Part II: Extracting Photochemical Design Principles from Biological Systems in vivo

Natural light-harvesting systems, such as photosynthetic pigment-protein complexes, efficiently transfer energy through space with high efficiency. Ultimately, we would like to understand the design principles nature evolved to improve optoelectronic devices that rely on light harvesting and energy transfer, such as solar cells. We perform ultrafast 2D electronic spectroscopy measurements on a variety of systems ranging from the Fenna-Matthews-Olson antenna complex isolated from green sulfur bacteria to in vivo cyanobacteria. We observe larger amplitude coherences under reductive conditions that mimic the chemistry of the complex in vivo. We can use spectroscopic tools that allow us to follow the energy in both space and time. In particular we can correlate the existence of quantum coherences, particularly those involving excited electronic states, with faster, more efficient energy transfer, and assessing the role of the ground and excited states in the transfer process. Future work will look at the how changing light conditions influences the complex chemistry in the photosynthetic membranes, ultimately affecting the energy transfer processes.