Prof. Dr. Jürgen Hauer
Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry
gives a talk on the subject:
Isolating Pure Donor and Acceptor Signals by Polarization-Controlled Transient Absorption Spectroscopy
Abstract:
Förster theory, an approximation valid in the limit of weak donor-acceptor coupling, is amongst the most useful and most extensively tested energy-transport theories. Peri Arylene dyads, as depicted below, are simple intramolecular donor-acceptor complexes, where the transition dipole moments of donor- and acceptor- moiety are nominally perfectly orthogonal. This means that electronic coupling between the moieties is small suggesting that the intramolecular energy transfer is well described by Förster theory. Experimentally, however, energy transfer is found to take place within a few- to a few tens- of picoseconds, in gross disagreement with the prediction of negligible transfer of Förster in theory. This discrepancy has alternatively been attributed to a wealth of competing theories, calling for experimental methods capable of providing more detailed insight into this clearly non-trivial transfer behavior. Here we employ polarization-controlled transient absorption (TA) with broadband detection to isolate individual parts of the total signal, providing a strategy to greatly reduce spectral congestion in complex systems. The aim is to facilitate detailed analysis based on tailored experimental methods. In the presentation, the same methodology will be applied to Bx and Qx,y transfer in chlorophyll a in solution.
Interested parties are cordially invited.
Prof. Stefan Lochbrunner