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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Electronic and Optical Properties of Organic Systems I

CPP 6.3: Vortrag

Montag, 22. März 2010, 12:15–12:30, H39

A new dimension in controlling ultrafast exciton dynamics of mesoscopic chromophore aggregates by fractal geometry — •Dmitri V. Voronine — Institut für Physikalische Chemie, Universität Würzburg, Würzburg, Germany

Ultrafast exciton percolation dynamics in mesoscopic chromophore aggregates was investigated using femtosecond transient absorption spectrometry. Ultrashort laser pulse excitation resulted in exciton-exciton annihilation whose rate depends on the spectral dimension of inhomogeneously broadened aggregates. The value of the spectral dimension and, therefore, the geometry of exciton percolation pathways can be controlled by varying the fractal aggregate geometry which is characterized by the fractal dimension. The fractal geometry dependence was shown for two types of porphyrin homo-aggregates: cationic (Pagg) and anionic (TPPS) porphyrins. The possibility to control the fractal and spectral dimensions of a porphyrin hetero-aggregate was also investigated. These results might be useful for the design of new materials for artificial light harvesting applications and for a better understanding of exciton dynamics in analogous systems such as conjugated polymers, carbon nanotubes, and others.