Stanford Synchrotron Radiation Lightsource

Speaker: Dr. Hong-Guang Duan

Program Description
The process of funneling the absorbed photon energy within the chlorophyll antennae system of photosynthetic systems was a critical evolutionary turning point in living systems. We have studied the ultrafast energy and charge transfers in PSII reaction centre complex by employing two-dimensional (2D) electronic spectroscopy [1]. We uncovered the timescales of energy/charge transfers and decay of electronic quantum coherences at low temperature. Based on data analysis, we disentangled the long-lived vibrational coherences from the electronic coherence. Moreover, we also developed the 2D circular dichroism spectroscopy to investigate the transient chiral dynamics in PSII reaction centre. Based on its symmetric pigment arrangement, we uncovered the transient chirality-related population transfers in pigments along its central axis [2, 3]. We also studied the excited-state dynamics and associated electronic/vibronic quantum coherences by 2D spectroscopic approach and explored the detailed structural change and of matter by ultrafast electron diffraction. The combination of spectroscopic and diffractive approaches could provide a complete picture of excited-state dynamics of matter.
References:
[1] A. Jha, P. -P. Zhang, V. Tiwari, L. Chen, M. Thorwart, R. J. D. Miller, and H. -G. Duan, Unraveling quantum coherences mediating primary charge transfer processes in photosystem II reaction center. Science Adv. 10, adk1312 (2024).
[2] Y. Yang, et al. Diverse Transient Chiral Dynamics in Evolutionary Distinct Photosynthetic Reaction Centers. J. Chem. Theo. Comp. 21, 321 (2024).
[3] Z. -H. Liu, A. Jha, X. -T. Liang, and H. -G. Duan, Transient Chiral Dynamics in the Fenna-Matthews-Olson Complex Revealed by Two-dimensional Circular Dichroism Spectroscopy. J. Phys. Chem. Lett. 15, 6550 (2024).