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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1800
DTSTART:20100309T170000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T131633Z
LAST-MODIFIED:20100226T155930Z
LOCATION:5310 Chamberlin
SUMMARY:Ultrafast physics in photosynthesis: Mapping sub-nanometer ene
 rgy flow\, R. G. Herb Condensed Matter Seminar\, Naomi Ginsberg\, Lawr
 ence Berkeley National Laboratory
DESCRIPTION:In the first picoseconds of photosynthesis\, photoexcitati
 ons of chlorophyll molecules are passed through a network of chlorophy
 ll-binding proteins to a charge transfer site\, initiating the convers
 ion of absorbed energy to chemical fuels.  The remarkably high quantum
  efficiency of this energy transfer relies on near-field coupling betw
 een adjacent chlorophyll molecules and their interaction with protein 
 phonon modes.  Using two-dimensional electronic spectroscopy\, we trac
 k the time-evolution of energy flow in a chlorophyll-protein complex\,
  CP29\, found in green plants.  The results from these nonlinear four-
 wave mixing experiments elucidate the role of CP29 as a light harveste
 r and energy conduit by drawing causal relationships between the spati
 al and electronic configurations of its chlorophyll molecules.  Throug
 h independent control of experimental light pulse polarizations\, we h
 ave furthermore developed a technique to determine the relative angles
  between the transition dipole moments responsible for energy transfer
 .  This work not only yields tools for structural and spectral molecul
 ar characterization\, but also deepens our understanding of how photos
 ynthetic systems have evolved to optimize the conversion of light to b
 iomass.
URL:https://www.physics.wisc.edu/events/?id=1800
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