Spectral dependence of polarization of the LH2 complex from photosynthetic purple bacterium Thiorhodospira sibirica under femtosecond excitation and probing within near IR spectral regionстатья
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Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Spectral dependence of photoinduced absorption changes in LH2 complex (B800-830-850) from Thiorhodospira sibirica was investigated under ultrafast light pulse excitation (similar to 50 fs, 800 nm) at room temperature. This complex has anomalous absorption spectrum with three peaks in near infrared spectral region at approximately 800, 830 and 850 nm. Negative polarization degree (-0.05...-0.1) was formed at long wavelength side of the spectrum (860-900 nm), which is an evidence of high value of the angle between transition moment directions of B800 and B850 band. It was shown that the absorption spectrum for LH2 complex from Trs. sibirica, calculated on the basis of the model proposed in [27] is determined by absorption spectrum of trimer formed by neighboring bacteriochlorophyll molecules. Long wavelength (13850) and short wavelength (B800) bands of trimer (and whole LH2 complex) may be interpreted as significantly spaced bands of strong interacting BChl molecules of the dimer BCh1800-13Ch1850 alpha. Intermediate B830 band is determined by superposition of slightly spaced bands of dimers BCh1800-BCh1850 beta and BCh1850 alpha-BCh1850 beta with weak interaction. It is concluded that the structure of complex LH2 from Trs. sibirica differs significantly from that of the same complexes from other purple bacteria.