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

Journal Article · Sun Jul 21 00:00:00 EDT 2013 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4813526· OSTI ID:22121678

Kosumi, Daisuke ^[1]; Nakagawa, Katsunori; Sakai, Shunsuke ^[2]; Nagaoka, Yuya; Maruta, Satoshi; Sugisaki, Mitsuru ^[3]; Dewa, Takehisa ^[2]; Nango, Mamoru ^[4]; Hashimoto, Hideki ^[4]

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1. Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)
2. Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)
3. CREST/JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
4. The Osaka City University Advanced Research Institute for Natural Science and Technology, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

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.

• OSTI ID: 22121678
• Journal Information: Journal of Chemical Physics, Vol. 139, Issue 3; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

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