Femtosecond spectroscopy and vibrational coherence of membrane-bound RCs of Rhodobacter sphaeroides genetically modified at Positions M210 and L181
The mechanism of primary charge separation in bacterial reaction centers is still subject to debate . Amongst other questions, the functional role of coherent motions from non-thermalized vibrational states has to be evaluated. The potential energy surface of the excited donor state P* is strongly displaced with respect to the ground state for a number of low-frequency vibrational modes. This has been extensively documented by photochemical holeburning [2, 3, 4] and resonance Raman [5,6] studies. Using femtosecond spectroscopy to monitor oscillations in the stimulated emission band shape, we have previously shown that phase correlations for those modes are maintained on the timescale of electron transfer [7,8]. In the usual assumption that vibrational dephasing precedes or at most is concomitant with the processes of energy exchange, these observations imply that the entire vibrational manifold of P* is not thermalized on the timescale of ET.
KeywordsPotential Energy Surface Transient Absorption Spectrum Ground State Absorption Primary Charge Separation Bacterial Reaction Center
Unable to display preview. Download preview PDF.
- 1.The Photosynthetic Reaction Center, Deisenhofer, J. & Norris, J.R., eds. Academic Press, New York, 1993.Google Scholar