Frenkel exciton scattering at microcrystallite surfaces caused by electric dipoles and monopoles Original Research Article

A theory of exciton scattering by electric charges located on microcrystallite surfaces is developed. The surface charges are assumed to be either electric monopoles or dipoles. When monopoles are present on microcrystallite surfaces, surface excitons are created in microcrystallites in which the sizes are larger than a critical value. On the other hand, when electric dipoles are present at microcrystallite surfaces, surface excitons are always created irrespective of the microcrystallite size. The theory is applied to explain the surplus exciton bandwidth observed in anthracene microcrystallites, which indicates the presence of surface scattering. The theory also predicts the presence of an additional and intense exciton absorption line which appears on the high-energy side of the host exciton absorption band.