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Arpin PC, Turner DB. Signatures of Vibrational and Electronic Quantum Beats in Femtosecond Coherence Spectra. J Phys Chem A 2021; 125:2425-2435. [PMID: 33724844 PMCID: PMC8023717 DOI: 10.1021/acs.jpca.0c10807] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Indexed: 11/29/2022]
Abstract
Femtosecond laser pulses can produce oscillatory signals in transient-absorption spectroscopy measurements. The quantum beats are often studied using femtosecond coherence spectra (FCS), the Fourier domain amplitude, and phase profiles at individual oscillation frequencies. In principle, one can identify the mechanism that gives rise to each quantum-beat signal by comparing its measured FCS to those arising from microscopic models. To date, however, most measured FCS deviate from the ubiquitous harmonic oscillator model. Here, we expand the inventory of models to which the measured spectra can be compared. We develop quantum-mechanical models of the fundamental, overtone, and combination-band FCS arising from harmonic potentials, the FCS of anharmonic potentials, and the FCS of a purely electronic dimer. This work solidifies the use of FCS for identifying electronic coherences that can arise in measurements of molecular aggregates including photosynthetic proteins. Furthermore, future studies can use the derived expressions to fit the measured FCS and thereby extract microscopic parameters of molecular potential-energy surfaces.
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Affiliation(s)
- Paul C. Arpin
- Department
of Physics, California State University,
Chico, Chico, California 95929, United States
| | - Daniel B. Turner
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
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2
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Janković V, Mančal T. Nonequilibrium steady-state picture of incoherent light-induced excitation harvesting. J Chem Phys 2020; 153:244110. [PMID: 33380098 DOI: 10.1063/5.0029918] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We formulate a comprehensive theoretical description of excitation harvesting in molecular aggregates photoexcited by weak incoherent radiation. An efficient numerical scheme that respects the continuity equation for excitation fluxes is developed to compute the nonequilibrium steady state (NESS) arising from the interplay between excitation generation, excitation relaxation, dephasing, trapping at the load, and recombination. The NESS is most conveniently described in the so-called preferred basis in which the steady-state excitonic density matrix is diagonal. The NESS properties are examined by relating the preferred-basis description to the descriptions in the site or excitonic bases. Focusing on a model photosynthetic dimer, we find that the NESS in the limit of long trapping time is quite similar to the excited-state equilibrium in which the stationary coherences originate from the excitation-environment entanglement. For shorter trapping times, we demonstrate how the properties of the NESS can be extracted from the time-dependent description of an incoherently driven but unloaded dimer. This relation between stationary and time-dependent pictures is valid, provided that the trapping time is longer than the decay time of dynamic coherences accessible in femtosecond spectroscopy experiments.
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Affiliation(s)
- Veljko Janković
- Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Tomáš Mančal
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
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Maiuri M, Brazard J. Electronic Couplings in (Bio-) Chemical Processes. Top Curr Chem (Cham) 2018; 376:10. [DOI: 10.1007/s41061-017-0180-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 12/01/2017] [Indexed: 11/24/2022]
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Ulness DJ, Turner DB. Coherent Two-Quantum Two-Dimensional Electronic Spectroscopy Using Incoherent Light. J Phys Chem A 2017; 121:9211-9220. [PMID: 29120645 DOI: 10.1021/acs.jpca.7b09443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two-quantum two-dimensional electronic spectroscopy (2Q 2D ES) may provide a measure of electron-correlation energies in molecules. Attempts to obtain this profound but elusive signal have relied on experimental implementations using femtosecond laser pulses, which induce an overwhelming background signal of nonresonant response. Here we explore theoretically the signatures of electron correlation in coherent 2Q 2D ES measurements that use spectrally incoherent light, I(4) 2Q 2D ES. One can use such fields to suppress nonresonant response, and therefore this method may better isolate the desired signature of electron correlation. Using an appropriate treatment of the multilevel Bloch electronic system, we find that I(4) 2Q 2D ES presents an opportunity to measure electron-correlation energies in molecules.
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Affiliation(s)
- Darin J Ulness
- Department of Chemistry, Concordia College , Moorhead, Minnesota 56562, United States
| | - Daniel B Turner
- Department of Chemistry, New York University , New York, New York 10003, United States
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Kimberg V, Rohringer N. Stochastic stimulated electronic x-ray Raman spectroscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2016; 3:034101. [PMID: 26958585 PMCID: PMC4752554 DOI: 10.1063/1.4940916] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 01/15/2016] [Indexed: 05/09/2023]
Abstract
Resonant inelastic x-ray scattering (RIXS) is a well-established tool for studying electronic, nuclear, and collective dynamics of excited atoms, molecules, and solids. An extension of this powerful method to a time-resolved probe technique at x-ray free electron lasers (XFELs) to ultimately unravel ultrafast chemical and structural changes on a femtosecond time scale is often challenging, due to the small signal rate in conventional implementations at XFELs that rely on the usage of a monochromator setup to select a small frequency band of the broadband, spectrally incoherent XFEL radiation. Here, we suggest an alternative approach, based on stochastic spectroscopy, which uses the full bandwidth of the incoming XFEL pulses. Our proposed method is relying on stimulated resonant inelastic x-ray scattering, where in addition to a pump pulse that resonantly excites the system a probe pulse on a specific electronic inelastic transition is provided, which serves as a seed in the stimulated scattering process. The limited spectral coherence of the XFEL radiation defines the energy resolution in this process and stimulated RIXS spectra of high resolution can be obtained by covariance analysis of the transmitted spectra. We present a detailed feasibility study and predict signal strengths for realistic XFEL parameters for the CO molecule resonantly pumped at the [Formula: see text] transition. Our theoretical model describes the evolution of the spectral and temporal characteristics of the transmitted x-ray radiation, by solving the equation of motion for the electronic and vibrational degrees of freedom of the system self consistently with the propagation by Maxwell equations.
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Chenu A, Brumer P. Transform-limited-pulse representation of excitation with natural incoherent light. J Chem Phys 2016; 144:044103. [DOI: 10.1063/1.4940028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Aurélia Chenu
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Paul Brumer
- Chemical Physics Theory Group, Department of Chemistry, and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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Chen L, Shenai P, Zheng F, Somoza A, Zhao Y. Optimal Energy Transfer in Light-Harvesting Systems. Molecules 2015; 20:15224-72. [PMID: 26307957 PMCID: PMC6332264 DOI: 10.3390/molecules200815224] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/03/2015] [Accepted: 08/14/2015] [Indexed: 01/25/2023] Open
Abstract
Photosynthesis is one of the most essential biological processes in which specialized pigment-protein complexes absorb solar photons, and with a remarkably high efficiency, guide the photo-induced excitation energy toward the reaction center to subsequently trigger its conversion to chemical energy. In this work, we review the principles of optimal energy transfer in various natural and artificial light harvesting systems. We begin by presenting the guiding principles for optimizing the energy transfer efficiency in systems connected to dissipative environments, with particular attention paid to the potential role of quantum coherence in light harvesting systems. We will comment briefly on photo-protective mechanisms in natural systems that ensure optimal functionality under varying ambient conditions. For completeness, we will also present an overview of the charge separation and electron transfer pathways in reaction centers. Finally, recent theoretical and experimental progress on excitation energy transfer, charge separation, and charge transport in artificial light harvesting systems is delineated, with organic solar cells taken as prime examples.
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Affiliation(s)
- Lipeng Chen
- Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore.
| | - Prathamesh Shenai
- Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore.
| | - Fulu Zheng
- Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore.
| | - Alejandro Somoza
- Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore.
| | - Yang Zhao
- Division of Materials Science, Nanyang Technological University, 50 Nanyang Avenue,Singapore 639798, Singapore.
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Ulness DJ, Turner DB. Lineshape analysis of coherent multidimensional optical spectroscopy using incoherent light. J Chem Phys 2015; 142:212420. [DOI: 10.1063/1.4917320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Coherent multidimensional optical spectra measured using incoherent light. Nat Commun 2014; 4:2298. [PMID: 23985989 DOI: 10.1038/ncomms3298] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 07/11/2013] [Indexed: 11/09/2022] Open
Abstract
Four-wave mixing measurements can reveal spectral and dynamics information that is hidden in linear spectra by the interactions among light-absorbing molecules and with their environment. Coherent multidimensional optical spectroscopy is an important variant of four-wave mixing because it resolves a map of interactions and correlations between absorption bands. Previous coherent multidimensional optical spectroscopy measurements have used femtosecond pulses with great success, and it may seem that femtosecond pulses are necessary for such measurements. Here we present coherent two-dimensional electronic spectra measured using incoherent light. The spectra of model molecular systems using broadband spectrally incoherent light are similar but not identical to those expected from measurements using femtosecond pulses. Specifically, the spectra show particular sensitivity to long-lived intermediates such as photoisomers. The results will motivate the design of similar experiments in spectral ranges where femtosecond pulses are difficult to produce.
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Fassioli F, Dinshaw R, Arpin PC, Scholes GD. Photosynthetic light harvesting: excitons and coherence. J R Soc Interface 2014; 11:20130901. [PMID: 24352671 PMCID: PMC3899860 DOI: 10.1098/rsif.2013.0901] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/29/2013] [Indexed: 12/15/2022] Open
Abstract
Photosynthesis begins with light harvesting, where specialized pigment-protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.
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Affiliation(s)
| | | | | | - Gregory D. Scholes
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, Ontario, CanadaM5S 3H6
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Chandra K, Schlagnitweit J, Wohlschlager C, Jerschow A, Müller N. Spin-Noise-Detected Two-Dimensional Fourier-Transform NMR Spectroscopy. J Phys Chem Lett 2013; 4:3853-3856. [PMID: 24294412 PMCID: PMC3843499 DOI: 10.1021/jz402100g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 10/29/2013] [Indexed: 05/13/2023]
Abstract
We introduce two-dimensional NMR spectroscopy detected by recording and processing the noise originating from nuclei that have not been subjected to any radio frequency excitation. The method relies on cross-correlation of two noise blocks that bracket the evolution and mixing periods. While the sensitivity of the experiment is low in conventional NMR setups, spin-noise-detected NMR spectroscopy has great potential for use with extremely small numbers of spins, thereby opening a way to nanoscale multidimensional NMR spectroscopy.
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Affiliation(s)
- Kousik Chandra
- Institute of Organic Chemistry and Scientific Computing Department, Johannes Kepler University Linz, Altenbergerstraße 69, Linz 4040, Austria
| | - Judith Schlagnitweit
- Institute of Organic Chemistry and Scientific Computing Department, Johannes Kepler University Linz, Altenbergerstraße 69, Linz 4040, Austria
| | - Christian Wohlschlager
- Institute of Organic Chemistry and Scientific Computing Department, Johannes Kepler University Linz, Altenbergerstraße 69, Linz 4040, Austria
| | - Alexej Jerschow
- Department of Chemistry, New York University, 100 Washington Square East, New York 10003, United States
| | - Norbert Müller
- Institute of Organic Chemistry and Scientific Computing Department, Johannes Kepler University Linz, Altenbergerstraße 69, Linz 4040, Austria
- E-mail: . Phone: +43 732 2468 8746
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