Paper
30 May 2002 Collective librations in the LH2 antenna systems and modulated broadening of B800 and B850 absorption spectra
Vladimir S. Pavlovich
Author Affiliations +
Abstract
The collective librations of the linked polar fragments and polar elements in the LH2 antenna complex and in the protein environment of the photosynthetic purple bacteria are described as a motion of the histons, new quasi-particles. Assuming that the exciton-phonon coupling is fairly weak, we study the effect of the dynamic disorder on the B800 and B850 absorption spectra as a result of the exciton-histon interactions. Taking into account that the histons modulate the frequency of exciton transitions, the mean-square thermal fluctuation of the frequency and the half-width of absorption spectra have been defined as a function of the difference in permanent dipole moment between excited and ground states. Theory is used for interpretation of the well-known experimental data on thermal broadening of the B800 for LH2 of Rb. Sphaeroides and Rps. Acidophila in the glycerol-water solvent. In the calculations it is suggested that the effects of static disorder are enchanged under these temperature conditions. Obtained equation for the full half-width provides an excellent fit to the Rb. Sphaeroides and Rps. Acidophila B800 known data at 4.2-270 K with an average histon frequency of 63 and 50 cm-1, respectively. The reasons of large distinction of the zero- phonon hole half-widths at the laser burn wavelengths near the B800 and B850 maxima are also briefly discussed.
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Vladimir S. Pavlovich "Collective librations in the LH2 antenna systems and modulated broadening of B800 and B850 absorption spectra", Proc. SPIE 4749, ICONO 2001: Novel Trends in Nonlinear Laser Spectroscopy and Optical Diagnostics and Lasers in Chemistry, Biophysics, and Biomedicine, (30 May 2002); https://doi.org/10.1117/12.468923
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KEYWORDS
Modulation

Absorption

Antennas

Rubidium

Proteins

Excitons

Molecules

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