1
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Sun K, Ribeiro RF. Theoretical formulation of chemical equilibrium under vibrational strong coupling. Nat Commun 2024; 15:2405. [PMID: 38493189 PMCID: PMC10944518 DOI: 10.1038/s41467-024-46442-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 02/28/2024] [Indexed: 03/18/2024] Open
Abstract
Experiments have suggested that strong interactions between molecular ensembles and infrared microcavities can be employed to control chemical equilibria. Nevertheless, the primary mechanism and key features of the effect remain largely unexplored. In this work, we develop a theory of chemical equilibrium in optical microcavities, which allows us to relate the equilibrium composition of a mixture in different electromagnetic environments. Our theory shows that in planar microcavities under strong coupling with polyatomic molecules, hybrid modes formed between all dipole-active vibrations and cavity resonances contribute to polariton-assisted chemical equilibrium shifts. To illustrate key aspects of our formalism, we explore a model SN2 reaction within a single-mode infrared resonator. Our findings reveal that chemical equilibria can be shifted towards either direction of a chemical reaction, depending on the oscillator strength and frequencies of reactant and product normal modes. Polariton-induced zero-point energy changes provide the dominant contributions, though the effects in idealized single-mode cavities tend to diminish quickly as the temperature and number of molecules increase. Our approach is valid in generic electromagnetic environments and paves the way for understanding and controlling chemical equilibria with microcavities.
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Affiliation(s)
- Kaihong Sun
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, GA, 30322, USA
| | - Raphael F Ribeiro
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, GA, 30322, USA.
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2
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Xiang B, Xiong W. Molecular Polaritons for Chemistry, Photonics and Quantum Technologies. Chem Rev 2024; 124:2512-2552. [PMID: 38416701 PMCID: PMC10941193 DOI: 10.1021/acs.chemrev.3c00662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 01/22/2024] [Accepted: 02/08/2024] [Indexed: 03/01/2024]
Abstract
Molecular polaritons are quasiparticles resulting from the hybridization between molecular and photonic modes. These composite entities, bearing characteristics inherited from both constituents, exhibit modified energy levels and wave functions, thereby capturing the attention of chemists in the past decade. The potential to modify chemical reactions has spurred many investigations, alongside efforts to enhance and manipulate optical responses for photonic and quantum applications. This Review centers on the experimental advances in this burgeoning field. Commencing with an introduction of the fundamentals, including theoretical foundations and various cavity architectures, we discuss outcomes of polariton-modified chemical reactions. Furthermore, we navigate through the ongoing debates and uncertainties surrounding the underpinning mechanism of this innovative method of controlling chemistry. Emphasis is placed on gaining a comprehensive understanding of the energy dynamics of molecular polaritons, in particular, vibrational molecular polaritons─a pivotal facet in steering chemical reactions. Additionally, we discuss the unique capability of coherent two-dimensional spectroscopy to dissect polariton and dark mode dynamics, offering insights into the critical components within the cavity that alter chemical reactions. We further expand to the potential utility of molecular polaritons in quantum applications as well as precise manipulation of molecular and photonic polarizations, notably in the context of chiral phenomena. This discussion aspires to ignite deeper curiosity and engagement in revealing the physics underpinning polariton-modified molecular properties, and a broad fascination with harnessing photonic environments to control chemistry.
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Affiliation(s)
- Bo Xiang
- Department
of Chemistry, School of Science and Research Center for Industries
of the Future, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Wei Xiong
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92126, United States
- Materials
Science and Engineering Program, University
of California, San Diego, California 92126, United States
- Department
of Electrical and Computer Engineering, University of California, San
Diego, California 92126, United States
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3
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Parolin G, Peruffo N, Mancin F, Collini E, Corni S. Molecularly Detailed View of Strong Coupling in Supramolecular Plexcitonic Nanohybrids. NANO LETTERS 2024; 24:2273-2281. [PMID: 38261782 DOI: 10.1021/acs.nanolett.3c04514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Plexcitons constitute a peculiar example of light-matter hybrids (polaritons) originating from the (strong) coupling of plasmonic modes and molecular excitations. Here we propose a fully quantum approach to model plexcitonic systems and test it against existing experiments on peculiar hybrids formed by Au nanoparticles and a well-known porphyrin derivative, involving the Q branch of the organic dye absorption spectrum. Our model extends simpler descriptions of polaritonic systems to account for the multilevel structure of the dyes, spatially varying interactions with a given plasmon mode, and the simultaneous occurrence of plasmon-molecule and intermolecular interactions. By keeping a molecularly detailed view, we were able to gain insights into the local structure and individual contributions to the resulting plexcitons. Our model can be applied to rationalize and predict energy funneling toward specific molecular sites within a plexcitonic assembly, which is highly valuable for designing and controlling chemical transformations in the new polaritonic landscapes.
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Affiliation(s)
- Giovanni Parolin
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Nicola Peruffo
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Fabrizio Mancin
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
| | - Elisabetta Collini
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Padua Quantum Technologies Research Center, University of Padova, 35131 Padova, Italy
| | - Stefano Corni
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
- Padua Quantum Technologies Research Center, University of Padova, 35131 Padova, Italy
- CNR Institute of Nanoscience, 41125 Modena, Italy
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4
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Rolczynski BS, Díaz SA, Goldman ER, Medintz IL, Melinger JS. Investigating the dissipation of heat and quantum information from DNA-scaffolded chromophore networks. J Chem Phys 2024; 160:034105. [PMID: 38230810 DOI: 10.1063/5.0181034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/15/2023] [Indexed: 01/18/2024] Open
Abstract
Scaffolded molecular networks are important building blocks in biological pigment-protein complexes, and DNA nanotechnology allows analogous systems to be designed and synthesized. System-environment interactions in these systems are responsible for important processes, such as the dissipation of heat and quantum information. This study investigates the role of nanoscale molecular parameters in tuning these vibronic system-environment dynamics. Here, genetic algorithm methods are used to obtain nanoscale parameters for a DNA-scaffolded chromophore network based on comparisons between its calculated and measured optical spectra. These parameters include the positions, orientations, and energy level characteristics within the network. This information is then used to compute the dynamics, including the vibronic population dynamics and system-environment heat currents, using the hierarchical equations of motion. The dissipation of quantum information is identified by the system's transient change in entropy, which is proportional to the heat currents according to the second law of thermodynamics. These results indicate that the dissipation of quantum information is highly dependent on the particular nanoscale characteristics of the molecular network, which is a necessary first step before gleaning the systematic optimization rules. Subsequently, the I-concurrence dynamics are calculated to understand the evolution of the vibronic system's quantum entanglement, which are found to be long-lived compared to these system-bath dissipation processes.
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Affiliation(s)
- Brian S Rolczynski
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Sebastián A Díaz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Ellen R Goldman
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Igor L Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Joseph S Melinger
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
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5
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Scholes GD. Large Coherent States Formed from Disordered k-Regular Random Graphs. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1519. [PMID: 37998211 PMCID: PMC10670866 DOI: 10.3390/e25111519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/01/2023] [Accepted: 11/03/2023] [Indexed: 11/25/2023]
Abstract
The present work is motivated by the need for robust, large-scale coherent states that can play possible roles as quantum resources. A challenge is that large, complex systems tend to be fragile. However, emergent phenomena in classical systems tend to become more robust with scale. Do these classical systems inspire ways to think about robust quantum networks? This question is studied by characterizing the complex quantum states produced by mapping interactions between a set of qubits from structure in graphs. We focus on maps based on k-regular random graphs where many edges were randomly deleted. We ask how many edge deletions can be tolerated. Surprisingly, it was found that the emergent coherent state characteristic of these graphs was robust to a substantial number of edge deletions. The analysis considers the possible role of the expander property of k-regular random graphs.
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Affiliation(s)
- Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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6
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Mandal A, Taylor MA, Weight BM, Koessler ER, Li X, Huo P. Theoretical Advances in Polariton Chemistry and Molecular Cavity Quantum Electrodynamics. Chem Rev 2023; 123:9786-9879. [PMID: 37552606 PMCID: PMC10450711 DOI: 10.1021/acs.chemrev.2c00855] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Indexed: 08/10/2023]
Abstract
When molecules are coupled to an optical cavity, new light-matter hybrid states, so-called polaritons, are formed due to quantum light-matter interactions. With the experimental demonstrations of modifying chemical reactivities by forming polaritons under strong light-matter interactions, theorists have been encouraged to develop new methods to simulate these systems and discover new strategies to tune and control reactions. This review summarizes some of these exciting theoretical advances in polariton chemistry, in methods ranging from the fundamental framework to computational techniques and applications spanning from photochemistry to vibrational strong coupling. Even though the theory of quantum light-matter interactions goes back to the midtwentieth century, the gaps in the knowledge of molecular quantum electrodynamics (QED) have only recently been filled. We review recent advances made in resolving gauge ambiguities, the correct form of different QED Hamiltonians under different gauges, and their connections to various quantum optics models. Then, we review recently developed ab initio QED approaches which can accurately describe polariton states in a realistic molecule-cavity hybrid system. We then discuss applications using these method advancements. We review advancements in polariton photochemistry where the cavity is made resonant to electronic transitions to control molecular nonadiabatic excited state dynamics and enable new photochemical reactivities. When the cavity resonance is tuned to the molecular vibrations instead, ground-state chemical reaction modifications have been demonstrated experimentally, though its mechanistic principle remains unclear. We present some recent theoretical progress in resolving this mystery. Finally, we review the recent advances in understanding the collective coupling regime between light and matter, where many molecules can collectively couple to a single cavity mode or many cavity modes. We also lay out the current challenges in theory to explain the observed experimental results. We hope that this review will serve as a useful document for anyone who wants to become familiar with the context of polariton chemistry and molecular cavity QED and thus significantly benefit the entire community.
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Affiliation(s)
- Arkajit Mandal
- Department
of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Michael A.D. Taylor
- The
Institute of Optics, Hajim School of Engineering, University of Rochester, Rochester, New York 14627, United States
| | - Braden M. Weight
- Department
of Physics and Astronomy, University of
Rochester, Rochester, New York 14627, United
States
| | - Eric R. Koessler
- Department
of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - Xinyang Li
- Department
of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
- Theoretical
Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Pengfei Huo
- Department
of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
- The
Institute of Optics, Hajim School of Engineering, University of Rochester, Rochester, New York 14627, United States
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7
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Aroeira GJR, Kairys KT, Ribeiro RF. Theoretical Analysis of Exciton Wave Packet Dynamics in Polaritonic Wires. J Phys Chem Lett 2023:5681-5691. [PMID: 37314883 DOI: 10.1021/acs.jpclett.3c01082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We present a comprehensive study of the exciton wave packet evolution in disordered lossless polaritonic wires. Our simulations reveal signatures of ballistic, diffusive, and subdiffusive exciton dynamics under strong light-matter coupling and identify the typical time scales associated with the transitions between these qualitatively distinct transport phenomena. We determine optimal truncations of the matter and radiation subsystems required for generating reliable time-dependent data from computational simulations at an affordable cost. The time evolution of the photonic part of the wave function reveals that many cavity modes contribute to the dynamics in a nontrivial fashion. Hence, a sizable number of photon modes is needed to describe exciton propagation with a reasonable accuracy. We find and discuss an intriguingly common lack of dominance of the photon mode on resonance with matter in both the presence and absence of disorder. We discuss the implications of our investigations for the development of theoretical models and analysis of experiments where coherent intermolecular energy transport and static disorder play an important role.
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Affiliation(s)
- Gustavo J R Aroeira
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Kyle T Kairys
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Raphael F Ribeiro
- Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
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8
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Sauerwein N, Orsi F, Uhrich P, Bandyopadhyay S, Mattiotti F, Cantat-Moltrecht T, Pupillo G, Hauke P, Brantut JP. Engineering random spin models with atoms in a high-finesse cavity. NATURE PHYSICS 2023; 19:1128-1134. [PMID: 37575364 PMCID: PMC10415180 DOI: 10.1038/s41567-023-02033-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 03/23/2023] [Indexed: 08/15/2023]
Abstract
All-to-all interacting, disordered quantum many-body models have a wide range of applications across disciplines, from spin glasses in condensed-matter physics over holographic duality in high-energy physics to annealing algorithms in quantum computing. Typically, these models are abstractions that do not find unambiguous physical realizations in nature. Here we realize an all-to-all interacting, disordered spin system by subjecting an atomic cloud in a cavity to a controllable light shift. Adjusting the detuning between atom resonance and cavity mode, we can tune between disordered versions of a central-mode model and a Lipkin-Meshkov-Glick model. By spectroscopically probing the low-energy excitations of the system, we explore the competition of interactions with disorder across a broad parameter range. We show how disorder in the central-mode model breaks the strong collective coupling, making the dark-state manifold cross over to a random distribution of weakly mixed light-matter, 'grey', states. In the Lipkin-Meshkov-Glick model, the ferromagnetic finite-sized ground state evolves towards a paramagnet as disorder is increased. In that regime, semi-localized eigenstates emerge, as we observe by extracting bounds on the participation ratio. These results present substantial steps towards freely programmable cavity-mediated interactions for the design of arbitrary spin Hamiltonians.
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Affiliation(s)
- Nick Sauerwein
- Institute of Physics and Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Francesca Orsi
- Institute of Physics and Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Philipp Uhrich
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
| | - Soumik Bandyopadhyay
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
| | - Francesco Mattiotti
- University of Strasbourg and CNRS, CESQ and ISIS (UMR 7006), aQCess, Strasbourg, France
| | - Tigrane Cantat-Moltrecht
- Institute of Physics and Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Guido Pupillo
- University of Strasbourg and CNRS, CESQ and ISIS (UMR 7006), aQCess, Strasbourg, France
| | - Philipp Hauke
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
| | - Jean-Philippe Brantut
- Institute of Physics and Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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9
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Xiong W. Molecular Vibrational Polariton Dynamics: What Can Polaritons Do? Acc Chem Res 2023; 56:776-786. [PMID: 36930582 PMCID: PMC10077590 DOI: 10.1021/acs.accounts.2c00796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
ConspectusWhen molecular vibrational modes strongly couple to virtual states of photonic modes, new molecular vibrational polariton states are formed, along with a large population of dark reservoir modes. The polaritons are much like the bonding and antibonding molecular orbitals when atomic orbitals form molecular bonds, while the dark modes are like nonbonding orbitals. Because the polariton states are half-matter and half-light, whose energy is shifted from the parental states, polaritons are predicted to modify chemistry under thermally activated conditions, leading to an exciting and emerging field known as polariton chemistry that could potentially shift paradigms in chemistry. Despite several published results supporting this concept, the chemical physics and mechanism of polariton chemistry remain elusive. One reason for this challenge is that previous works cannot differentiate polaritons from dark modes. This limitation makes delineating the contributions to chemistry from polaritons and dark states difficult. However, this level of insight is critical for developing a solid mechanism for polariton chemistry to design and predict the outcome of strong coupling with any given reaction. My group addressed the challenge of differentiating the dynamics of polaritons and dark modes by ultrafast two-dimensional infrared (2D IR) spectroscopy. Specifically, (1) we found that polaritons can facilitate intra- and intermolecular vibrational energy transfer, opening a pathway to control vibrational energy flow in liquid-phase molecular systems, and (2) by studying a single-step isomerization event, we verified that indeed polaritons can modify chemical dynamics under strong coupling conditions, but in contrast, the dark modes behave like uncoupled molecules and do not change the dynamics. This finding confirmed the central concept of polariton chemistry: polaritons modify the potential energy landscape of reactions. The result also clarified the role of dark modes, which lays a critical foundation for designing cavities for future polariton chemistry. Aside from using 2D IR spectroscopy to study polariton chemistry, we also used the same technique to develop molecular polaritons into a potential quantum simulation platform. We demonstrated that polaritons have Rabi oscillations, and using a checkerboard cavity design, we showed that polaritons could have large nonlinearity across space. We further used the checkerboard polaritons to simulate coherence transfer and visualize it. A unidirectional coherence transfer was observed, indicating non-Hermitian dynamics. The highlighted efforts in this Account provide a solid understanding of the capability of polaritons for chemistry and quantum information science. I conclude this Account by discussing a few challenges for moving polariton chemistry toward being predictable and making the polariton quantum platform a complement to existing systems.
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Affiliation(s)
- Wei Xiong
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
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10
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Hu W, Gustin I, Krauss TD, Franco I. Tuning and Enhancing Quantum Coherence Time Scales in Molecules via Light-Matter Hybridization. J Phys Chem Lett 2022; 13:11503-11511. [PMID: 36469838 PMCID: PMC9761670 DOI: 10.1021/acs.jpclett.2c02877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
Protecting quantum coherences in matter from the detrimental effects introduced by its environment is essential to employ molecules and materials in quantum technologies and develop enhanced spectroscopies. Here, we show how dressing molecular chromophores with quantum light in the context of optical cavities can be used to generate quantum superposition states with tunable coherence time scales that are longer than those of the bare molecule, even at room temperature and for molecules immersed in solvent. For this, we develop a theory of decoherence rates for molecular polaritonic states and demonstrate that quantum superpositions that involve such hybrid light-matter states can survive for times that are orders of magnitude longer than those of the bare molecule while remaining optically controllable. Further, by studying these tunable coherence enhancements in the presence of lossy cavities, we demonstrate that they can be enacted using present-day optical cavities. The analysis offers a viable strategy to engineer and increase quantum coherence lifetimes in molecules.
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Affiliation(s)
- Wenxiang Hu
- Materials
Science Program, University of Rochester, Rochester, New York14627, United States
| | - Ignacio Gustin
- Department
of Chemistry, University of Rochester, Rochester, New York14627, United States
| | - Todd D. Krauss
- Department
of Chemistry, University of Rochester, Rochester, New York14627, United States
- Institute
of Optics, University of Rochester, Rochester, New York14627, United States
| | - Ignacio Franco
- Department
of Chemistry, University of Rochester, Rochester, New York14627, United States
- Department
of Physics, University of Rochester, Rochester, New York14627, United States
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11
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Chen TT, Du M, Yang Z, Yuen-Zhou J, Xiong W. Cavity-enabled enhancement of ultrafast intramolecular vibrational redistribution over pseudorotation. Science 2022; 378:790-794. [DOI: 10.1126/science.add0276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vibrational strong coupling (VSC) between molecular vibrations and microcavity photons yields a few polaritons (light-matter modes) and many dark modes (with negligible photonic character). Although VSC is reported to alter thermally activated chemical reactions, its mechanisms remain opaque. To elucidate this problem, we followed ultrafast dynamics of a simple unimolecular vibrational energy exchange in iron pentacarbonyl [Fe(CO)
5
] under VSC, which showed two competing channels: pseudorotation and intramolecular vibrational-energy redistribution (IVR). We found that under polariton excitation, energy exchange was overall accelerated, with IVR becoming faster and pseudorotation being slowed down. However, dark-mode excitation revealed unchanged dynamics compared with those outside of the cavity, with pseudorotation dominating. Thus, despite controversies around thermally activated VSC modified chemistry, our work shows that VSC can indeed alter chemistry through a nonequilibrium preparation of polaritons.
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Affiliation(s)
- Teng-Teng Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Matthew Du
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Zimo Yang
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Wei Xiong
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
- Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA, USA
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12
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Scholes GD. The Kuramoto–Lohe model and collective absorption of a photon. Proc Math Phys Eng Sci 2022. [DOI: 10.1098/rspa.2022.0377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Light absorption by molecular exciton states in disordered networks is studied. The main purpose of this paper is to look at how phases of the intermediate ground–excited state superposition interfere during the absorption process. How does this phase average enable, or suppress, absorption to a delocalized state? To address this question, a theory for phase oscillators is used to predict the purity of the collective excited state of the network. The results of the study suggest that collective absorption by molecular exciton states requires a sufficiently large electronic coupling between molecules in the network compared to the random distribution of transition energies at the sites, even when the molecular network is completely isolated from the environment degrees of freedom. The ‘dividing line’ between absorption to a mixture of, essentially, localized excited states and coherent excitation of a pure delocalized exciton state is suggested to be predicted by the threshold of phase synchronization.
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13
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Salam A. Two bridge-particle-mediated RET between chiral molecules. J Chem Phys 2022; 157:104110. [DOI: 10.1063/5.0105172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The problem of resonance energy transfer between a pair of chiral molecules mediated by two electrically polarizable bridging particles is solved using molecular QED theory. In this framework a single virtual photon propagates between any two-coupled entities and is responsible for the conveyance of excitation energy from emitter to absorber. Electric dipole and quadrupole, and magnetic dipole couplings linear in the Maxwell fields are employed for donor and acceptor, while each mediator scatters two virtual photons and responds quadratically to the electric displacement field via its electric dipole polarizability. This enables fourth-order diagrammatic perturbation theory to be used to compute the probability amplitude for the process. Individual multipole moment contributions to the Fermi golden rule rate are then extracted for oriented and isotropic systems. Discriminatory transfer rates arise when either the donor or the acceptor are electric-magnetic dipole and the other has a pure multipole moment, or when both are chiral, with mixed electric dipole-quadrupole contributions vanishing in the fluid phase. The bridge-mediated transfer rate is found to be a maximum for a collinear geometry. Moreover, a multi-level model of the mediator is necessary for energy migration. Asymptotically limiting rates for arbitrary and collinear geometries are also obtained for one centre purely electric dipolar and the other purely quadrupolar, or both donor and absorber purely quadrupolar. Understanding is gained of radiationless and radiative transfer mechanisms between chiral moieties in a dielectric medium.
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Affiliation(s)
- A. Salam
- Department of Chemistry, Wake Forest University, United States of America
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14
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Gera T, Sebastian KL. Exact Results for the Tavis-Cummings and Hückel Hamiltonians with Diagonal Disorder. J Phys Chem A 2022; 126:5449-5457. [PMID: 35921244 DOI: 10.1021/acs.jpca.2c02359] [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
We present an exact method to calculate the electronic states of one electron Hamiltonians with diagonal disorder. We show that in cases where the disorder has a Cauchy distribution, the disorder averaged one particle Green's function can be calculated directly, using a deterministic, complex (non-Hermitian) Hamiltonian. For this we use the supersymmetric method which has already been used in problems of solid state physics. Using the method we find exact solution for the case of N molecules with site disorder, confined to a microcavity, for any value of N. Our analysis shows that the width of the polaritonic states as a function of N depends on the nature of disorder, and hence it can be used to probe the way molecular energy levels are distributed. We also show how one can find exact results for Hückel type Hamiltonians with on-site Cauchy disorder and demonstrate its use.
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Affiliation(s)
- Tarun Gera
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - K L Sebastian
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
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15
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Riso RR, Haugland TS, Ronca E, Koch H. On the characteristic features of ionization in QED environments. J Chem Phys 2022; 156:234103. [PMID: 35732519 DOI: 10.1063/5.0091119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ionization of molecular systems is important in many chemical processes, such as electron transfer and hot electron injection. Strong coupling between molecules and quantized fields (e.g., inside optical cavities) represents a new promising way to modify molecular properties in a non-invasive way. Recently, strong light-matter coupling has shown the potential to significantly improve the rates of hot electron driven processes, for instance, in water splitting. In this paper, we demonstrate that inside an optical cavity, the residual interaction between an outgoing free electron and the vacuum field is significant. We further show that since the quantized field is also interacting with the ionized molecule, the free electron and the molecular system are correlated. We develop a theoretical framework to account for the field induced correlation and show that the interaction between the free electron and the field, free electron-field interaction, has sizable effects on the ionization potential of typical organic molecules.
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Affiliation(s)
- Rosario R Riso
- Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Tor S Haugland
- Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Enrico Ronca
- Istituto per i Processi Chimico Fisici del CNR (IPCF-CNR), Via G.Moruzzi, 1, 56124 Pisa, Italy
| | - Henrik Koch
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
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16
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Gera T, Sebastian KL. Effects of disorder on polaritonic and dark states in a cavity using the disordered Tavis-Cummings model. J Chem Phys 2022; 156:194304. [PMID: 35597631 DOI: 10.1063/5.0086027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We consider molecules confined to a microcavity of dimensions such that an excitation of the molecule is nearly resonant with a cavity mode. The molecular excitation energies are assumed to be Gaussianly distributed with mean ϵa and variance σ. We find an asymptotically exact solution for large number density N. Conditions for the existence of the polaritonic states and expressions for their energies are obtained. Polaritonic states are found to be quite stable against disorder. Our results are verified by comparison with simulations. When ϵa is equal to energy of the cavity state ϵc, the Rabi splitting is found to increase by 2σ2N|Ṽ|, where Ṽ is the coupling of a molecular excitation to the cavity state. An analytic expression is found for the disorder-induced width of the polaritonic peak. Results for various densities of states and the absorption spectrum are presented. The dark states turn "gray" in the presence of disorder with their contribution to the absorption increasing with σ. Lifetimes of the cavity and molecular states are found to be important, and for sufficiently large Rabi splitting, the width of the polaritonic peaks is dominated by them. We also give analytical results for the case where the molecular levels follow a uniform distribution. We conclude that the study of the width of the polaritonic peaks as a function of the Rabi splitting can give information on the distribution of molecular energy levels. Finally, the effects of (a) orientational disorder and (b) spatial variation on the cavity field are presented.
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Affiliation(s)
- Tarun Gera
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - K L Sebastian
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
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17
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Campos-Gonzalez-Angulo JA, Yuen-Zhou J. Generalization of the Tavis-Cummings model for multi-level anharmonic systems: Insights on the second excitation manifold. J Chem Phys 2022; 156:194308. [PMID: 35597658 DOI: 10.1063/5.0087234] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Confined electromagnetic modes strongly couple to collective excitations in ensembles of quantum emitters, producing light-matter hybrid states known as polaritons. Under such conditions, the discrete multilevel spectrum of molecular systems offers an appealing playground for exploring multiphoton processes. This work contrasts predictions from the Tavis-Cummings model in which the material is a collection of two-level systems, with the implications of considering additional energy levels with harmonic and anharmonic structures. We discuss the exact eigenspectrum, up to the second excitation manifold, of an arbitrary number N of oscillators collectively coupled to a single cavity mode in the rotating-wave approximation. Elaborating on our group-theoretic approach [New J. Phys. 23, 063081 (2021)], we simplify the brute-force diagonalization of N2 × N2 Hamiltonians to the eigendecomposition of, at most, 4 × 4 matrices for arbitrary N. We thoroughly discuss the eigenstates and the consequences of weak and strong anharmonicities. Furthermore, we find resonant conditions between bipolaritons and anharmonic transitions where two-photon absorption can be enhanced. Finally, we conclude that energy shifts in the polaritonic states induced by anharmonicities become negligible for large N. Thus, calculations with a single or few quantum emitters qualitatively fail to represent the nonlinear optical response of the collective strong coupling regime. Our work highlights the rich physics of multilevel anharmonic systems coupled to cavities absent in standard models of quantum optics. We also provide concise tabulated expressions for eigenfrequencies and transition amplitudes, which should serve as a reference for future spectroscopic studies of molecular polaritons.
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Affiliation(s)
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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18
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Multimode polariton effects on molecular energy transport and spectral fluctuations. Commun Chem 2022; 5:48. [PMID: 36697846 PMCID: PMC9814737 DOI: 10.1038/s42004-022-00660-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 03/04/2022] [Indexed: 01/28/2023] Open
Abstract
Despite the potential paradigm breaking capability of microcavities to control chemical processes, the extent to which photonic devices change properties of molecular materials is still unclear, in part due to challenges in modeling hybrid light-matter excitations delocalized over many length scales. We overcome these challenges for a photonic wire under strong coupling with a molecular ensemble. Our simulations provide a detailed picture of the effect of photonic wires on spectral and transport properties of a disordered molecular material. We find stronger changes to the probed molecular observables when the cavity is redshifted relative to the molecules and energetic disorder is weak. These trends are expected to hold also in higher-dimensional cavities, but are not captured with theories that only include a single cavity-mode. Therefore, our results raise important issues for future experiments and model building focused on unraveling new ways to manipulate chemistry with optical cavities.
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19
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Abstract
Coupling between molecules and vacuum photon fields inside an optical cavity has proven to be an effective way to engineer molecular properties, in particular reactivity. To ease the rationalization of cavity induced effects we introduce an ab initio method leading to the first fully consistent molecular orbital theory for quantum electrodynamics environments. Our framework is non-perturbative and explains modifications of the electronic structure due to the interaction with the photon field. In this work, we show that the newly developed orbital theory can be used to predict cavity induced modifications of molecular reactivity and pinpoint classes of systems with significant cavity effects. We also investigate electronic cavity-induced modifications of reaction mechanisms in vibrational strong coupling regimes. Theoretical description of light-matter coupling in the strong-coupling regime is challenging. Here the authors introduce a fully consistent ab-initio method of molecular orbital theory applicable to material systems in quantum electrodynamics environments.
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20
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Du M, Yuen-Zhou J. Catalysis by Dark States in Vibropolaritonic Chemistry. PHYSICAL REVIEW LETTERS 2022; 128:096001. [PMID: 35302824 DOI: 10.1103/physrevlett.128.096001] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 12/21/2021] [Accepted: 02/01/2022] [Indexed: 05/25/2023]
Abstract
Collective strong coupling between a disordered ensemble of N localized molecular vibrations and a resonant optical cavity mode gives rise to two polariton and N-1≫2 dark modes. Thus, experimental changes in thermally activated reaction kinetics due to polariton formation appear entropically unlikely and remain a puzzle. Here we show that the overlooked dark modes, while parked at the same energy as bare molecular vibrations, are robustly delocalized across ∼2-3 molecules, yielding enhanced channels of vibrational cooling, concomitantly catalyzing a chemical reaction. As an illustration, we theoretically show an ≈50% increase in an electron transfer rate due to enhanced product stabilization. The reported effects can arise when the homogeneous linewidths of the dark modes are smaller than their energy spacings.
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Affiliation(s)
- Matthew Du
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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21
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Vurgaftman I, Simpkins BS, Dunkelberger AD, Owrutsky JC. Comparative analysis of polaritons in bulk, dielectric slabs, and planar cavities with implications for cavity-modified reactivity. J Chem Phys 2022; 156:034110. [DOI: 10.1063/5.0078148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Igor Vurgaftman
- Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Blake S. Simpkins
- Naval Research Laboratory, Washington, District of Columbia 20375, USA
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22
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Fassioli F, Park KH, Bard SE, Scholes GD. Femtosecond Photophysics of Molecular Polaritons. J Phys Chem Lett 2021; 12:11444-11459. [PMID: 34792371 DOI: 10.1021/acs.jpclett.1c03183] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Molecular polaritons are hybrid states of photonic and molecular character that form when molecules strongly interact with light. Strong coupling tunes energy levels and, importantly, can modify molecular properties (e.g., photoreaction rates), opening an avenue for novel polariton chemistry. In this Perspective, we focus on the collective aspects of strongly coupled molecular systems and how this pertains to the dynamical response of such systems, which, though of key importance for attaining modified function under polariton formation, is still not well-understood. We discuss how the ultrafast time and spectral resolution make pump-probe spectroscopy an ideal tool to reveal the energy-transfer pathways from polariton states to other molecular states of functional interest. Finally, we illustrate how analyzing the free (rather than electronic) energy structure in molecular polariton systems may provide new clues into how energy flows and thus how strong coupling may be exploited.
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Affiliation(s)
- Francesca Fassioli
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- SISSA - Scuola Internazionale Superiore di Studi Avanzati, Trieste 34136, Italy
| | - Kyu Hyung Park
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Sarah E Bard
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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23
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Rolczynski BS, Díaz SA, Kim YC, Medintz IL, Cunningham PD, Melinger JS. Understanding Disorder, Vibronic Structure, and Delocalization in Electronically Coupled Dimers on DNA Duplexes. J Phys Chem A 2021; 125:9632-9644. [PMID: 34709821 DOI: 10.1021/acs.jpca.1c07205] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Structural DNA nanotechnology is a promising approach to create chromophore networks with modular structures and Hamiltonians to control the material's functions. The functional behaviors of these systems depend on the interactions of the chromophores' vibronic states, as well as interactions with their environment. To optimize their functions, it is necessary to characterize the chromophore network's structural and energetic properties, including the electronic delocalization in some cases. In this study, parameters of interest are deduced in DNA-scaffolded Cyanine 3 and Cyanine 5 dimers. The methods include steady-state optical measurements, physical modeling, and a genetic algorithm approach. The parameters include the chromophore network's vibronic Hamiltonian, molecular positions, transition dipole orientations, and environmentally induced energy broadening. Additionally, the study uses temperature-dependent optical measurements to characterize the spectral broadening further. These combined results reveal the quantum mechanical delocalization, which is important for functions like coherent energy transport and quantum information applications.
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Affiliation(s)
- Brian S Rolczynski
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Sebastián A Díaz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Young C Kim
- Materials Science and Technology Division, Code 6300, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Igor L Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Paul D Cunningham
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Joseph S Melinger
- Electronics Science and Technology Division, Code 6800, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
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24
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Baraclough M, Hooper IR, Barnes WL. Metamaterial Analogues of Strongly Coupled Molecular Ensembles. ACS PHOTONICS 2021; 8:2997-3003. [PMID: 34692899 PMCID: PMC8532157 DOI: 10.1021/acsphotonics.1c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Indexed: 06/13/2023]
Abstract
The formation of polariton modes due to the strong coupling of light and matter has led to exciting developments in physics, chemistry, and materials science. The potential to modify the properties of molecular materials by strongly coupling molecules to a confined light field is so far-reaching and so attractive that a new field known as "polaritonic chemistry" is now emerging. However, the molecular scale of the materials involved makes probing strong coupling at the individual resonator level extremely challenging. Here, we offer a complementary approach based upon metamaterials, an approach that enables us to use cm-scale structures, thereby opening a new way to explore strong coupling phenomena. As proof-of-principle, we show that metamolecules placed inside a radio frequency cavity may exhibit strong coupling and show that near-field radio frequency techniques allow us, for the first time, to probe the response of individual metamolecules under strong coupling conditions.
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25
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DelPo CA, Khan SUZ, Park KH, Kudisch B, Rand BP, Scholes GD. Polariton Decay in Donor-Acceptor Cavity Systems. J Phys Chem Lett 2021; 12:9774-9782. [PMID: 34595929 DOI: 10.1021/acs.jpclett.1c02644] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Enhanced delocalization is beneficial for absorbing molecules in organic solar cells, and in particular bilayer devices, where excitons face small diffusion lengths as a barrier to reaching the charge-generating donor-acceptor interface. As hybrid light-matter states, polaritons offer exceptional delocalization which could be used to improve the efficiency of bilayer organic photovoltaics. Polariton delocalization can aid in delivering excitons to the donor-acceptor interface, but the subsequent charge transfer event must compete with the fast decay of the polariton. To evaluate the viability of polaritons as tools to improve bilayer organic solar cells, we studied the decay of the lower polariton in three cavity systems: a donor only, a donor-acceptor bilayer, and a donor-acceptor blend. Using several spectroscopic techniques, we identified an additional decay pathway through charge transfer for the polariton in the bilayer cavity, demonstrating charge transfer from the polariton is fast enough to outcompete the decay to the ground state.
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Affiliation(s)
- Courtney A DelPo
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Saeed-Uz-Zaman Khan
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Kyu Hyung Park
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Bryan Kudisch
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Barry P Rand
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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26
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Turkin A, Malý P, Lambert C. Fluorescence band exchange narrowing in a series of squaraine oligomers: energetic vs. structural disorder. Phys Chem Chem Phys 2021; 23:18393-18403. [PMID: 34612380 DOI: 10.1039/d1cp02136b] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The influence of oligosquaraine chain length on the energies and shape of absorption and emission bands and the exciton coherence length is studied in CHCl3 where the oligomers adopt a random coil structure. From the observed fluorescence band narrowing an effective coherence length of Ncoh = 2.5 was estimated for the nonamer. Applying a theoretical Frenkel exciton model the absorption and emission spectra were simulated which confirmed the experimental results. From the relative amplitude of the 00 peak to the vibronic shoulder the coherence length was estimated which yields a somewhat higher saturation value of Ncoh≈ 3 for the nonamer, which is in very good agreement with the theoretical amplitude ratio. The coherence length is much smaller than the geometrical length because the electronic delocalisation is reduced by structural disorder. Taking into account the energetic (diagonal) and structural (off-diagonal) disorder we observed a different influence on the absorption and fluorescence spectra. For the emission spectra, exciton delocalisation leads to a narrowing of the band caused by averaging over energetic disorder, but for the absorption band the spectra are broadened by excitonic splitting and structural disorder.
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Affiliation(s)
- Arthur Turkin
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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27
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Prodhan S, Giannini S, Wang L, Beljonne D. Long-Range Interactions Boost Singlet Exciton Diffusion in Nanofibers of π-Extended Polymer Chains. J Phys Chem Lett 2021; 12:8188-8193. [PMID: 34415752 DOI: 10.1021/acs.jpclett.1c02275] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Raising the distance covered by singlet excitons during their lifetimes to values maximizing light absorption (a few hundred nm) would solve the exciton diffusion bottleneck issue and lift the constraint for fine (∼10 nm) phase segregation in bulk heterojunction organic solar cells. In that context, the recent report of highly ordered conjugated polymer nanofibers featuring singlet exciton diffusion length, LD, in excess of 300 nm is both appealing and intriguing [Jin, X.; et al. Science 2018, 360 (6391), 897-900]. Here, on the basis of nonadiabatic molecular dynamics simulations, we demonstrate that singlet exciton diffusion in poly(3-hexylthiophene) (P3HT) fibers is highly sensitive to the interplay between delocalization along the polymer chains and long-range interactions along the stacks. Remarkably, the diffusion coefficient is predicted to rocket by 3 orders of magnitude when going beyond nearest-neighbor intermolecular interactions in fibers of extended (30-mer) polymer chains and to be resilient to interchain energetic and positional disorders.
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Affiliation(s)
- Suryoday Prodhan
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium
| | - Samuele Giannini
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium
| | - Linjun Wang
- Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons 7000, Belgium
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28
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Scholes GD. Emergence of Collective Coherent States from Strong-Light Coupling of Disordered Systems. J Phys Chem A 2021; 125:6739-6750. [PMID: 34324322 DOI: 10.1021/acs.jpca.1c05400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An empirical framework for studying the way vacuum fluctuations in a Fabry-Perot cavity produce collective light-matter hybrid states (polariton states) is reported. The reason that the Tavis-Cummings model, where a single mode of the radiation field couples to all the molecules, succeeds is discussed in terms of the strong phase correlation of the vacuum fluctuations in the cavity, which produces a single effective cavity mode (ECM). The model is used to study the onset of the collective state, or "superradiant phase", for ensembles of molecules with significant disorder in their transition energies, as a function of cavity strength factor, from low Q cavities to high Q cavities. A key result is the quantification of the coherence of the ensemble of the lowest energy eigenstate. This is assessed, primarily, using an entropy distance measure. The statistical model provides a physical intuition for the formation of coherence of polariton states when the collective coupling is strong enough that they dominate over the tail of the dark-state density-of-states.
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Affiliation(s)
- Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States
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