Berlin 2005 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 68: Laserspektroskopie II
Q 68.4: Vortrag
Mittwoch, 9. März 2005, 11:45–12:00, HU 2014a
Investigation of excitation dynamics in Acaryochloris marina by picosecond fluorescence spectroscopy — •Franz-Josef Schmitt1, Joachim Huyer1, Hans Joachim Eichler1, and Hann-Jörg Eckert2 — 1Optisches Institut - P 1-1, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin — 2Max-Volmer-Laboratorium, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin
The primary processes of photosynthesis in higher plants and cyanobacteria start with the generation of excited states by light absorption within pigment-protein complexes forming the antenna system. The electronic excitation then migrates via singlet-singlet energy transfer to the reaction center where it induces a primary charge separation leading to a primary radical pair (P+A-). Up to quite recently it was assumed that the chlorophyll-antennae of oxygenic photosynthetic organisms contain mainly Chl b and Chl a. Therefore the discovery of the cyanobacterium Acaryochloris marina attracted much attention in the scientific community because its antenna system contains mainly Chl d and phycobiliproteins and only small amounts of Chl a. The nature of the primary donor of PS II of A. marina (Chl a or Chl d) is still a matter of discussion. The Qy absorption band of Chl d is shifted towards longer wavelengths with respect to Chl a. This spectroscopic property raises important questions about the mechanism of excitation energy transfer. In this report we study the excitation energy transfer within the antenna of Acaryochloris marina by measuring the ps-fluorescence dynamics after excitation of whole cells with laser pulses of various wavelengths.