The low energy density of solar radiation necessitates dense packing of the light absorbing components (chromophores) of the light harvesting system of photosynthetic organisms. The close spatial proximity of the chromophores, chiefly chlorophyll or bacteriochlorophyll, leads to new electronic structure, dynamics, and emergent properties of the light harvesting system. In this talk, I will discuss how the interaction of structure, energetics and dynamics leads to the ability to transfer excitation between hundreds of chromophores en route to the photochemical reaction center with near unit quantum efficiency at low light levels. I will discuss the recent work demonstrating the existence of quantum coherence effects, the possible functional role of coherence, and the origin of the observed decoherence.

Graham Fleming currently serves as UC Berkeley ’s Vice Chancellor for Research, a position which he assumed in April 2009. Fleming served as the Deputy Director of Lawrence Berkeley National Laboratory from 2005 through 2007. Through joint appointments as Melvin Calvin Distinguished Professor of Chemistry at UC Berkeley, and Founding Director of both the Berkeley Lab’s Physical Biosciences Division and UC Berkeley’s California Institute for Quantitative Biosciences (QB3), he has re-shaped the intersection of physical and biological sciences, while maintaining his own investigations into ultrafast chemical and biological processes, in particular, the primary steps of photosynthesis. Throughout his administrative career, Fleming has remained a highly active scientific researcher. He has authored or co-authored more than 400 publications, and is widely considered to be one of the world’s foremost authorities on ultrafast processes. In addition to his many other activities, Fleming has given numerous talks around the world on the inter-relation and inter-complexity of energy, climate and photosynthesis. In 2007, Fleming led the effort (with co-chair Mark Ratner) to define Grand Challenges in Basic Energy Science for DOE/BES, resulting in “Directing Matter and Energy: Five Challenges for Science and the Imagination.”