Speaker
Description
Living organisms are much more than the sum of their parts, and understanding how they work requires studying them over a vast range of time and length scales. Photosynthesis beautifully illustrates the challenges inherent in studying biological systems: on a femtosecond to picosecond time scale, light energy absorbed by a photosynthetic antenna complex is transferred through a maze of antennas to a “reaction center” where it is stored as stable charge separation that fuels the downstream processes of biomass production. While an isolated chlorophyll pigment will absorb sunlight, a photosynthetic complex achieves entirely new functionality through exquisite control of the local pigment environment and the relative spacing and orientation of the constituent pigments, tailoring the energy landscape to orchestrate, in time and space, the energy transfer and charge separation events that underlie photosynthesis. To capture the fastest dynamical processes in biology, coherent multidimensional spectroscopies (CMDS) provide the ability to initiate synchronized biological function in an ensemble of molecules, and monitor, with exquisite time resolution, the system evolution via its response to a carefully timed sequence of laser pulses. I will demonstrate how multidimensional spectroscopies can address open questions about photosynthetic systems and describe our recent progress in developing and using these tools to probe the mechanisms of ultrafast energy conversion in natural photosynthetic systems.