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Title: Ultrafast intramolecular relaxation dynamics of Mg- and Zn-bacteriochlorophyll a

Ultrafast excited-state dynamics of the photosynthetic pigment (Mg-)bacteriochlorophyll a and its Zn-substituted form were investigated by steady-state absorption/fluorescence and femtosecond pump-probe spectroscopic measurements. The obtained steady-state absorption and fluorescence spectra of bacteriochlorophyll a in solution showed that the central metal compound significantly affects the energy of the Q{sub x} state, but has almost no effect on the Q{sub y} state. Photo-induced absorption spectra were recorded upon excitation of Mg- and Zn-bacteriochlorophyll a into either their Q{sub x} or Q{sub y} state. By comparing the kinetic traces of transient absorption, ground-state beaching, and stimulated emission after excitation to the Q{sub x} or Q{sub y} state, we showed that the Q{sub x} state was substantially incorporated in the ultrafast excited-state dynamics of bacteriochlorophyll a. Based on these observations, the lifetime of the Q{sub x} state was determined to be 50 and 70 fs for Mg- and Zn-bacteriochlorophyll a, respectively, indicating that the lifetime was influenced by the central metal atom due to the change of the energy gap between the Q{sub x} and Q{sub y} states.
Authors:
 [1] ;  [2] ; ;  [3] ; ; ;  [4] ;  [2] ;  [3] ;  [2] ;  [5] ;  [2] ;  [2] ;  [5] ;  [2] ;  [2]
  1. Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)
  2. (Japan)
  3. Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)
  4. CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
  5. The Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)
Publication Date:
OSTI Identifier:
22121678
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 3; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 60 APPLIED LIFE SCIENCES; ABSORPTION; ABSORPTION SPECTRA; BIOPHYSICS; CHLOROPHYLL; ENERGY GAP; EXCITATION; EXCITED STATES; FLUORESCENCE; FLUORESCENCE SPECTROSCOPY; GROUND STATES; LIFETIME; MAGNESIUM COMPLEXES; MICROORGANISMS; PHOTOSYNTHESIS; RELAXATION; STEADY-STATE CONDITIONS; STIMULATED EMISSION; ZINC COMPLEXES