Starts 28 Apr 2016 11:30
Ends 28 Apr 2016 12:30
Central European Time
Abstract: One of the most surprising and significant advances in the study of the photosynthetic light-harvesting process is the discovery that the electronic energy transfer might involve long-lived electronic coherences, also at physiologically relevant conditions. Central to these discoveries has been the development of new ultrafast spectroscopic techniques, in particular two-dimensional electronic spectroscopy (2DES), which is now the primary tool to obtain clear and definitive experimental proof of such effects [1]. A crucial point now is to understand the origin and the relevance of such long-lived quantum coherences in transport processes that seem to be strongly related to the complex interplay between electronic and vibrational degrees of freedom [2]. With the aim of clarifying how different vibrational modes influence the mechanisms and the dynamics of energy migration, we focused our attention on simplified bio-mimetic model systems. We suitably designed, prepared and spectroscopically characterized different multi-chromophoric systems characterized by different interpigment distance and electronic coupling. The results obtained applying 2DES to these three samples and the comparison with the ones obtained on the corresponding monomeric forms allowed isolating and identifying contributions to the nonlinear signal associated with inter-exciton dynamics (electronic coherences) from vibrational dynamics. The results allow suggesting possible future guidelines for the design of artificial light-harvesting systems where energy migration is effectively driven by quantum mechanics. [1] E. Collini, Chem Soc Rev 42, 4932-4947 (2013). [2] A.W. Chin, et al., Nature Phys 9, 113-118 (2013).