An ultrafast time‐resolved anisotropy study of bacteriochlorophyll a in pyridine

FEBS Letters

Åkesson, Eva¹  Sundström, Villy¹  Martinsson, Peter¹ 

[1] Department of Chemical Physics, Lund University, P.O. Box 124, S-22100 Lund, Sweden

关键词: Bacteriochlorophyll a;    Transient absorption anisotropy;    Excited state absorption;   

DOI  :  10.1016/S0014-5793(99)01725-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The transient absorption anisotropy spectrum of bacteriochlorophyll a (BChl a) in pyridine was measured in the wavelength interval 550–850 nm, 1 ps after optical excitation with a 792-nm femtosecond light pulse. In the wavelength region of Q _y absorption and stimulated emission (775–825 nm), the anisotropy was found to be close to the theoretically expected value (0.4) for a two-level system. In the wavelength region 650–750 nm, where the transient absorption signal is dominated by excited state absorption, the anisotropy is reduced to ∼0.18. Anisotropy kinetics were measured at several wavelengths and found to be constant within the time window 0–5 ps, showing that no internal dynamics of the BChl a molecule change the anisotropy on the time scale of tens of picoseconds.

【 授权许可】

Unknown