Polarized pump-probe spectroscopy of photosystem I antenna excitation transport

Journal Article · Thu Sep 07 00:00:00 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), Vol. 93:18; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

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