[MOS] Today- Modern Optics and Spectroscopy Seminar with Minjung Son

[Michelle Contos]

There will be a Modern Optics and Spectroscopy Seminar held today in 34-401A<http://whereis.mit.edu/?go=34> at 12pm


Minjung Son

MIT—Schlau-Cohen Group

“Mapping out pathways of light harvesting and photoprotection in plants with ultrabroadband two-dimensional electronic spectroscopy”

Plants harness energy by absorbing light across the visible region of the solar spectrum and then rapidly and efficiently funneling the energy towards the reaction center. Previous experiments to understand the mechanisms by which energy relaxes across this large energy gap have been limited to the dynamics of the low-energy states, leaving the higher-lying states, including how they transfer energy downhill, unexplored. I will describe the development of an ultrabroadband two-dimensional (2D) electronic spectrometer that enables us to map out the pathways of energy flow in light-harvesting complex II (LHCII), the major antenna complex of plants, across the visible region. The 2D spectra show that one of the carotenoids, lutein 2, plays a central role in mediating light harvesting by accepting energy from higher-lying states and funneling it downhill via two parallel pathways, including a non-adiabatic transition into a dark state.

In parallel with the light-harvesting pathways, plants have evolved pathways to protect against photooxidative damage, where harmful energy is rapidly dissipated as heat. While the photophysical mechanism of dissipation has been widely debated, previous experiments lacked the spectral and temporal requirements to characterize the ultrafast timescales and large energy gaps involved. Using ultrabroadband 2D electronic spectroscopy, I directly resolve a dissipative chlorophyll-to-carotenoid energy transfer pathway, which had been hypothesized yet previously unobserved. Furthermore, I will show that the amplitude of this dissipative pathway is sensitive to the local environment, which may be used to control the subtle balance between light harvesting and photoprotection in vivo.


Refreshments will be served immediately following the seminar!


Michelle Contos
Administrative Assistant
Massachusetts Institute of Technology
Department of Chemistry
77 Massachusetts Ave, 6-333
Cambridge, MA 02139
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