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Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum
Verfasser / Verfasserin Thyrhaug, Erling ; Lincoln, Craig N. ; Branchi, Federico ; Cerullo, Giulio ; Perlík, Václav ; Šanda, František ; Lokstein, Heiko ; Hauer, Jürgen
Erschienen in
Photosynthesis Research, 2018, Jg. 135, H. 1-3, S. 45-54
ErschienenSpringer Netherlands, 2018
DokumenttypAufsatz in einer Zeitschrift
Schlagwörter (EN)LH2 / Ultrafast spectroscopy / Excitation energy transfer / Excitons / Photosynthesis
Projekt-/ReportnummerCzech-Austrian Mobility MSMT Grant: 7AMB16AT023 ; OeAD WTZ-project: CZ 09/2016 ; Czech Grant Agency: GA14-25752S ; European Research Council Advanced Grant STRATUS: ERC-2011-AdG No. 291198 ; Laserlab-Europe: EU-H2020 654148 ; Grant Agency of the Czech Republic GACR: #P501/12/G055
URNurn:nbn:at:at-ubtuw:3-4261 Persistent Identifier (URN)
 Das Werk ist frei verfügbar
Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum [3.03 mb]Supplementary material [0.97 mb]
Zusammenfassung (Englisch)

The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structurefunction relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed. Such transfer times are hard to accommodate by Förster theory, as the moderate coupling strengths found in LH2 suggest much slower transfer within this framework. In this study, we investigate LH2 from Phaeospirillum (Ph.) molischianum in two types of transient absorption experimentswith narrowband pump and white-light probe resulting in 100 fs time resolution, and with degenerate broadband 10 fs pump and probe pulses. With regard to the split Qx band in this system, we show that vibronically mediated transfer explains both the ultrafast carotenoid-to-B850 transfer, and the almost complete lack of transfer to B800. These results are beyond Förster theory, which predicts an almost equal partition between the two channels.

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