Dichotomous Disorder versus Excitonic Splitting of the B800 Band of <i>Allochromatium vinosum</i>

Kell, Adam; Khmelnitskiy, Anton; Jassas, Mahboobe; Jankowiak, Ryszard

doi:10.1021/acs.jpclett.8b01584

Cited by 4 publications

(5 citation statements)

References 13 publications

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“…Analogously, a study of LH2 isolated from Allochromatium vinosum, which contains 24 B850 bacteriochlorophyll molecules, shows that at T = 30 fs, the upper cross-peak interpreted as a dominantly GSB signal is completely cancelled out by the ESA signal . However, a lower GSB cross-peak is present at early times for electronic couplings as small as ∼20 cm –1 …”

Section: Introductionmentioning

confidence: 88%

“…40 However, a lower GSB cross-peak is present at early times for electronic couplings as small as ∼20 cm –1 . 54…”

Section: Introductionmentioning

confidence: 99%

“…40 However, a lower GSB cross-peak is present at early times for electronic couplings as small as ∼20 cm −1 . 54 Apart from the abovementioned 2DES studies, early pumpprobe studies of isolated LH2 complexes extracted from a number of species of purple bacteria show simultaneous bleaching of B800 and B850 bands at early waiting times after excitation of the B800 band. One-and two-color femtosecond pump-probe studies on LH2 complexes isolated from Rhodobacter sphaeroides and R. palustris at room temperature and 77 K revealed GSB signals at short pump-probe delays when probing the B800 and B850 bands upon B800 band excitation.…”

Section: ■ Introductionmentioning

confidence: 99%

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Simulating Fluorescence-Detected Two-Dimensional Electronic Spectroscopy of Multichromophoric Systems

et al. 2018

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We present a theory for modeling fluorescence-detected two-dimensional electronic spectroscopy of multichromophoric systems. The theory is tested by comparison of the predicted spectra of the light-harvesting complex LH2 with experimental data. A qualitative explanation of the strong cross-peaks as compared to conventional two-dimensional electronic spectra is given. The strong cross-peaks are attributed to the clean ground-state signal that is revealed when the annihilation of exciton pairs created on the same LH2 complex cancels oppositely signed signals from the doubly excited state. This annihilation process occurs much faster than the nonradiative relaxation. Furthermore, the line shape difference is attributed to slow dynamics, exciton delocalization within the bands, and intraband exciton–exciton annihilation. This is in line with existing theories presented for model systems. We further propose the use of time-resolved fluorescence-detected two-dimensional spectroscopy to study state-resolved exciton–exciton annihilation.

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Section: Introductionmentioning

confidence: 88%

“…40 However, a lower GSB cross-peak is present at early times for electronic couplings as small as ∼20 cm –1 . 54…”

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Simulating Fluorescence-Detected Two-Dimensional Electronic Spectroscopy of Multichromophoric Systems

et al. 2018

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“…This is in contrast with the coupling to phonons, which rather dramatically enhances in LH2 and LH1 complexes. In theory, both the vibrational and electron-phonon couplings are expected to decrease with increasing exciton coupling [153][154][155]. The unexpected boost of the electron-phonon coupling was explained in [142] by exciton self-trapping, promoted by mixing of molecular exciton states with the charge transfer states between the adjacent chromophores in the tightly packed B850 and B875 arrangements.…”

Section: Modifications Of the Vibrational Structure And Electron-phon...mentioning

confidence: 99%

Chlorophyll spectroscopy: conceptual basis, modern high-resolution approaches, and current challenges

Freiberg¹,

Linnanto²,

Rätsep³

et al. 2022

PEAS

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The conceptual formalism to understand the properties and function of chlorophylls in the gas and solution phases as well as in protein matrices is reviewed. This formalism is then applied to interpret modern high-resolution spectroscopic data, resulting from methods such as differential fluorescence line-narrowing spectroscopy and selective fluorescence excitation spectroscopy, which resolve individual vibrational transitions within the inhomogeneously broadened emission and absorption spectra of chlorophyll-a, bacteriochlorophyll-a, and pheophytin-a. Density functional theory and ab initio quantum chemical calculations are applied to interpret this data and fill in missing information needed to understand photosynthetic processes. The focus is placed on recognizing environmental and thermal effects, as well as the roles of Duschinsky rotation and non-adiabatic coupling in controlling the spectra. A critical feature of chlorophyll spectroscopy is determined to be absorption-emission asymmetry. Its ramifications for chlorophyll's function in photosystems are expected to be significant, as most current models for understanding their function assume that absorption and emission are symmetric, i.e. in the absence of relaxation processes, molecules coherently re-emit the light that they absorbed to enact exciton transport. The effect of the Duschinsky rotation is that after vibrational excitation during the electronic transition chlorophylls mostly emit light at different energies to what they absorb, while the effect of non-adiabatic coupling is that the polarization of the light is changed.

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“…Indeed, LH2 has been one of the most widely studied photosynthetic antenna complexes with both theories and experiments due to its high quantum efficiency and its interesting coupling behaviors with its 9-fold symmetry (Figure ). − Thus, the ability of constructing a reliable PES itself will have potential to bring new insights into the system itself. We will also discuss the general implication of this work toward constructing IM PES of other protein-embedded systems, for which no preexisting databases are available in the beginning.…”

Section: Introductionmentioning

confidence: 99%

Efficiently Transplanting Potential Energy Interpolation Database between Two Systems: Bacteriochlorophyll Case with FMO and LH2 Complexes

Cho

Chung

Rhee

2019

J. Chem. Inf. Model.

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Generating a reliable potential energy surface (PES) is an important issue for studying the dynamics of any system with computational simulations. Interpolation mechanics/molecular mechanics (IM/MM) based on a PES interpolation scheme is a useful tool in that regard as it provides an accuracy of a quantum chemistry (QC) level while maintaining its computational cost comparable to conventional MM force fields. Despite this benefit, constructing the database for interpolation itself is still challenging and time-consuming. Here, we present a method with which we can construct the IM database of one system based on a preexisting data set for another related system. We adopt the case of constructing bacteriochlorophyll PESs for the light-harvesting 2 (LH2) complex by utilizing already available IM database for the BChls from the Fenna–Matthews–Olson (FMO) complex. In this method, the IM database from FMO is first transplanted to LH2 by considering BChl displacement vectors that take into account the geometry differences induced by the protein scaffolds. From this transplanted primitive database entries, a relatively small number of effective ones are selected by a survival process based on a genetic algorithm such that the IM energies evaluated at geometries in a conveniently collected prediction set can closely match with the reference QC energies. The selection process is expedited by using two different levels of basis sets for the QC calculations. To demonstrate the utility of the PES thus constructed, we carry out 1 ns of IM/MM dynamics simulations with the finally optimized BChl database for LH2. Indeed, the energy profiles of the snapshots are found to be closely matching with the reference QC calculation data, with only ∼0.07 eV of errors in the ground- and excited-state energies and ∼0.008 eV of errors in the transition energies. We also show that properly selecting data points is actually quite important for generating an IM PES toward performing molecular dynamics simulations.

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Dichotomous Disorder versus Excitonic Splitting of the B800 Band of Allochromatium vinosum

Cited by 4 publications

References 13 publications

Simulating Fluorescence-Detected Two-Dimensional Electronic Spectroscopy of Multichromophoric Systems

Simulating Fluorescence-Detected Two-Dimensional Electronic Spectroscopy of Multichromophoric Systems

Chlorophyll spectroscopy: conceptual basis, modern high-resolution approaches, and current challenges

Efficiently Transplanting Potential Energy Interpolation Database between Two Systems: Bacteriochlorophyll Case with FMO and LH2 Complexes

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