IBS-CMSD Colloquium_Prof. Donatas Zigmantas(Lund University)(May 18, 2018)
IBS Center for Molecular Spectroscopy and Dynamics
COLLOQUIUM |
|
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SPEAKER
Prof. Donatas
Zigmantas (Chemical Physics, Lund University)
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TITLE
Revealing
the lowest states and excitation dynamics in bacterial photosynthetic reaction
centers
■ ABSTRACT
Light-harvesting
complexes in photosynthetic organisms absorb sunlight and transfer energy to
reaction centers (RCs), where the primary charge separation takes places.
Notably the general structural arrangement of RCs is preserved throughout
photosynthetic organisms and therefore many functional features of RCs are
expected to be similar. In all of the RCs the primary electron donor is the
special pair of chlorophyll-type molecules. It is tentatively assumed that the
lowest-energy state is the special pair exciton state often coupled to a
putative charge transfer state. However, despite numerous spectroscopic RC
studies carried out over the decades, uncertainties remain regarding the lowest
functional states in photosynthetic RCs. To study the lowest states in
bacterial photosynthetic RC we used two-dimensional electronic spectroscopy
(2DES) at cryogenic temperatures, which provides high spectral and time
resolution. Mapping the spectral signatures in two dimensions and following
their evolution in time enables unraveling otherwise congested transitions and
excitation dynamics. We employed 2DES at 77 K to investigate the lowest states
and their dynamics of the Q- type RC from purple non-sulfur bacteria [1] and
FeS-type RC from green sulfur bacteria [2,3]. The picture that we uncover is
more complex than what was thought before, as we observe functional involvement
of additional low energy states.
■ DATE AND VENUE
May 18, 2018 (Friday, 5:00 - 6:00 pm)
Seminar Room 116, KU R&D Center
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LANGUAGE
English
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INVITED BY
Director Cho, Minhaeng
*If you want to have dinner with Prof. Donatas Zigmantas or discuss with him, please contact Susan Tak (susan_tak@korea.ac.kr).