Emitting Excitonic Polaron States in Core LH1 and Peripheral LH2 Bacterial Light-Harvesting Complexes

Timpmann, Kõu; Rätsep, Margus; Hunter, C. Neil; Freiberg, Arvi

doi:10.1021/jp049165a

Cited by 57 publications

(102 citation statements)

References 31 publications

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“…Moreover, we observed a clear correlation between the spectral peak position of the emission and the widths of the emission spectra. In agreement with selective spectroscopy data obtained from ensembles of LH2, [32,33] the complexes with emission spectra that featured a clear ZPL/PSB profile occurred preferentially on the blue side of the ensembleaveraged emission peak, and complexes with rather redshifted spectra typically featured structureless broad bands. This observation clearly indicates that the electron-phonon coupling strength strongly varies from complex to complex, as well as being a function of the spectral position.…”

supporting

confidence: 87%

Fluctuations in the Electron–Phonon Coupling of a Single Chromoprotein

Kunz¹,

Timpmann²,

Southall³

et al. 2013

Angewandte Chemie

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Sequenzen von hochaufgelösten Tieftemperaturemissionsspektren einzelner LH2‐Lichtsammelkomplexe von Rhodopseudomonas acidophila zeigen eine deutlich größere Vielfalt an Emissionsprofilen als zuvor beobachtet. Die Ergebnisse liefern einen direkten Beleg für beträchtliche Fluktuationen in der Elektron‐Phonon‐Kopplung und, verbunden damit, der Excitonen(de)lokalisierung innerhalb einzelner Pigment‐Protein‐Komplexe.

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supporting

confidence: 87%

Fluctuations in the Electron–Phonon Coupling of a Single Chromoprotein

Kunz¹,

Timpmann²,

Southall³

et al. 2013

Angewandte Chemie

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“…The idea of exciton polarons/self-trapped excitons in bacterial LH antennas has been around for at least a decade already. [23,34,49,50,52,53,66,67] Existence of similar quasi-localized excitations in DNA [68] as well as in photosynthetic reaction centers [13] has also been proposed recently. Successful reproduction of most subtle features of the measured spectra demonstrated above is another strong evidence for exciton polarons in the cyclic bacterial antennas.…”

Section: Discussionmentioning

confidence: 99%

“…Our model of phonon bath was verified by comparing with experimental low-temperature phonon sidebands of the line-narrowed fluorescence difference spectra. [52,53] Herein, survival of excitons as collective, coherent quantum excitations with raising temperature in photosynthetic LH antenna nanoaggregates of purple bacteria is investigated. Apart from fundamental curiosity, this subject is generally important in order to connect the physical research done at cryogenic temperatures on various biological systems with their functioning at physiological temperatures.…”

Section: Discussionmentioning

confidence: 99%

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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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“…19, along with many later works [7][8][9][10][11][12][13][14][15][16][17][18] ). Although such a profile does provide a reasonable approximation to the true form of l R (ω) at low temperatures when the Gaussian and Lorentzian components have similar widths, the approximation breaks down quite seriously when Γ G is much different from √ RΓ L (see below).…”

Section: Derivation Of Lineshape Formulasmentioning

confidence: 97%

Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

Reppert

Kell

Pruitt

et al. 2015

The Journal of Chemical Physics

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The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, ωsp, for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers.

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Emitting Excitonic Polaron States in Core LH1 and Peripheral LH2 Bacterial Light-Harvesting Complexes

Cited by 57 publications

References 31 publications

Fluctuations in the Electron–Phonon Coupling of a Single Chromoprotein

Fluctuations in the Electron–Phonon Coupling of a Single Chromoprotein

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

Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

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