Elementary excitation in photosynthetic purple bacteria : How big is it?

Summary, in English

We have studied excitation energy transfer in the photosynthetic antenna
systems LH1 and LH2 of purple bacteria. Femtosecond pump-probe
experiments were combined with computer simulations using the recently
established structure of these systems to assess the nature of
electronic excitation. We have measured the transient absorption
kinetics and spectra of the LH1 and LH2 complexes in the temperature
range from 4.2 K to 296 K with femtosecond time resolution. The Pauli
master equation approach suggests that experimentally measured
population and anisotropy kinetics in LH1 and LH2 cannot be described as
a simple hopping between bacteriochlorophyll (BChl) a molecules.
Exciton calculations where also monomeric doubly excited states are
included indicate that the coherence length of the excited state is
about 4 BChl a molecules at room temperature and it increases if
temperature is lowered. Experiments where segments of LH1 antenna with
different sizes were used suggest that the upper limit for the coherence
length at 4 K is 12 BChl a molecules.

• Author: M. Chachisvilis; T. Pullerits; W. Westerhuis; C. N. Hunter; V. Sundström
• Editor: Paul F. Barbara; James G. Fujimoto; Wayne H. Knox; Wolfgang Zinth
• Department/s: Chemical Physics
• Publishing year: 1996
• Language: English
• Pages: 314-315
• Publication/Series: Springer Series in Chemical Physics
• Volume: 62
• Links: http://dx.doi.org/10.1007/978-3-642-80314-7_136
• Document type: Conference paper
• Publisher: Springer
• Topic: Atom and Molecular Physics and Optics
• Status: Published
• ISBN/ISSN/Other: ISSN: 0172-6218; ISSN: 2364-9003; ISBN: 978-3-642-80314-7; ISBN: 978-3-642-80316-1