Two Dimensional Electronic-Vibrational Spectroscopy of LHCII Energy Flow and Initial Membrane Scale Simulations

Graham R. Fleminga, Nicholas H. C. Lewisa, Natalie L. Gruenkea, Thomas A. A. Oliverb, Matteo Ballottaric, Roberto Bassic
aDepartment of Chemistry, University of California, Berkeley, California 94720, United States Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States and Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States; bSchool of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom; cDipartimento di Biotecnologie, Facolt`a di Scienze, Universit´a di Verona, Strada Le Grazie, I-37134 Verona, Italia

Two dimensional electronic-vibrational (2DEV) spectroscopy is a new technique which has the potential to directly connect the time evolution of a set of energy levels (e.g. the excitons) to the time evolution of the site populations, in other words where the excitation is when. This “mapping” does not require assumptions on the excitations is when – the energy flow “movie”. I will describe the basis of the technique and its application to LHCII energy transfer dynamics. We are able to track Chl b to Chl a transfer with no ambiguities due to imprecise Hamiltonians or broad electronic linewidths. With definitive assignments of specific vibrational bands it is possible to track the motion of the energy through LHCII without relying on modeling or spectral fitting.

Regardless of how good the microscopic understanding of the energy transfer is, a full description of photosynthetic light harvesting and its regulation requires a membrane level understanding. I will briefly sketch 300 X 300 nm scale simulations of the grana membrane and their implication for fluorescence measurements.

Reference

J. Phys. Chem. Lett., 2016, 7 (5), pp 831–837. DOI: 10.1021/acs.jpclett.6b00037