High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum

doi:https://doi.org/10.1021/j100043a070

Title: High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum

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Abstract

The dependence of the low-temperature Q{sub y} absorption and nonphotochemical hole-burned spectra of the title complex (also known as the FMO complex) on pressure (<= 700 MPa) is reported. Pressure-induced structural changes of the complex were found to be elastic. The linear pressure shifts at 4.2 K for the principal absorption bands at 805, 814 and 825 nm are -0.08, -0.11, and -0.11 cm{sup -1}/MPa, respectively. Importantly, the 825 and 814 nm absorption profiles (shape, intensity) are independent of pressure. The results establish that, even at the highest values used, pressure has only a weak effect on the pairwise excitonic couplings of the bacteriochlorophyll (BChl) molecules, inhomogeneous broadening, and electron-phonon coupling. The pressure dependence of the Q{sub y} spectrum and zero-phonon holes (ZPH) burned in the 825 nm band can be rationalized in terms of dispersion interactions when BChl occupation numbers for the exciton levels are taken into account. These ZPH, which are assigned to the lowest level at 827 nm, carry a width of 0.6 cm{sup -1} at 4.2 K, which is independent of the pressure at which the hole is burned. This width is ascribed to dephasing, T{sub 2} = 35 ps. Possible mechanisms for the dephasing aremore »« less

Authors:

Reddy, N R.S.; Jankowiak, R; Small, G J ^[1]

Ames Lab., IA (United States)

Publication Date:: 1995-10-26

Sponsoring Org.:: USDOE

OSTI Identifier:: 159719

DOE Contract Number:: W-7405-ENG-82

Resource Type:: Journal Article

Journal Name:: Journal of Physical Chemistry

Additional Journal Information:: Journal Volume: 99; Journal Issue: 43; Other Information: PBD: 26 Oct 1995

Country of Publication:: United States

Language:: English

Subject:: 40 CHEMISTRY; 55 BIOLOGY AND MEDICINE, BASIC STUDIES; CHLOROPHYLL; ABSORPTION SPECTRA; COMPLEXES; PHOTOCHEMICAL REACTIONS; ELECTRON-PHONON COUPLING; PRESSURE DEPENDENCE; ENERGY LEVELS; PHOTOSYNTHETIC BACTERIA

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                    Reddy, N R.S., Jankowiak, R, Small, G J, and Iowa State Univ., Ames, IA. High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum.  United States: N. p., 1995. 
        Web.  doi:10.1021/j100043a070.

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                    Reddy, N R.S., Jankowiak, R, Small, G J, & Iowa State Univ., Ames, IA. High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum.  United States.  https://doi.org/10.1021/j100043a070

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                    Reddy, N R.S., Jankowiak, R, Small, G J, and Iowa State Univ., Ames, IA. Thu .  
        "High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum".  United States.  https://doi.org/10.1021/j100043a070.

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@article{osti_159719,

  title        = {High-pressure hole-burning studies of the bacteriochlorophyll a antenna complex from Chlorobium tepidum},

  author       = {Reddy, N R.S. and Jankowiak, R and Small, G J and Iowa State Univ., Ames, IA},

  abstractNote = {The dependence of the low-temperature Q{sub y} absorption and nonphotochemical hole-burned spectra of the title complex (also known as the FMO complex) on pressure (<= 700 MPa) is reported. Pressure-induced structural changes of the complex were found to be elastic. The linear pressure shifts at 4.2 K for the principal absorption bands at 805, 814 and 825 nm are -0.08, -0.11, and -0.11 cm{sup -1}/MPa, respectively. Importantly, the 825 and 814 nm absorption profiles (shape, intensity) are independent of pressure. The results establish that, even at the highest values used, pressure has only a weak effect on the pairwise excitonic couplings of the bacteriochlorophyll (BChl) molecules, inhomogeneous broadening, and electron-phonon coupling. The pressure dependence of the Q{sub y} spectrum and zero-phonon holes (ZPH) burned in the 825 nm band can be rationalized in terms of dispersion interactions when BChl occupation numbers for the exciton levels are taken into account. These ZPH, which are assigned to the lowest level at 827 nm, carry a width of 0.6 cm{sup -1} at 4.2 K, which is independent of the pressure at which the hole is burned. This width is ascribed to dephasing, T{sub 2} = 35 ps. Possible mechanisms for the dephasing are considered, and its pressure independence is discussed. 80 refs., 12 figs., 1 tab.},

  doi          = {10.1021/j100043a070},

  url          = {https://www.osti.gov/biblio/159719},
  journal      = {Journal of Physical Chemistry},
number       = 43,

  volume       = 99,

  place        = {United States},

  year         = {1995},

  month        = {10}

}

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