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Title: B896 and B870 components of the rhodobacter sphaeroides antenna: A hole burning study

Abstract

Novel nonphotochemical hole burning action spectra are presented that yield the low-temperature absorption profiles of B896 and B870 and their underlying structures (linear electron-phonon coupling and site inhomogeneous broadening). The results establish that B896 and B870 are associated with the far more intense B875 and B850 bacteriochlorophyll {alpha} absorption bands, respectively, of the light harvesting I and II complexes. The homogeneous widths of the B896 and B870 zero-phonon holes are the same within experimental uncertainty, 3.2 cm{sup {minus}1} at 4.2 K, which corresponds to a total optical dephasing time of 6.6 ps. A number of interpretations for B870 and B896 are considered. Favored is one in which they are due to the lowest energy levels of the B850* and B875* exciton bands (asterisk denoting the S{sub 1}(Q{sub y}) state). Based on studies of the dephasing of excitons in organic crystals, the 6.6-ps dephasing of B896* is attributed to exciton scattering with energetic inequivalent neighboring unit cells. Such scattering and B870 to B875 energy transfer are suggested to be contributors to the dephasing of B870*. The effect of glasslike structural heterogeneity on the optical selection rules for unit cells of cyclic symmetry is also considered. 71 refs., 5 figs.

Authors:
;  [1];  [2]
  1. Iowa State Univ., Ames, IA (United States)
  2. E.E. Aula Dei, CSIC, Zaragoza (Spain)
Publication Date:
OSTI Identifier:
554929
DOE Contract Number:  
W-7405-ENG-82
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry
Additional Journal Information:
Journal Volume: 96; Journal Issue: 15; Other Information: PBD: 23 Jul 1992
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; CHLOROPHYLL-BINDING PROTEINS; ELECTRON-PHONON COUPLING; ENERGY TRANSFER; COMPLEXES; PHOTOSYNTHESIS

Citation Formats

Reddy, N R.S., Small, G J, and Picorel, R. B896 and B870 components of the rhodobacter sphaeroides antenna: A hole burning study. United States: N. p., 1992. Web. doi:10.1021/j100194a065.
Reddy, N R.S., Small, G J, & Picorel, R. B896 and B870 components of the rhodobacter sphaeroides antenna: A hole burning study. United States. doi:10.1021/j100194a065.
Reddy, N R.S., Small, G J, and Picorel, R. Thu . "B896 and B870 components of the rhodobacter sphaeroides antenna: A hole burning study". United States. doi:10.1021/j100194a065.
@article{osti_554929,
title = {B896 and B870 components of the rhodobacter sphaeroides antenna: A hole burning study},
author = {Reddy, N R.S. and Small, G J and Picorel, R},
abstractNote = {Novel nonphotochemical hole burning action spectra are presented that yield the low-temperature absorption profiles of B896 and B870 and their underlying structures (linear electron-phonon coupling and site inhomogeneous broadening). The results establish that B896 and B870 are associated with the far more intense B875 and B850 bacteriochlorophyll {alpha} absorption bands, respectively, of the light harvesting I and II complexes. The homogeneous widths of the B896 and B870 zero-phonon holes are the same within experimental uncertainty, 3.2 cm{sup {minus}1} at 4.2 K, which corresponds to a total optical dephasing time of 6.6 ps. A number of interpretations for B870 and B896 are considered. Favored is one in which they are due to the lowest energy levels of the B850* and B875* exciton bands (asterisk denoting the S{sub 1}(Q{sub y}) state). Based on studies of the dephasing of excitons in organic crystals, the 6.6-ps dephasing of B896* is attributed to exciton scattering with energetic inequivalent neighboring unit cells. Such scattering and B870 to B875 energy transfer are suggested to be contributors to the dephasing of B870*. The effect of glasslike structural heterogeneity on the optical selection rules for unit cells of cyclic symmetry is also considered. 71 refs., 5 figs.},
doi = {10.1021/j100194a065},
journal = {Journal of Physical Chemistry},
number = 15,
volume = 96,
place = {United States},
year = {1992},
month = {7}
}