Coherent nuclear dynamics at room temperature in bacterial reaction centers.
A room-temperature study is reported of the femtosecond spectral evolution of the stimulated emission band of the primary electron-transfer precursor P* in bacterial photosynthesis. The study was performed with membranes of the antenna-deficient RCO1 mutant of Rhodobacter sphaeroides. A time-dependent red shift, reflecting nuclear motion out of the Franck-Condon region of the excited state, is resolved. Analysis of oscillatory features persisting for > 1 ps in the kinetics revealed main frequencies of the activated motions at 30, 84, 145, and 192 cm-1. The oscillations occur on the time scale of primary electron transfer. Our results set a lower limit for the vibrational dephasing time in P* that is not compatible with the usual assumption in theoretical treatments of complete vibrational relaxation prior to electron transfer, even at room temperature.
Vos
M H
MH
Laboratoire d'Optique Appliquée, Ecole Polytechnique-Ecole Nationale Supérieure de Techniques Avancées, Palaiseau, France.
Jones
M R
MR
Hunter
C N
CN
Breton
J
J
Martin
J L
JL
D001429:Bacteriochlorophylls / Q000737:chemistry*; D055592:Biophysical Phenomena; D001703:Biophysics; D004579:Electron Transport; D007700:Kinetics; D009038:Motion; D010788:Photosynthesis; D012242:Rhodobacter sphaeroides; D013057:Spectrum Analysis; D013696:Temperature
D001429:Bacteriochlorophylls