Ultrafast studies of exciton dynamics in light harvesting dimers

被引：3

作者：

Arnett, DC ^{[1
]}

Kumble, R ^{[1
]}

Visschers, RW ^{[1
]}

Moser, CC ^{[1
]}

Dutton, PL ^{[1
]}

Hochstrasser, RM ^{[1
]}

Scherer, NF ^{[1
]}

机构：

[1] Pacific NW Labs, Environm Mol Sci Lab, Richland, WA 99353 USA

来源：

LASER TECHNIQUES FOR CONDENSED-PHASE AND BIOLOGICAL SYSTEMS | 1998年 / 3273卷

关键词：

photosynthesis; femtosecond; anisotropy; exciton; B820; photosynthetic reaction center; Rs rubrum; Rb sphaeroides;

D O I：

10.1117/12.306115

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

The electronic characteristics and rapid dynamics associated with bacteriochlorophyll dimers in photosynthetic systems are investigated using novel ultrafast anisotropy techniques. The excitonic structure of isolated dimeric subunits (B820) from the core (LH-1) light harvesting complex of Rs. Rubrum and the reassociated complex (B873) is revealed in coherent anisotropy responses following impulsive excitation. For B820, the oscillatory anisotropy responses indicate excitonic splitting frequencies ranging from 370 cm(-1) to 490 cm(-1) indicating significant inhomogeneity in the excitonic spectrum. The complete set of wavelength dependent anisotropy results is analyzed to reveal the sources of inhomogeneity for B820; correlated distributions of dimer energetic parameters are necessary to reproduce the results. The coherent responses of reassociated B873 complexes exhibit multiple frequencies, revealing the extended excitonic structure of the aggregates. In other experiments, the electronic properties of the photosynthetic reaction center and the rapid electronic dynamics prior to charge separation are investigated by both "two color" anisotropy and coherent anisotropy. A variety of excitation and detection conditions provide the first room temperature characterization of the excitonic structure of the special pair, and a detailed description of rapid energy transfer to and within the special pair. The results presented here stress the importance of delocalized excitation in both the light harvesting antenna complexes and the photosynthetic reaction center.

引用

页码：244 / 255

页数：12