BPCPPDYSOE21 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 12: Single Molecule Biophysics I
BP 12.2: Vortrag
Dienstag, 23. März 2021, 09:30–09:50, BPa
Electronic Quantum Coherence in Photosynthetic Protein Complexes — Hong-Guan Duan Duan1, Ajay Jha1, Vandana Tiwari1, Richard J. Cogdell2, Khuram Ashraf2, Valentyn I. Prokhorenko1, •Michael Thorwart3, and R. J. Dwayne Miller4 — 1Max Planck Institute for the Structure and Dynamics of Matter, Hamburg — 2Institute of Molecular, Cell & Systems Biology, University of Glasgow, UK — 3I. Institut für Theoretische Physik, Universität Hamburg, Germany — 4University of Toronto, Canada
The search for quantum effects in biological systems led previous experiments to report long-lived electronic quantum coherence in the primary step of the energy transfer in photosynthetic protein complexes. However, the origin of the coherence became a topic of intense debate. We have revisited this in a joint experimental and theoretical effort studying the quantum dynamics in the Fenna-Matthews-Olson (FMO) complex by two-dimensional electronic spectroscopy at different temperatures. We found that the electronic coherence time is significantly shorter under ambient conditions than previously reported. To capture solid evidence of quantum coherence, lower temperatures are required. We have clearly observed electronic coherence with a time scale of 500 fs at low temperature (20 K). However, the coherence lifetime is rapidly reduced with increasing temperature. At room temperature, electronic coherence is too short (60 fs) to play any functional role in the energy transfer which occurs on a time scale of picoseconds. The long-lived oscillations previously reported in 2D spectra are due to Raman vibrational modes on the electronic ground state.