes and emission structure from the dimers in rigid solvents with the time and wavelength structure of emission from strained crystals permits identification of a crystal defect in anthracene. The variable structure of anthracene thin films was demonstrated and partially identified.