Exciton relaxation and polaron formation in LH2 at low temperature

被引：64

作者：

Polivka, T ^{[1
]}

Pullerits, T ^{[1
]}

Herek, JL ^{[1
]}

Sundström, V ^{[1
]}

机构：

[1] Univ Lund, S-22100 Lund, Sweden

来源：

JOURNAL OF PHYSICAL CHEMISTRY B | 2000年 / 104卷 / 05期

关键词：

D O I：

10.1021/jp9915984

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Excited state dynamics of antenna complexes in an LH2-only mutant of the purple bacterium Rb, sphaeroides have been investigated by means of two-color femtosecond spectroscopy combined with computer simulations. Measurements of transient absorption spectra revealed a new spectral band in the stimulated emission region around 880 nm at 6 K. To simulate this new dynamic feature that appears within the first 2 ps after light absorption. we have used a simplified polaron model via a decoupled red pigment within the B850 ring. Comparison of simulations and experiment suggests the following kinetic scheme: (1) initial ultrafast (similar to 100 fs) dynamics correspond to exciton relaxation to the lowest exciton state; (2) mixing of the lowest exciton state with charge-transfer states results in a relaxation to these states in about 600 fs; (3) picosecond dielectric relaxation in the charge-transfer states corresponding to polaron formation follows.

引用

页码：1088 / 1096

页数：9

共 42 条

[1] Calculations of spectroscopic properties of the LH2 bacteriochlorophyll - Protein antenna complex from Rhodopseudomonas acidophila [J].