Nature of Disorder and Inter-Complex Energy Transfer in LH2 at Room Temperature:  A Three Pulse Photon Echo Peak Shift Study

Agarwal, Ritesh; Rizvi, Abbas H.; Prall, Bradley S.; Olsen, John D.; Hunter, C. Neil; Fleming, Graham R.

doi:10.1021/jp014054m

Cited by 57 publications

(57 citation statements)

References 53 publications

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“…8 and 16. Our minimal model is constructed by using structural information about all 27 BChls of LH3 (17) and data from previous experiments and simulations on the LH2 complex (14,(24)(25)(26)(27)(28). Each BChl (a site in the model complex) is represented by a two-level system describing its S 0 3 S 1 transition (the Q y transition of the BChl) to which we assign a site energy, E n , and an electronic transition dipole moment, d n .…”

Section: Theoretical Modeling and Discussionmentioning

confidence: 99%

“…26. Additional external disorder parameters ⌺ B800 and ⌺ B820 that might play a significant role for the complexes embedded in mem-branes (24,26) are assumed to be zero for the complexes in solution. For the sake of simplicity we neglect effects of the coupling disorder in current treatment, although to achieve a higher level of agreement with the experimental data this effect has to be included (29).…”

Section: Theoretical Modeling and Discussionmentioning

confidence: 99%

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Two-dimensional electronic spectroscopy of the B800–B820 light-harvesting complex

Zigmantas

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Mančal

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Emerging nonlinear optical spectroscopies enable deeper insight into the intricate world of interactions and dynamics of complex molecular systems. 2D electronic spectroscopy appears to be especially well suited for studying multichromophoric complexes such as light-harvesting complexes of photosynthetic organisms as it allows direct observation of couplings between the pigments and charts dynamics of energy flow on a 2D frequency map. Here, we demonstrate that a single 2D experiment combined with self-consistent theoretical modeling can determine spectroscopic parameters dictating excitation energy dynamics in the bacterial B800-B820 light-harvesting complex, which contains 27 bacteriochlorophyll molecules. Ultrafast sub-50-fs dynamics dominated by coherent intraband processes and population transfer dynamics on a picosecond time scale were measured and modeled with one consistent set of parameters. Theoretical 2D spectra were calculated by using a Frenkel exciton model and modified Fö rster͞ Redfield theory for the calculation of dynamics. They match the main features of experimental spectra at all population times well, implying that the energy level structure and transition dipole strengths are modeled correctly in addition to the energy transfer dynamics of the system. photosynthetic complexes ͉ excitons ͉ multichromophoric systems ͉ ultrafast spectroscopy T wo-dimensional optical experiments constitute a promising addition to the field of ultrafast spectroscopy. The success of 2D IR spectroscopy in adapting techniques from multidimensional NMR is steadily expanding into the visible range, where coherent couplings between electronic transitions, frequencydependent excitation transfer processes, and chromophoreenvironment interactions in complex molecular systems can be investigated with femtosecond time resolution. As demonstrated first by Jonas and coworkers (1-3) for visible-range laser excitation pulses, Fourier analysis of the signal electric field in a phase-controlled, four-wave mixing experiment yields 2D frequency maps representing the full (within the laser pulse spectral window) third-order optical response of the system. 2D electronic experiments performed thus far are based on heterodyne detection of a three-pulse photon echo signal, which is separated from other nonlinear signals by phase matching in a noncollinear beam geometry (1, 2, 4-6), or fluorescence detection after phase cycling using pulse-shaping techniques, as performed by Tian et al. (7). Brixner et al. (4,5) developed a particularly robust experimental setup combining inherent phase stability, phase matching, and heterodyne detection by spectral interferometry, and they later demonstrated that the method was well suited to the study of multichromophoric pigment-protein complexes (8).Multiple third-order nonlinear signals interfere to give the overall three-pulse photon echo signal, and thus quantitative analysis is essential for disentangling contributions to 2D spectra and identifying the source of spectral features. Simulation o...

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Section: Theoretical Modeling and Discussionmentioning

confidence: 99%

Section: Theoretical Modeling and Discussionmentioning

confidence: 99%

Two-dimensional electronic spectroscopy of the B800–B820 light-harvesting complex

Zigmantas

Read

Mančal

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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204

193

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“…To simulate external disorder as defined in refs. [24,63], the result can be convoluted with another inhomogeneous distribution function (also modeled by a Gaussian distribution) with a standard deviation of s ext . As seen below, we allow s ext to be different for absorbing and emitting states.…”

Section: Absorbing Frenkel Exciton Statesmentioning

confidence: 99%

Davydov Splitting of Excitons in Cyclic Bacteriochlorophyll a Nanoaggregates of Bacterial Light‐Harvesting Complexes between 4.5 and 263 K

et al. 2011

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The nature of electronic excitations created by photon absorption in the cyclic B850 aggregates of 18 bacteriochlorophyll molecules of LH2 antenna complexes of photosynthetic bacteria is studied over a broad temperature range using absorption, fluorescence, and fluorescence anisotropy spectra. The latter technique has been proved to be suitable for revealing the hidden structure of excitons in inhomogeneously broadened spectra of cyclic aggregates. A theoretical model that accounts for differences of absorbing excitons in undeformed and emitting exciton polarons in deformed antenna lattices is also developed. Only a slight decrease of the exciton bandwidth and exciton coupling energy with temperature is observed. Survival of excitons in the whole temperature span from cryogenic to nearly ambient temperatures strongly suggests that collective, coherent electronic excitations might play a role in the functional light-harvesting process taking place at physiological temperatures.

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“…However, in discussing the energy dissipation, the four-wave mixing (FWM) is a more sophisticated method because one can directly observe the phase relaxation during the measurement. The relationship between the energy transfer and energy dissipation has been discussed in LH2 (Joo et al 1996;Yang et al 2001;Agarwal et al 2002;Hornung et al 2005). However, we do not have enough knowledge on the decoherence in carotenoids.…”

Section: Introductionmentioning

confidence: 99%

Four-wave mixing signals from β-carotene and its n = 15 homologue

et al. 2007

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The third-order nonlinear optical responses of beta-carotene and its homologue having a conjugation-double bond n = 15 have been investigated using sub-20 fs ultra-short optical pulses in order to clarify the dissipation processes of excess energy. Using the four-wave mixing spectroscopy, we observed a clear coherent oscillation with a period of a few tens of femtoseconds. The spectral density of these molecules was estimated that allowed the theoretical linear and nonlinear optical signals to be directly compared with the experimental data. Calculations based on the Brownian oscillator model were performed under the impulsive excitation limit. We show that the memory of the vibronic coherence generated upon the excitation into the S(2) state is lost via the relaxation process including the S(1) state. The vibronic decoherence lifetime of the system was estimated to be 1 ps, which is about 5 times larger than the life time of the S(2) state ( approximately 150 fs) determined in previous studies. The role of coherence and the efficient energy transfer in the light-harvesting antenna complexes are discussed.

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Nature of Disorder and Inter-Complex Energy Transfer in LH2 at Room Temperature: A Three Pulse Photon Echo Peak Shift Study

Cited by 57 publications

References 53 publications

Two-dimensional electronic spectroscopy of the B800–B820 light-harvesting complex

Two-dimensional electronic spectroscopy of the B800–B820 light-harvesting complex

Davydov Splitting of Excitons in Cyclic Bacteriochlorophyll a Nanoaggregates of Bacterial Light‐Harvesting Complexes between 4.5 and 263 K

Four-wave mixing signals from β-carotene and its n = 15 homologue

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