Excitons in photosynthetic purple bacteria : Wavelike motion or incoherent hopping?

Summary, in English

We have studied excitation energy transfer in the photosynthetic antenna
systems LH1 and LH2 of purple bacteria. Femtosecond pump−probe
experiments are combined with computer simulations using the recently
established crystal structure of these systems to assess the nature of
excitation motion. We have measured the transient absorption kinetics
and spectra of the LH1 and LH2 complexes in the temperature range from
4.2 to 296 K with femtosecond time resolution. The calculations based on
the Pauli master equation disagreed with experimentally measured
population and anisotropy kinetics, suggesting that the simple model of
excitation hopping between bacteriochlorophyll a molecules is not
a proper description for energy transport in LH1 and LH2. As a next
step we have used the exciton theory to reproduce the transient
absorption spectra of LH2, and we found that the coherence length of the
exciton in B850 of LH2 1.5 ps after excitation of B800 is 4 ± 1.

• Author: Mirianas Chachisvilis; Oliver Kühn; Tõnu Pullerits; Villy Sundström
• Department/s: Chemical Physics
• Publishing year: 1997-09-11
• Language: English
• Pages: 7275-7283
• Publication/Series: Journal of Physical Chemistry B
• Volume: 101
• Issue: 37
• Links: http://dx.doi.org/10.1021/jp963360a
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Physical Chemistry (including Surface- and Colloid Chemistry)
• Status: Published
• ISBN/ISSN/Other: ISSN: 1520-6106