Photosynthetic processes span a significant range of time scales from ultrafast photon absorption and charge separation to gradual light acclimation processes. In order to develop a comprehensive understanding of photosynthetic regulation, it is necessary to connect these disparate timescales, which can pose a challenge for experimentalists. In an effort to monitor ultrafast (fs-ns) events over slow timescales (sec-min), our lab has developed several types of “snapshot” spectroscopy. These techniques allow us to develop a better understanding of how to connect experimental observations to the timescale over which plants and algae experience changes in solar radiation in the environment, thereby informing future efforts to improve photosynthesis and crop yields.
Fluorescence lifetime snapshots allow us to monitor the chlorophyll excited state lifetime throughout the process of illumination by high intensity white light, which can provide information about the magnitude and timescale of quenching. Similarly, snapshot transient absorption (TA) spectroscopy is able to track the charge transfer and/or excitation energy transfer quenching mechanisms, which can provide evidence for the involvement of and timescales over which specific molecular species participate in quenching. We are currently developing additional snapshot techniques to further enhance our understanding of photosynthetic regulation processes.
Snapshot transient absorption spectroscopy: toward in vivo investigations of nonphotochemical quenching mechanisms. S. Park, C. J. Steen, A. L. Fischer, G. R. Fleming, Photosynthesis Research (2019).
Chlorophyll-Carotenoid Excitation Energy Transfer in High-Light-Exposed Thylakoid Membranes Investigated by Snapshot Transient Absorption Spectroscopy. S. Park, A. L. Fischer, C. J. Steen, M. Iwai, J. M. Morris, P. J. Walla, K. K. Niyogi, G. R. Fleming, Journal of the AmericanChemical Society, 140, 38, 11965-11973 (2018).
Snapshot Transient Absorption Spectroscopy of Carotenoid Radical Cations in High-Light-Acclimating Thylakoid Membranes. S. Park, A. L. Fischer, Z. Li, R. Bassi, K. K. Niyogi, and G. R. Fleming, J. Phys. Chem. Lett.8, 5548-5554 (2017).