Polarized pump-probe spectroscopy of photosystem I antenna excitation transport

Journal Article · Thu Sep 07 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100355a053· OSTI ID:7107937

Causgrove, T P; Yang, Shumei; Struve, W S ^[1]

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1. Iowa State Univ., Ames (USA)

Polarized photobleaching profiles were obtained by using pump-probe techniques with {approx} 1.5-ps resolution at 645-681 nm in solutions of native photosystem I particles (Chl/P700 {approx} 200) from spinach. The isotropic Chl a ground-state recovery dynamics at wavelengths between 660 and 681 nm exhibit at least three decay components; triexponential fits yield lifetimes of <5 ps, 25-40 ps, and 200-250 ps. The isotropic photobleaching decay is far more rapid at 645-655 nm, exhibiting {approx} 2 ps decay time at the shortest wavelength. Since this spectral region spans the Chl b Q{sub y} transition, the latter kinetics may arise from excitation migration from peripheral Chl b pigments to longer wavelength Chl a pigments. The depolarization lifetimes exhibited by Chl a anisotropic photobleaching profiles vary considerably with wavelength between 660 and 681 nm, in a manner which is consistent with Foerster excitation transport rates computed from photosystem I core antenna absorption spectra. While electronic excitation may be rapidly homogenized across the Chl a core antenna spectrum, the slow depolarization time scales (5-13 ps) show that such rapid homogenization does not extend spatially over the entire core antenna. The results are consistent with a core antenna model in which the various Chl a spectral forms are grouped into heterogeneous clusters of chromophores.

• OSTI ID: 7107937
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:18; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000 -- Chemistry
400500* -- Photochemistry
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANTENNAS
CHEMISTRY
DATA
DATA ANALYSIS
ELECTRICAL EQUIPMENT
ELECTRONIC STRUCTURE
EQUIPMENT
EXCITATION SYSTEMS
EXPERIMENTAL DATA
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
PHOTOCHEMISTRY
PLANT CELLS