Polarized absorption and emission of ordered self-assembled porphyrin rings

Self-assembled rings (with diameters of 0.1-2.0 mum) consisting of porphyrin dodecamer molecules are formed by evaporating chloroform solutions on glass substrates. Fluorescence microscopy experiments on individual rings reveal a strongly polarized optical absorption and emission. Quantitative analysis of the fluorescence images evidences the high degree of order within the rings, consisting of radially oriented columnar stacks of porphyrin dodecamers, and the absence of energy transport along the rings on length scales resolved by fluorescence microscopy.