Speaker: 
Jürgen Köhler - Universität Bayreuth

Title: 
Photophysics of Molecular Aggregates - Insights gained from single-object spectroscopy

Abstract:
Molecular aggregates are self-assembled supramolecular structures that feature interesting collective effects. In particular their photophysical properties such as the electronic transition energies, the transition-dipole moments, and the fluorescence lifetimes of the aggregate are distinctively different from the same parameters of the monomers. Thereby, the character of the electronically excited states depends crucially on the electronic coupling of the monomers, i.e. on the mutual distances and orientations of the molecular building blocks which is dictated by the molecular packing. However, in non-ordered (crystalline) samples distinctive spectral signatures that are characteristic for specific structural features might be lost in ensemble-averaged spectra due to the intrinsic heterogeneity of the soft samples. The problem can be mitigated by applying single-molecule techniques.

In a more generic part the talk will intoduce the theoretical concepts for describing the electronically excited states of molecular aggregates and then discuss some experimental examples of aggregates with different geometries.

- - -
QuCoLiMa Talks are regular seminars of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter), where (external) experts are invited to present their work.

More information at www.qucolima.de/talks