[Aspuru-Guzik group list] Fwd: Talk of possible interest to Center for Excitonics

Alán Aspuru-Guzik | Professor of Chemistry and Chemical Biology Harvard University | 12 Oxford Street, Room M113 | Cambridge, MA 02138 (617)-384-8188 | http://aspuru.chem.harvard.edu | http://about.me/aspuru ---------- Forwarded message ---------- From: Justin Caram &lt;jcaram(a)mit.edu&gt; Date: Tue, Jun 23, 2015 at 8:55 AM Subject: Talk of possible interest to Center for Excitonics To: &quot;efrc-faculty(a)mit.edu&quot; &lt;efrc-faculty(a)mit.edu&gt;du>, &quot;excitonics-sp(a)mit.edu&quot; < excitonics-sp(a)mit.edu&gt; Hi all, I invited a former labmate of mine to give an informal talk. It may be of interest to members of the center. It will be this Friday (June 26) at 11:00 in 6-321 (Moore Room). Here is the abstract. --Justin Caram ________________________________ Two-Dimensional Electronic Spectroscopy In Highly Scattering Media Reveals Energy Transfer Events In Living Rhodobacter sphaeroides Efficient exciton transport over large distances through polymer networks is an open problem in chemistry with applications to solar harvesting, and efficient lighting. However, photosynthetic organisms routinely perform exciton transport over distances greater than 100 nm with nearly 100% quantum efficiency. Furthermore they exhibit real time control over energy transfer pathways in order to both optimize light harvesting and protect the organism from excess excitation. Understanding the design principles within photosynthetic energy transfer begins with the ability to observe these ultrafast processes in living organisms. I will present advances in two-dimensional electronic spectroscopy (2DES) that permit the acquisition of 2DES signals in the presence of intensely scattered light. These advances have made possible the observation of energy transfer at room temperature in living cells of Rhodobacter sphaeroides, a purple bacterium known for its high quantum efficiency. Timescales of 50 fs - 200 ps are recovered in a single experiment exhibiting both intra and inter complex relaxation and transfer. Further 2DES experiments done in fast succession (~ every 15 min) were performed to capture real time changes to the energy transfer pathways in response to oxygen and intense light.