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Proceedings Paper

Collective librations in the LH2 antenna systems and modulated broadening of B800 and B850 absorption spectra
Author(s): Vladimir S. Pavlovich
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Paper 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.

Paper Details

Date Published: 30 May 2002
PDF: 5 pages
Proc. SPIE 4749, ICONO 2001: Novel Trends in Nonlinear Laser Spectroscopy and Optical Diagnostics and Lasers in Chemistry, Biophysics, and Biomedicine, (30 May 2002); doi: 10.1117/12.468923
Show Author Affiliations
Vladimir S. Pavlovich, Institute of Molecular and Atomic Physics (Belarus)


Published in SPIE Proceedings Vol. 4749:
ICONO 2001: Novel Trends in Nonlinear Laser Spectroscopy and Optical Diagnostics and Lasers in Chemistry, Biophysics, and Biomedicine

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