Superradiance of surface-organized molecules

Adsorption on well-defined surfaces provides a unique possibility to arrange fluorescent molecules in long-range ordered two dimensional aggregates with structures different to those of bulk net planes. This results in different and partly novel optical properties of the molecules compared to those of the respective crystals. We demonstrate this for PTCDA adsorbed on the KCl(100) surface. Due to delocalization of the optical excitation in the aggregates strong superradiant fluorescence occurs. The strength of the superradiance is related to the level of delocalization and thus the aggregate size, which we can measure by diffraction techniques. We demonstrate this correlation and its impact on the line shape and width in the optical spectra.

[1] M. Müller, A. Paulheim, A. Eisfeld und M. Sokolowski, J. Chem. Phys. 139 (2013) 044302.