Primary photochemical processes in P700-enriched photosystem I particles: Trap-limited excitation decay and primary charge separation

Journal Article · Thu Oct 06 00:00:00 EDT 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100091a057· OSTI ID:6842177

Kumazaki, Shigeichi; Kandori, Hideki; Petek, Hrvoje; Yoshihara, Keitaro ^[1]; Ikegami, Isamu ^[2]

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1. Inst. for Molecular Science, Okazaki (Japan)
2. Teikyo Univ., Kanagawa (Japan)

The energy transfer and primary charge separation in photosystem I (PS I) reaction center (RC) particles with an antenna size of 12 chlorophyll/P700 were studied by subpicosecond transient absorption spectroscopy. Upon excitation of the particles at 638 nm under the donor chlorophyll (P700)-neutral conditions, the transition from the excited state of chlorophylls to the charge-separated state of P700[sup +]A[sub 0][sup [minus]] (A[sub 0]; acceptor chlorophyll [alpha]) proceeded with a time constant of 6.5 ps at [approximately]278 K. This time constant was obtained from the absorption increase of P700[sup +]A[sub 0][sup [minus]] at 740 ([+-]10) nm, where excited chlorophylls gave only a negligible absorbance change. The distribution of electronic excitation energy among different chlorophyll forms, which was monitored in the wavelength region 650-720 nm, did not show and significant change from 500 fs to 12 ps under both the P700-preoxidized and -neutral conditions. Comparison of the experimental distribution with simulated ones suggests that the excitation energy is distributed within 500 fs highly on P700 and also among other higher-energy chlorophyll forms. 55 refs., 9 figs.

• OSTI ID: 6842177
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 98:40; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHLOROPHYLL
ENERGY TRANSFER
EXCITED STATES
ABSORPTION SPECTROSCOPY
BOLTZMANN STATISTICS
ELECTRON TRANSFER
PHOTOSYNTHETIC REACTION CENTERS
SPINACH
CARBOXYLIC ACIDS
ENERGY LEVELS
FOOD
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
SPECTROSCOPY
VEGETABLES
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400102 - Chemical & Spectral Procedures
400500 - Photochemistry