Investigating the ultrafast dynamics of natural and artificial light harvesting

Plants, algae and certain bacteria efficiency capture the abundant sunlight incident on the Earth to drive photosynthesis- the process of converting carbon dioxide and water into simple sugars used for plant growth. Whilst a macroscopic understanding of natural photosynthesis has been established, microscopic details that underpin the so-called "design principles" of photosynthesis have yet to be fully detailed. Several roles for the protein that encapsulates the light harvesting chlorophyll moieties are recognised, but the specific molecular interactions between chlorophyll and protein residues that give rise to their unique bath response have eluded experimental studies. Model proteins with known x-ray crystal structures, that contain only one or two visible chromophores will be investigated to reveal the "bath" dynamics of the protein as a function of the binding residue and protein pocket.

Man-made efforts to efficiency harness the solar flux have been far less effective, with relationships between the molecular structure and overall power conversion efficiencies only starting to emerge for a plethora of materials such as organic bulk-heterojunctions or semi-conducting materials. In all instances, the absorbed light is used to induce charge separation into electrons and holes, but the mechanism and location for such processes remain nebulous.

Ultrafast multidimensional optical spectroscopies such as 2D electronic spectroscopy will be used to explore these phenomena, creating a map of energy flow between constituent molecules with femtosecond time resolution (1 fs = 1 millionth billionth of a second).