Location: SCL 160
Join the Yale Chemistry Department for a Physical Chemistry seminar with Minjung Son, postdoctoral researcher from the University of Wisconsin-Madison.
Abstract:
In light harvesting, solar energy is captured by arrays of coupled chromophores and then funneled towards the site of energy conversion. A major roadblock in mapping the pathways of energy transfer had been that most previous experiments measured only a narrow portion of the broad solar spectrum captured by light-harvesting systems. I will present the development of ultrabroadband 2D electronic spectroscopy, an ultrafast spectroscopic tool that enables mapping of energy flow across the visible and the near-infrared range, and how this technique enabled the discovery of previously inaccessible photophysics in natural and synthetic light-harvesting systems. First, I will present the elucidation of pathways responsible for photoprotection of green plants against excess sunlight. In the major light-harvesting protein of green plants, LHCII, I directly resolved a sub-picosecond photoprotective chlorophyll-to-carotenoid energy transfer process, which had only been theoretically proposed. By introducing a systematically controllable near-native membrane platform that mimics the plant membrane, I also determined the previously inaccessible impact of physiological parameters such as protein crowding and protein-lipid interaction. I will then discuss another application where a new type of light-matter interaction, known as polaritons, is used as a means to manipulate the dynamics of energy flow in semiconducting carbon nanotubes. Formed by strong coupling between photons and molecules, polaritons enable a plethora of new photophysics, such as long-range energy transfer, the presence and mechanism of which, however, had not been elucidated. A combination of ultrabroadband 2D measurements and quantum calculations revealed the spectroscopic signatures of the hypothesized long-range energy transfer as well as its underlying mechanism, which involves an intricate interplay between light-matter coupling and molecular parameters.
About Minjung Son:
Minjung Son earned her Ph.D. in 2020 at the Massachusetts of Institute of Technology as a Robert T. Haslam Presidential Fellow. Working with Prof. Gabriela Schlau-Cohen, she investigated the photophysical mechanisms of light harvesting and photoprotection in the photosynthetic antenna proteins of green plants by developing an ultrabroadband two-dimensional electronic spectroscopy technique. Minjung is currently a postdoc in the group of Prof. Martin Zanni at the University of Wisconsin-Madison. Her current research interests lie on the interface of materials science, physical chemistry, and optical spectroscopy, where she focuses on understanding the photophysics of energy transport in organic nanomaterials and exciton-polaritons using ultrafast spectroscopy and microscopy. Her contributions were recognized with the 2021 Justin Jankunas Dissertation Award in Chemical Physics from the American Physical Society and the 2022 PHYS Young Investigator Award from the American Chemical Society.