Femtosecond and hole-burning studies of B800`s excitation energy relaxation dynamics in the LH2 antenna complex of Rhodopseudomonas acidophila (strain 10050)

Journal Article · Thu Jul 18 04:00:00 EDT 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp9608178· OSTI ID:380818

Wu, H M; Savikhin, S; Reddy, N R.S.; Jankowiak, R; Struve, W S; Small, G J ^[1]; Cogdell, R J ^[2]

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1. Ames Lab., IA (United States)
2. Univ. of Glasgow (United Kingdom)

One- and two-color pump/probe femtosecond and hole-burning data are reported for the isolated B800-850 (LH2) antenna complex of Rhodopseudomonas acidophila (strain 10050). The two-color profiles are interpretable in terms of essentially monophasic B800{yields}B850 energy transfer with kinetics ranging from 1.6 to 1.1 ps between 19 and 130 K for excitation at or to the red of the B800 absorption maximum. The B800 zero-phonon hole profiles obtained at 4.2 K with burn frequencies located near or to the red of this maximum yielded a transfer time of 1.8 ps. B800 hole-burning data (4.2 K) are also reported for chromatophores at ambient pressure and pressures of 270 and 375 MPa. At ambient pressure the B800-B850 energy gap is 950 cm{sup -1}, while at 270 and 375 MPa it is close to 1000 and 1050 cm{sup -1}, respectively. However, no dependence of the B800{yields}B850 transfer time on pressure was observed. The resilience of the transfer rate to pressure-induced changes in the energy gap and the weak temperature dependence of the rate are consistent with the model that has the spectral overlap (of Foerster theory) provided by the B800 fluorescence origin band and weak vibronic absorption bands of B850. However, both the time domain and hole-burning data establish that there is an additional relaxation channel for B800, which is observed when excitation is located to the blue of the B800 absorption maximum. 40 refs., 11 figs., 6 tabs.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 380818
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 29 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
40 CHEMISTRY
55 BIOLOGY AND MEDICINE
BASIC STUDIES
ABSORPTION SPECTRA
BACTERIA
CALCULATION METHODS
DYNAMICS
ENERGY TRANSFER
HOLES
ORGANIC COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
RELAXATION
SIMULATION
TEMPERATURE DEPENDENCE