Femtosecond spectral evolution of the excited state of bacterial reaction centers at 10K
- Ecole Polytechnique-Ecole Nationale Superieure de Techniques Avancees, Palaiseau (France) Centre de'Etudes Nucleaires de Saclay, Gif-sur-Yvette (France)
- Ecole Polytechnique-Ecole Nationale Superieure de Techniques Avancees, Palaiseau (France)
- Massachusetts Inst. of Tech., Cambridge (United States); Centre d'Etudes Nucleaires de Saclay (France)
The femtosecond spectral evolution of reaction centers of Rhodobacter sphaeroides R-26 was studied at 10 K. Transient spectra in the near infrared region, obtained with 45-fs pulses were analyzed with associated kinetics at specific wavelengths. A complex spectral evolution in the 800-nm region, most notably the bleaching of the 796-nm band, takes place within a few hundred femtosecond-i.e., on a time scale much faster than electron transfer from the primary donor P to the bacteriopheophytin acceptor H{sub L}. The remarkable initial spectral features and their evolution are presumably related to the presence of H{sub L}, as they were not observed in the D{sub LL} mutant of Rhodobacter capsulatus, which lacks this pigment. A simple linear reaction scheme with an intermediate state cannot account for the authors data; the initial spectral evolution must reflect relaxation processes within the excited state. The importance for primary photochemistry of long distance interactions in the reaction center is discussed.
- DOE Contract Number:
- FG02-90ER20019
- OSTI ID:
- 5597098
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 89:2; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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