Classification of Coherent Enhancements of Light-Harvesting Processes

Tomasi, Stefano; Kassal, Ivan

doi:10.1021/acs.jpclett.9b03490

Cited by 38 publications

(48 citation statements)

References 69 publications

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“…Kassal et al 39,112 have drawn attention on this interesting property in recent reports about a two-site excitonic system with orthogonal transition dipoles in which an enhancement of excitation transfer should be possible by exciting a left or right donor site, i.e., by preparing a particular superposition of the delocalized eigenstates. This situation with orthogonal dipoles differs from the case with alignment of the transition dipole moments, which is a condition for long-lived quasi stationary coherence in a V-type system driven by incoherent light 32 .…”

Section: Discussionmentioning

confidence: 99%

Funneling dynamics in a phenylacetylene trimer: Coherent excitation of donor excitonic states and their superposition

Breuil

Mangaud

Lasorne

et al. 2021

The Journal of Chemical Physics

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Funneling dynamics in conjugated dendrimers has raised great interest in the context of artificial light-harvesting processes. Photoinduced relaxation has been explored by time-resolved spectroscopy and simulations, mainly by semiclassical approaches or referring to open quantum systems methods, within the Redfield approximation. Here, we take the benefit of an ab initio investigation of a phenylacetylene trimer, and in the spirit of a divide-and-conquer approach, we focus on the early dynamics of the hierarchy of interactions. We build a simplified but realistic model by retaining only bright electronic states and selecting the vibrational domain expected to play the dominant role for timescales shorter than 500 fs. We specifically analyze the role of the in-plane high-frequency skeletal vibrational modes involving the triple bonds. Open quantum system non-adiabatic dynamics involving conical intersections is conducted by separating the electronic subsystem from the high-frequency tuning and coupling vibrational baths. This partition is implemented within a robust non-perturbative and non-Markovian method, here the hierarchical equations of motion. We will more precisely analyze the coherent preparation of donor states or of their superposition by short laser pulses with different polarizations. In particular, we extend the π-pulse strategy for the creation of a superposition to a V-type system. We study the relaxation induced by the high-frequency vibrational collective modes and the transitory dissymmetry, which results from the creation of a superposition of electronic donor states.

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Section: Discussionmentioning

confidence: 99%

Funneling dynamics in a phenylacetylene trimer: Coherent excitation of donor excitonic states and their superposition

Breuil

Mangaud

Lasorne

et al. 2021

The Journal of Chemical Physics

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show abstract

“…There has been much debate surrounding the extent to which natural photosynthetic systems may have evolved in order to harness quantum coherence (of various types) as a means to improve efficiency [4][5][6][7][8][9]; but, in any case, clear advantages of utilizing quantum effects have been predicted in artificial devices [10][11][12][13][14][15][16]. These results provide ample motivation for further investigation into function and efficiency of nanoscale transport processes at a level that includes quantum mechanical interference.…”

Section: Introductionmentioning

confidence: 99%

Eliminating radiative losses in long-range exciton transport

Davidson,

Pollock,

Gauger

2022

Preprint

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We demonstrate that it is possible to effectively eliminate radiative losses during excitonic energy transport in systems with an intrinsic energy gradient. By considering chain-like systems of repeating 'unit' cells which can each consist of multiple sites, we show that tuning a single system parameter (the intra-unit-cell coupling) leads to efficient and highly robust transport over relatively long distances. This remarkable transport performance is shown to originate from a partitioning of the system's eigenstates into energetically-separated bright and dark subspaces, allowing long range transport to proceed efficiently through a 'dark chain' of eigenstates. Finally, we discuss the effects of intrinsic dipole moments, which are of particular relevance to molecular architectures, and demonstrate that appropriately-aligned dipoles can lead to additional protection against other (non-radiative) loss processes. Our dimensionless open quantum systems model is designed to be broadly applicable to a range of experimental platforms.

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“…For groundstate vibrations, only relatively recently has the differential fluorescence line-narrowing techniques ( FLN) Freiberg, 2003, 2007;Rätsep et al, 2009aRätsep et al, , 2019a been developed to deliver similar results. These techniques provide critical vibrational data required for studies of, e.g., coherent energy transport in photosystems (Renger et al, 1996;Huo and Coker, 2010;Rivera et al, 2013;Kreisbeck et al, 2014;Müh et al, 2014;Romero et al, 2014;Malý et al, 2016;Duan et al, 2017;Ren et al, 2018;Cao et al, 2020;Tomasi and Kassal, 2020).…”

Section: Introductionmentioning

confidence: 99%

Asymmetry in the Qy Fluorescence and Absorption Spectra of Chlorophyll a Pertaining to Exciton Dynamics

2020

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Significant asymmetry found between the high-resolution Qy emission and absorption spectra of chlorophyll-a is herein explained, providing basic information needed to understand photosynthetic exciton transport and photochemical reactions. The Qy spectral asymmetry in chlorophyll has previously been masked by interference in absorption from the nearby Qx transition, but this effect has recently been removed using extensive quantum spectral simulations or else by analytical inversion of absorption and magnetic circular dichroism data, allowing high-resolution absorption information to be accurately determined from fluorescence-excitation spectra. To compliment this, here, we measure and thoroughly analyze the high-resolution differential fluorescence line narrowing spectra of chlorophyll-a in trimethylamine and in 1-propanol. The results show that vibrational frequencies often change little between absorption and emission, yet large changes in line intensities are found, this effect also being strongly solvent dependent. Among other effects, the analysis in terms of four basic patterns of Duschinsky-rotation matrix elements, obtained using CAM-B3LYP calculations, predicts that a chlorophyll-a molecule excited into a specific vibrational level, may, without phase loss or energy relaxation, reemit the light over a spectral bandwidth exceeding 1,000 cm−1 (0.13 eV) to influence exciton-transport dynamics.

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Classification of Coherent Enhancements of Light-Harvesting Processes

Cited by 38 publications

References 69 publications

Funneling dynamics in a phenylacetylene trimer: Coherent excitation of donor excitonic states and their superposition

Funneling dynamics in a phenylacetylene trimer: Coherent excitation of donor excitonic states and their superposition

Eliminating radiative losses in long-range exciton transport

Asymmetry in the Qy Fluorescence and Absorption Spectra of Chlorophyll a Pertaining to Exciton Dynamics

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