One- and two-color photon echo peak shift studies of photosystem I.

Department of Chemistry, University of California at Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
The Journal of Physical Chemistry B (Impact Factor: 3.38). 01/2007; 110(51):26303-12. DOI: 10.1021/jp061008j
Source: PubMed

ABSTRACT Wavelength-dependent one- and two-color photon echo peak shift spectroscopy was performed on the chlorophyll Qy band of trimeric photosystem I from Thermosynechococcus elongatus. Sub-100 fs energy transfer steps were observed in addition to longer time scales previously measured by others. In the main PSI absorption peak (675-700 nm), the peak shift decays more slowly with increasing wavelength, implying that energy transfer between pigments of similar excitation energy is slower for pigments with lower site energies. In the far-red region (715 nm), the decay of the peak shift is more rapid and is complete by 1 ps, a consequence of the strong electron-phonon coupling present in this spectral region. Two-color photon echo peak shift data show strong excitonic coupling between pigments absorbing at 675 nm and those absorbing at 700 nm. The one- and two-color peak shifts were simulated using the previously developed energy transfer model (J. Phys. Chem. B 2002, 106, 10251; Biophysical Journal 2003, 85, 140). The simulations agree well with the experimental data. Two-color photon echo peak shift is shown to be far more sensitive to variations in the molecular Hamiltonian than one-color photon echo peak shift spectroscopy.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two-dimensional electronic spectroscopy (2DES) was used to investigate the ultrafast energy-transfer dynamics of trimeric photosystem I of the cyanobacterium Thermosynechococcus elongatus. We demonstrate the ability of 2DES to resolve dynamics in a large pigment–protein complex containing 300 chromophores with both high frequency and time resolution. Monitoring the waiting-time-dependent changes of the line shape of the inhomogeneously broadened Qy(0–0) transition, we directly observe downhill energy equilibration on the 50 fs time scale.
    Journal of Physical Chemistry Letters 11/2012; 3(24):3677–3684. · 6.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three-pulse photon echo (3PPE) experiment has been applied to liquids, amorphous, and biological systems to elucidate the origin of the spectral line-broadening mechanism of optical transitions. 3PPE is a third-order nonlinear coherent optical process which is a part of the degenerate four-wave-mixing (DFWM) technique. Originally it was developed to determine electronic dephasing time in low-temperature glass and/or amorphous systems and simultaneously applied to solvation dynamics and/or spectral diffusion in condensed phase. Moreover, when a sufficiently short femtosecond laser pulse is utilized, it could also induce and control intramolecular coherent nuclear wavepacket motions. In the present review, we introduce the development and application of 3PPE spectroscopy in condensed phase, together with its basic background.
    Journal of Photochemistry and Photobiology C Photochemistry Reviews 03/2011; 12(1):31-45. · 11.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Transient grating (TG) signals in β-carotene homologues, by using sub-20-fs excitation pulses, were measured in order to investigate the dependence of the vibrational coherence dynamics on the π-conjugation length of these carotenoids. The experimental TG traces can be well reproduced by computational simulations based on a Brownian oscillator model using the spectral density determined from their respective resonance Raman spectra and their previously reported excited-state population-relaxation times. The total dephasing times of the ground-state vibrational modes of the homologues were determined by applying a wavelet transformation of their coherent oscillations, which were observed in the experimental TG traces. The total dephasing time decreases as the number of conjugated C=C double bonds increases. The decoherence of the ground-state vibrational modes in the homologues is mainly caused by system-bath interactions. The dephasing time of the C–C stretching modes strongly depends on the conjugation length, whereas that of the C=C stretching does not. This trend clearly shows that shorter-chain carotenoids have a specific major channel of energy dissipation to the environment (the C=C stretching), whereas the longer-chain carotenoids do not.
    Physical Review B 05/2008; 77(20). · 3.66 Impact Factor