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Green D, Bressan G, Heisler IA, Meech SR, Jones GA. Vibrational coherences in half-broadband 2D electronic spectroscopy: Spectral filtering to identify excited state displacements. J Chem Phys 2024; 160:234104. [PMID: 38884412 DOI: 10.1063/5.0214023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 06/03/2024] [Indexed: 06/18/2024] Open
Abstract
Vibrational coherences in ultrafast pump-probe (PP) and 2D electronic spectroscopy (2DES) provide insights into the excited state dynamics of molecules. Femtosecond coherence spectra and 2D beat maps yield information about displacements of excited state surfaces for key vibrational modes. Half-broadband 2DES uses a PP configuration with a white light continuum probe to extend the detection range and resolve vibrational coherences in the excited state absorption (ESA). However, the interpretation of these spectra is difficult as they are strongly dependent on the spectrum of the pump laser and the relative displacement of the excited states along the vibrational coordinates. We demonstrate the impact of these convoluting factors for a model based upon cresyl violet. A careful consideration of the position of the pump spectrum can be a powerful tool in resolving the ESA coherences to gain insights into excited state displacements. This paper also highlights the need for caution in considering the spectral window of the pulse when interpreting these spectra.
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Affiliation(s)
- Dale Green
- Physics, Faculty of Science, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Giovanni Bressan
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Ismael A Heisler
- Instituto de Física, Universidade Federal do Rio Grande do Sul, 91509-900 Porto Alegre, RS, Brazil
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Garth A Jones
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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2
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Rode AJ, Arpin PC, Turner DB. Theoretical model of femtosecond coherence spectroscopy of vibronic excitons in molecular aggregates. J Chem Phys 2024; 160:164101. [PMID: 38647298 DOI: 10.1063/5.0200570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
When used as pump pulses in transient absorption spectroscopy measurements, femtosecond laser pulses can produce oscillatory signals known as quantum beats. The quantum beats arise from coherent superpositions of the states of the sample and are best studied in the Fourier domain using Femtosecond Coherence Spectroscopy (FCS), which consists of one-dimensional amplitude and phase plots of a specified oscillation frequency as a function of the detection frequency. Prior works have shown ubiquitous amplitude nodes and π phase shifts in FCS from excited-state vibrational wavepackets in monomer samples. However, the FCS arising from vibronic-exciton states in molecular aggregates have not been studied theoretically. Here, we use a model of vibronic-exciton states in molecular dimers based on displaced harmonic oscillators to simulate FCS for dimers in two important cases. Simulations reveal distinct spectral signatures of excited-state vibronic-exciton coherences in molecular dimers that may be used to distinguish them from monomer vibrational coherences. A salient result is that, for certain relative orientations of the transition dipoles, the key resonance condition between the electronic coupling and the frequency of the vibrational mode may yield strong enhancement of the quantum-beat amplitude and, perhaps, also cause a significant decrease of the oscillation frequency to a value far lower than the vibrational frequency. Future studies using these results will lead to new insights into the excited-state coherences generated in photosynthetic pigment-protein complexes.
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Affiliation(s)
- Alexander J Rode
- Micron School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, USA
| | - Paul C Arpin
- Department of Physics, California State University, Chico, Chico, California 95929, USA
| | - Daniel B Turner
- Micron School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, USA
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3
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Petropoulos V, Rukin PS, Quintela F, Russo M, Moretti L, Moore A, Moore T, Gust D, Prezzi D, Scholes GD, Molinari E, Cerullo G, Troiani F, Rozzi CA, Maiuri M. Vibronic Coupling Drives the Ultrafast Internal Conversion in a Functionalized Free-Base Porphyrin. J Phys Chem Lett 2024; 15:4461-4467. [PMID: 38630018 DOI: 10.1021/acs.jpclett.4c00372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Internal conversion (IC) is a common radiationless transition in polyatomic molecules. Theory predicts that molecular vibrations assist IC between excited states, and ultrafast experiments can provide insight into their structure-function relationship. Here we elucidate the dynamics of the vibrational modes driving the IC process within the Q band of a functionalized porphyrin molecule. Through a combination of ultrafast multidimensional spectroscopies and theoretical modeling, we observe a 60 fs Qy-Qx IC and demonstrate that it is driven by the interplay among multiple high-frequency modes. Notably, we identify 1510 cm-1 as the leading tuning mode that brings the porphyrin to an optimal geometry for energy surface crossing. By employing coherent wave packet analysis, we highlight a set of short-lived vibrations (1200-1400 cm-1), promoting the IC within ≈60 fs. Furthermore, we identify one coupling mode (1350 cm-1) that is responsible for vibronic mixing within the Q states. Our findings indicate that porphyrin-core functionalization modulates IC effectively, offering new opportunities in photocatalysis and optoelectronics.
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Affiliation(s)
- Vasilis Petropoulos
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Pavel S Rukin
- CNR - Istituto Nanoscienze, Via Campi 213A, I-41125 Modena, Italy
| | - Frank Quintela
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 213A, I-41125 Modena, Italy
| | - Mattia Russo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Luca Moretti
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Ana Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Thomas Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Deborah Prezzi
- CNR - Istituto Nanoscienze, Via Campi 213A, I-41125 Modena, Italy
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08540, United States
| | - Elisa Molinari
- CNR - Istituto Nanoscienze, Via Campi 213A, I-41125 Modena, Italy
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 213A, I-41125 Modena, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Filippo Troiani
- CNR - Istituto Nanoscienze, Via Campi 213A, I-41125 Modena, Italy
| | - Carlo A Rozzi
- CNR - Istituto Nanoscienze, Via Campi 213A, I-41125 Modena, Italy
| | - Margherita Maiuri
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
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4
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Troiani F. Vibrational response functions for multidimensional electronic spectroscopy in nonadiabatic models. J Chem Phys 2023; 158:054110. [PMID: 36754824 DOI: 10.1063/5.0129073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The interplay of nuclear and electronic dynamics characterizes the multidimensional electronic spectra of various molecular and solid-state systems. Theoretically, the observable effect of such interplay can be accounted for by response functions. Here, we report analytical expressions for the response functions corresponding to a class of model systems. These are characterized by coupling between the diabatic electronic states and the vibrational degrees of freedom, resulting in linear displacements of the corresponding harmonic oscillators, and by nonadiabatic couplings between pairs of diabatic states. In order to derive the linear response functions, we first perform the Dyson expansion of the relevant propagators with respect to the nonadiabatic component of the Hamiltonian, then derive and expand with respect to the displacements the propagators at given interaction times, and finally provide analytical expressions for the time integrals that lead to the different contributions to the linear response function. The approach is then applied to the derivation of third-order response functions describing different physical processes: ground state bleaching, stimulated emission, excited state absorption, and double quantum coherence. Comparisons between the results obtained up to sixth order in the Dyson expansion and independent numerical calculation of the response functions provide evidence of the series convergence in a few representative cases.
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Affiliation(s)
- Filippo Troiani
- Centro S3, CNR-Istituto di Nanoscienze, I-41125 Modena, Italy
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5
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Gelin MF, Chen L, Domcke W. Equation-of-Motion Methods for the Calculation of Femtosecond Time-Resolved 4-Wave-Mixing and N-Wave-Mixing Signals. Chem Rev 2022; 122:17339-17396. [PMID: 36278801 DOI: 10.1021/acs.chemrev.2c00329] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Femtosecond nonlinear spectroscopy is the main tool for the time-resolved detection of photophysical and photochemical processes. Since most systems of chemical interest are rather complex, theoretical support is indispensable for the extraction of the intrinsic system dynamics from the detected spectroscopic responses. There exist two alternative theoretical formalisms for the calculation of spectroscopic signals, the nonlinear response-function (NRF) approach and the spectroscopic equation-of-motion (EOM) approach. In the NRF formalism, the system-field interaction is assumed to be sufficiently weak and is treated in lowest-order perturbation theory for each laser pulse interacting with the sample. The conceptual alternative to the NRF method is the extraction of the spectroscopic signals from the solutions of quantum mechanical, semiclassical, or quasiclassical EOMs which govern the time evolution of the material system interacting with the radiation field of the laser pulses. The NRF formalism and its applications to a broad range of material systems and spectroscopic signals have been comprehensively reviewed in the literature. This article provides a detailed review of the suite of EOM methods, including applications to 4-wave-mixing and N-wave-mixing signals detected with weak or strong fields. Under certain circumstances, the spectroscopic EOM methods may be more efficient than the NRF method for the computation of various nonlinear spectroscopic signals.
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Affiliation(s)
- Maxim F Gelin
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Lipeng Chen
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany
| | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, D-85747 Garching,Germany
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Quintela Rodriguez FE, Troiani F. Vibrational response functions for multidimensional electronic spectroscopy in the adiabatic regime: A coherent-state approach. J Chem Phys 2022; 157:034107. [DOI: 10.1063/5.0094512] [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
Multi-dimensional spectroscopy represents a particularly insightful tool for investigating the interplay of nuclear and electronic dynamics, which plays an important role in a number of photophysical processes and photochemical reactions. Here, we present a coherent state representation of the vibronic dynamics and of the resulting response functions for the widely used linearly displaced harmonic oscillator model. Analytical expressions are initially derived for the case of third-order response functions in an N-level system, with ground state initialization of the oscillator (zero-temperature limit). The results are then generalized to the case of Mth order response functions, with arbitrary M. The formal derivation is translated into a simple recipe, whereby the explicit analytical expressions of the response functions can be derived directly from the Feynman diagrams. We further generalize to the whole set of initial coherent states, which form an overcomplete basis. This allows one, in principle, to derive the dependence of the response functions on arbitrary initial states of the vibrational modes and is here applied to the case of thermal states. Finally, a non-Hermitian Hamiltonian approach is used to include in the above expressions the effect of vibrational relaxation.
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Affiliation(s)
| | - Filippo Troiani
- Centro S3, CNR-Istituto di Nanoscienze, I-41125 Modena, Italy
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7
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Lee SN, Ahn J, Joo T. Coherent Vibrational Spectrum via Time-Resolved Fluorescence for Molecular Dynamics and Identification of Emitting Species-Application to Excited-State Intramolecular Proton Transfer. J Phys Chem A 2022; 126:4962-4968. [PMID: 35856811 DOI: 10.1021/acs.jpca.2c03263] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Time-resolved fluorescence (TF) with high-enough resolution enables recording of a coherent vibrational spectrum (CVS). Because a CVS attained via TF (CVSF) is descended from the frequency modulation of the fluorescence spectrum, it gives the vibrational spectrum of the emitting state. Therefore, CVSF can be a powerful tool for the identification of an emitting state along with the investigation of molecular dynamics in excited states. Herein, we report CVSF of a Schiff base salicylaldehyde azine (SAA) that has two possible excited-state intramolecular proton transfer (ESIPT) sites. The ESIPT time of SAA in dichloromethane is determined to be 22 fs. Quantitative agreement between the experimental CVSF and calculated CVSF of the mono-keto isomer demonstrates that ESIPT indeed occurs in SAA only on one side. More importantly, we show that a CVSF can be utilized to identify an emitting species and its state with the help of quantum chemical calculations. Implications of the CVSF obtained by assuming impulsive excitation of vibrations are discussed in terms of the molecular mechanism of ESIPT and the generation of nuclear wave packets in the product state.
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Affiliation(s)
- Seung Noh Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Jungsoo Ahn
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Taiha Joo
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
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Barclay M, Huff JS, Pensack RD, Davis PH, Knowlton WB, Yurke B, Dean JC, Arpin PC, Turner DB. Characterizing Mode Anharmonicity and Huang-Rhys Factors Using Models of Femtosecond Coherence Spectra. J Phys Chem Lett 2022; 13:5413-5423. [PMID: 35679146 PMCID: PMC9234982 DOI: 10.1021/acs.jpclett.1c04162] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
Femtosecond laser pulses readily produce coherent quantum beats in transient-absorption spectra. These oscillatory signals often arise from molecular vibrations and therefore may contain information about the excited-state potential energy surface near the Franck-Condon region. Here, by fitting the measured spectra of two laser dyes to microscopic models of femtosecond coherence spectra (FCS) arising from molecular vibrations, we classify coherent quantum-beat signals as fundamentals or overtones and quantify their Huang-Rhys factors and anharmonicity values. We discuss the extracted Huang-Rhys factors in the context of quantum-chemical computations. This work solidifies the use of FCS for analysis of coherent quantum beats arising from molecular vibrations, which will aid studies of molecular aggregates and photosynthetic proteins.
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Affiliation(s)
- Matthew
S. Barclay
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
| | - Jonathan S. Huff
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
| | - Ryan D. Pensack
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
| | - Paul H. Davis
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
| | - William B. Knowlton
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
- Department
of Electrical & Computer Engineering, Boise State University, Boise, Idaho 83725, United States
| | - Bernard Yurke
- Micron
School for Materials Science and Engineering, Boise State University, Boise, Idaho 83725, United States
- Department
of Electrical & Computer Engineering, Boise State University, Boise, Idaho 83725, United States
| | - Jacob C. Dean
- Department
of Physical Science, Southern Utah University, Cedar City, Utah 84720, United States
| | - 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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9
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Dhamija S, Bhutani G, Jayachandran A, De AK. A Revisit on Impulsive Stimulated Raman Spectroscopy: Importance of Spectral Dispersion of Chirped Broadband Probe. J Phys Chem A 2022; 126:1019-1032. [PMID: 35142494 DOI: 10.1021/acs.jpca.1c10566] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The usefulness of a chirped broadband probe and spectral dispersion to obtain Raman spectra under nonresonant/resonant impulsive excitation is revisited. A general methodology is presented that inherently takes care of phasing the time-domain low-frequency oscillations without probe pulse compression and retrieves the absolute phase of the oscillations. As test beds, neat solvents (CCl4, CHCl3, and CH2Cl2) are used. Observation of periodic intensity modulation along detection wavelengths for particular modes is explained using a simple electric field interaction picture. This method is extended to diatomic molecule (iodine) and polyatomic molecules (Nile blue and methylene blue) to assign vibrational frequencies in ground/excited electronic state that are supported by density functional theory calculations. A comparison between frequency-domain and time-domain counterparts, i.e., stimulated Raman scattering and impulsive stimulated Raman scattering using degenerate pump-probe pairs is presented, and most importantly, it is shown how impulsive stimulated Raman scattering using chirped broadband probe retains unique advantages offered by both.
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Affiliation(s)
- Shaina Dhamija
- Condensed Phase Dynamics Group, Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Garima Bhutani
- Condensed Phase Dynamics Group, Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Ajay Jayachandran
- Condensed Phase Dynamics Group, Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Arijit K De
- Condensed Phase Dynamics Group, Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
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Bressan G, Jirasek M, Roy P, Anderson HL, Meech SR, Heisler IA. Population and Coherence Dynamics in Large Conjugated Porphyrin Nanorings. Chem Sci 2022; 13:9624-9636. [PMID: 36091893 PMCID: PMC9400675 DOI: 10.1039/d2sc01971j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022] Open
Abstract
In photosynthesis, nature exploits the distinctive electronic properties of chromophores arranged in supramolecular rings for efficient light harvesting. Among synthetic supramolecular cyclic structures, porphyrin nanorings have attracted considerable attention as they have a resemblance to naturally occurring light-harvesting structures but offer the ability to control ring size and the level of disorder. Here, broadband femtosecond transient absorption spectroscopy, with pump pulses in resonance with either the high or the low energy sides of the inhomogeneously broadened absorption spectrum, is used to study the population dynamics and ground and excited state vibrational coherence in large porphyrin nanorings. A series of fully conjugated, alkyne bridged, nanorings constituted of between ten and forty porphyrin units is studied. Pump-wavelength dependent fast spectral evolution is found. A fast rise or decay of the stimulated emission is found when large porphyrin nanorings are excited on, respectively, the high or low energy side of the absorption spectrum. Such dynamics are consistent with the hypothesis of a variation in transition dipole moment across the inhomogeneously broadened ground state ensemble. The observed dynamics indicate the interplay of nanoring conformation and oscillator strength. Oscillatory dynamics on the sub-ps time domain are observed in both pumping conditions. A combined analysis of the excitation wavelength-dependent transient spectra along with the amplitude and phase evolution of the oscillations allows assignment to vibrational wavepackets evolving on either ground or excited states electronic potential energy surfaces. Even though porphyrin nanorings support highly delocalized electronic wavefunctions, with coherence length spanning tens of chromophores, the measured vibrational coherences remain localised on the monomers. The main contributions to the beatings are assigned to two vibrational modes localised on the porphyrin cores: a Zn–N stretching mode and a skeletal methinic/pyrrolic C–C stretching and in-plane bending mode. Pump wavelength-dependent, ultrafast excited state dynamics arising from inhomogeneous broadening and ground and excited state nuclear wavepackets were observed for a series of Zn porphyrin nanorings made of 10 to 40 repeating units.![]()
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Affiliation(s)
- Giovanni Bressan
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Michael Jirasek
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Palas Roy
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Harry L Anderson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Stephen R Meech
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Ismael A Heisler
- Instituto de Física, Universidade Federal do Rio Grande do Sul Avenida Bento Gonçalves, 9500, CEP 91501-970 Porto Alegre Brazil
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