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1/17 - Faculty Candidate Seminar (physical): Daniel Turner, University of Toronto

Daniel Turner
University of Toronto
Host: Haw Yang

Do Coherent Dynamics Play a Role in Photosynthetic Energy Transfer?

Electronic energy transfer in molecular systems occurs over a range of timescales and under a variety of coupling conditions. Although energy transfer in photosynthetic proteins has been treated successfully using the Förster and Redfield models, recent experiments using two-dimensional electronic spectroscopy challenged these models and opened the door for improved treatments. An important subtopic in the study of electronic energy transfer is how intermolecular electronic coupling and intramolecular vibrations influence the response of the protein to optical excitation.

In this contribution, I will present transient-absorption and two-dimensional electronic spectra measured using femtosecond laser pulses that reveal coherent contributions to the measured dynamics in light-harvesting antenna proteins from cryptophyte algae. Analysis of the oscillations reveals the relative contributions from electronic and vibrational coherences.

A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. As a final topic, I will describe a new experiment, incoherent two-dimensional electronic spectroscopy, that can address the temporal incoherence component of this question.