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Mehmood A, Silfies MC, Durden AS, Allison TK, Levine BG. Simulating ultrafast transient absorption spectra from first principles using a time-dependent configuration interaction probe. J Chem Phys 2024; 161:044107. [PMID: 39041880 DOI: 10.1063/5.0215890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/30/2024] [Indexed: 07/24/2024] Open
Abstract
Transient absorption spectroscopy (TAS) is among the most common ultrafast photochemical experiments, but its interpretation remains challenging. In this work, we present an efficient and robust method for simulating TAS signals from first principles. Excited-state absorption and stimulated emission (SE) signals are computed using time-dependent complete active space configuration interaction (TD-CASCI) simulations, leveraging the robustness of time-domain simulation to minimize electronic structure failure. We demonstrate our approach by simulating the TAS signal of 1'-hydroxy-2'-acetonapthone (HAN) from ab initio multiple spawning nonadiabatic molecular dynamics simulations. Our results are compared to gas-phase TAS data recorded from both jet-cooled (T ∼ 40 K) and hot (∼403 K) molecules via cavity-enhanced TAS (CE-TAS). Decomposition of the computed spectrum allows us to assign a rise in the SE signal to excited-state proton transfer and the ultimate decay of the signal to relaxation through a twisted conical intersection. The total cost of computing the observable signal (∼1700 graphics processing unit hours for ∼4 ns of electron dynamics) was markedly less than that of performing the ab initio multiple spawning calculations used to compute the underlying nonadiabatic dynamics.
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Affiliation(s)
- Arshad Mehmood
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
| | - Myles C Silfies
- Department of Physics, Stony Brook University, Stony Brook, New York 11794, USA
| | - Andrew S Durden
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
| | - Thomas K Allison
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Physics, Stony Brook University, Stony Brook, New York 11794, USA
| | - Benjamin G Levine
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
- Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
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Park SJ, Schwartz BJ. How Ions Break Local Symmetry: Simulations of Polarized Transient Hole Burning for Different Models of the Hydrated Electron in Contact Pairs with Na . J Phys Chem Lett 2023; 14:3014-3022. [PMID: 36943261 DOI: 10.1021/acs.jpclett.3c00220] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The hydrated electron (eaq-) is known via polarized transient hole-burning (pTHB) experiments to have a homogeneously broadened absorption spectrum. Here, we explore via quantum simulation how the pTHB spectroscopy of different eaq- models changes in the presence of electrolytes. The idea is that cation-eaq- pairing can break the local symmetry and, thus, induce persistent inhomogeneity. We find that a "hard" cavity model shows a modest increase in the pTHB recovery time in the presence of salt, while a "soft" cavity model remains homogeneously broadened independent of the salt concentration. We also explore the orientational anisotropy of a fully ab initio density functional theory-based model of the eaq-, which is strongly inhomogeneously broadened without salt and which becomes significantly more inhomogeneously broadened in the presence of salt. The results provide a direct prediction for experiments that can distinguish between different models and, thus, help pin down the hydration structure and dynamics of the eaq-.
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Affiliation(s)
- Sanghyun J Park
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
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Marin TW, Janik I, Bartels DM, Chipman DM. Failure of molecular dynamics to provide appropriate structures for quantum mechanical description of the aqueous chloride ion charge-transfer-to-solvent ultraviolet spectrum. Phys Chem Chem Phys 2021; 23:9109-9120. [PMID: 33885094 DOI: 10.1039/d1cp00930c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The lowest band in the charge-transfer-to-solvent ultraviolet absorption spectrum of aqueous chloride ion is studied by experiment and computation. Interestingly, the experiments indicate that at concentrations up to at least 0.25 M, where calculations indicate ion pairing to be significant, there is no notable effect of ionic strength on the spectrum. The experimental spectra are fitted to aid comparison with computations. Classical molecular dynamic simulations are carried out on dilute aqueous Cl-, Na+, and NaCl, producing radial distribution functions in reasonable agreement with experiment and, for NaCl, clear evidence of ion pairing. Clusters are extracted from the simulations for quantum mechanical excited state calculations. Accurate ab initio coupled-cluster benchmark calculations on a small number of representative clusters are carried out and used to identify and validate an efficient protocol based on time-dependent density functional theory. The latter is used to carry out quantum mechanical calculations on thousands of clusters. The resulting computed spectrum is in excellent agreement with experiment for the peak position, with little influence from ion pairing, but is in qualitative disagreement on the width, being only about half as wide. It is concluded that simulation by classical molecular dynamics fails to provide an adequate variety of structures to explain the experimental CTTS spectrum of aqueous Cl-.
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Affiliation(s)
- Timothy W Marin
- Department of Physical Sciences, Benedictine University, 5700 College Rd, Lisle, IL 60532, USA
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Abstract
A cavity or excluded-volume structure best explains the experimental properties of the aqueous or “hydrated” electron.
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Affiliation(s)
- John M. Herbert
- Department of Chemistry & Biochemistry
- The Ohio State University
- Columbus
- USA
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5
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Zho CC, Farr EP, Glover WJ, Schwartz BJ. Temperature dependence of the hydrated electron’s excited-state relaxation. I. Simulation predictions of resonance Raman and pump-probe transient absorption spectra of cavity and non-cavity models. J Chem Phys 2017; 147:074503. [DOI: 10.1063/1.4985905] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Chen-Chen Zho
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California,
90095-1569, USA
| | - Erik P. Farr
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California,
90095-1569, USA
| | - William J. Glover
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California,
90095-1569, USA
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
- NYU Shanghai, 1555 Century Avenue,
Shanghai 200135, China
| | - Benjamin J. Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California,
90095-1569, USA
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Zho CC, Schwartz BJ. Time-Resolved Photoelectron Spectroscopy of the Hydrated Electron: Comparing Cavity and Noncavity Models to Experiment. J Phys Chem B 2016; 120:12604-12614. [PMID: 27973828 DOI: 10.1021/acs.jpcb.6b07852] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Chen-Chen Zho
- Department of Chemistry and
Biochemistry University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Benjamin J. Schwartz
- Department of Chemistry and
Biochemistry University of California, Los Angeles, Los Angeles, California 90095-1569, United States
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Turi L. Hydration dynamics in water clusters via quantum molecular dynamics simulations. J Chem Phys 2014; 140:204317. [DOI: 10.1063/1.4879517] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Casey JR, Kahros A, Schwartz BJ. To be or not to be in a cavity: the hydrated electron dilemma. J Phys Chem B 2013; 117:14173-82. [PMID: 24160853 DOI: 10.1021/jp407912k] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrated electron-the species that results from the addition of a single excess electron to liquid water-has been the focus of much interest both because of its role in radiation chemistry and other chemical reactions, and because it provides for a deceptively simple system that can serve as a means to confront the predictions of quantum molecular dynamics simulations with experiment. Despite all this interest, there is still considerable debate over the molecular structure of the hydrated electron: does it occupy a cavity, have a significant number of interior water molecules, or have a structure somewhere in between? The reason for all this debate is that different computer simulations have produced each of these different structures, yet the predicted properties for these different structures are still in reasonable agreement with experiment. In this Feature Article, we explore the reasons underlying why different structures are produced when different pseudopotentials are used in quantum simulations of the hydrated electron. We also show that essentially all the different models for the hydrated electron, including those from fully ab initio calculations, have relatively little direct overlap of the electron's wave function with the nearby water molecules. Thus, a non-cavity hydrated electron is better thought of as an "inverse plum pudding" model, with interior waters that locally expel the surrounding electron's charge density. Finally, we also explore the agreement between different hydrated electron models and certain key experiments, such as resonance Raman spectroscopy and the temperature dependence and degree of homogeneous broadening of the optical absorption spectrum, in order to distinguish between the different simulated structures. Taken together, we conclude that the hydrated electron likely has a significant number of interior water molecules.
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Affiliation(s)
- Jennifer R Casey
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095-1569, United States
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Doan SC, Schwartz BJ. Nature of Excess Electrons in Polar Fluids: Anion-Solvated Electron Equilibrium and Polarized Hole-Burning in Liquid Acetonitrile. J Phys Chem Lett 2013; 4:1471-1476. [PMID: 26282301 DOI: 10.1021/jz400621m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Stephanie C Doan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
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Turi L, Rossky PJ. Theoretical studies of spectroscopy and dynamics of hydrated electrons. Chem Rev 2012; 112:5641-74. [PMID: 22954423 DOI: 10.1021/cr300144z] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- László Turi
- Department of Physical Chemistry, Eötvös Loránd University, Budapest, Hungary.
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Herbert JM, Jacobson LD. Structure of the aqueous electron: assessment of one-electron pseudopotential models in comparison to experimental data and time-dependent density functional theory. J Phys Chem A 2011; 115:14470-83. [PMID: 22032635 DOI: 10.1021/jp206391d] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The prevailing structural paradigm for the aqueous electron is that of an s-like ground-state wave function that inhabits a quasi-spherical solvent cavity, a viewpoint that is supported by numerous atomistic simulations using various one-electron pseudopotential models. This conceptual picture has recently been challenged, however, on the basis of results obtained from a new electron-water pseudopotential model that predicts a more delocalized wave function and no well-defined solvent cavity. Here, we examine this new model in comparison to two alternative, cavity-forming pseudopotential models. We find that the cavity-forming models are far more consistent with the experimental data for the electron's radius of gyration, optical absorption spectrum, and vertical electron binding energy. Calculations of the absorption spectrum using time-dependent density functional theory are in quantitative or semiquantitative agreement with experiment when the solvent geometries are obtained from the cavity-forming pseudopotential models, but differ markedly from experiment when geometries that do not form a cavity are used.
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Affiliation(s)
- John M Herbert
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43210, United States.
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Herbert JM, Jacobson LD. Nature's most squishy ion: The important role of solvent polarization in the description of the hydrated electron. INT REV PHYS CHEM 2011. [DOI: 10.1080/0144235x.2010.535342] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Jacobson LD, Herbert JM. A one-electron model for the aqueous electron that includes many-body electron-water polarization: Bulk equilibrium structure, vertical electron binding energy, and optical absorption spectrum. J Chem Phys 2010; 133:154506. [DOI: 10.1063/1.3490479] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Affiliation(s)
- Ross E Larsen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA.
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Mones L, Turi L. A new electron-methanol molecule pseudopotential and its application for the solvated electron in methanol. J Chem Phys 2010; 132:154507. [DOI: 10.1063/1.3385798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Bragg AE, Schwartz BJ. The ultrafast charge-transfer-to-solvent dynamics of iodide in tetrahydrofuran. 1. Exploring the roles of solvent and solute electronic structure in condensed-phase charge-transfer reactions. J Phys Chem B 2007; 112:483-94. [PMID: 18085770 DOI: 10.1021/jp076934s] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although they represent the simplest possible charge-transfer reactions, the charge-transfer-to-solvent (CTTS) dynamics of atomic anions exhibit considerable complexity. For example, the CTTS dynamics of iodide in water are very different from those of sodide (Na-) in tetrahydrofuran (THF), leading to the question of the relative importance of the solvent and solute electronic structures in controlling charge-transfer dynamics. In this work, we address this issue by investigating the CTTS spectroscopy and dynamics of I- in THF, allowing us to make detailed comparisons to the previously studied I-/H2O and Na-/THF CTTS systems. Since THF is weakly polar, ion pairing with the counterion can have a substantial impact on the CTTS spectroscopy and dynamics of I- in this solvent. In this study, we have isolated "counterion-free" I- in THF by complexing the Na+ counterion with 18-crown-6 ether. Ultrafast pump-probe experiments reveal that THF-solvated electrons (e-THF) appear 380 +/- 60 fs following the CTTS excitation of "free" I- in THF. The absorption kinetics are identical at all probe wavelengths, indicating that the ejected electrons appear with no significant dynamic solvation but rather with their equilibrium absorption spectrum. After their initial appearance, ejected electrons do not exhibit any additional dynamics on time scales up to approximately 1 ns, indicating that geminate recombination of e-THF with its iodine atom partner does not occur. Competitive electron scavenging measurements demonstrate that the CTTS excited state of I- in THF is quite large and has contact with scavengers that are several nanometers away from the iodide ion. The ejection time and lack of electron solvation observed for I- in THF are similar to what is observed following CTTS excitation of Na- in THF. However, the relatively slow ejection time, the complete lack of dynamic solvation, and the large ejection distance/lack of recombination dynamics are in marked contrast to the CTTS dynamics observed for I- in water, in which fast electron ejection, substantial solvation, and appreciable recombination have been observed. These differences in dynamical behavior can be understood in terms of the presence of preexisting, electropositive cavities in liquid THF that are a natural part of its liquid structure; these cavities provide a mechanism for excited electrons to relocate to places in the liquid that can be nanometers away, explaining the large ejection distance and lack of recombination following the CTTS excitation of I- in THF. We argue that the lack of dynamic solvation observed following CTTS excitation of both I- and Na- in THF is a direct consequence of the fact that little additional relaxation is required once an excited electron nonadiabatically relaxes into one of the preexisting cavities. In contrast, liquid water contains no such cavities, and CTTS excitation of I- in water leads to local electron ejection that involves substantial solvent reorganization.
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Affiliation(s)
- Arthur E Bragg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, USA
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Cavanagh MC, Larsen RE, Schwartz BJ. Watching Na Atoms Solvate into (Na+,e-) Contact Pairs: Untangling the Ultrafast Charge-Transfer-to-Solvent Dynamics of Na- in Tetrahydrofuran (THF). J Phys Chem A 2007; 111:5144-57. [PMID: 17523607 DOI: 10.1021/jp071132i] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
With the large dye molecules employed in typical studies of solvation dynamics, it is often difficult to separate the intramolecular relaxation of the dye from the relaxation associated with dynamic solvation. One way to avoid this difficulty is to study solvation dynamics using an atom as the solvation probe; because atoms have only electronic degrees of freedom, all of the observed spectroscopic dynamics must result from motions of the solvent. In this paper, we use ultrafast transient absorption spectroscopy to investigate the solvation dynamics of newly created sodium atoms that are formed following the charge transfer to solvent (CTTS) ejection of an electron from sodium anions (sodide) in liquid tetrahydrofuran (THF). Because the absorption spectra of the sodide reactant, the sodium atom, and the solvated electron products overlap, we first examined the dynamics of the ejected CTTS electron in the infrared to build a detailed model of the CTTS process that allowed us to subtract the spectroscopic contributions of the sodide bleach and the solvated electron and cleanly reveal the spectroscopy of the solvated atom. We find that the neutral sodium species created following CTTS excitation of sodide initially absorbs near 590 nm, the position of the gas-phase sodium D-line, suggesting that it only weakly interacts with the surrounding solvent. We then see a fast solvation process that causes a red-shift of the sodium atom's spectrum in approximately 230 fs, a time scale that matches well with the results of MD simulations of solvation dynamics in liquid THF. After the fast solvation is complete, the neutral sodium atoms undergo a chemical reaction that takes place in approximately 740 fs, as indicated by the observation of an isosbestic point and the creation of a species with a new spectrum. The spectrum of the species created after the reaction then red-shifts on a approximately 10-ps time scale to become the equilibrium spectrum of the THF-solvated sodium atom, which is known from radiation chemistry experiments to absorb near approximately 900 nm. There has been considerable debate as to whether this 900-nm absorbing species is better thought of as a solvated atom or a sodium cation:solvated electron contact pair, (Na+,e-). The fact that we observe the initially created neutral Na atom undergoing a chemical reaction to ultimately become the 900-nm absorbing species suggests that it is better assigned as (Na+,e-). The approximately 10-ps solvation time we observe for this species is an order of magnitude slower than any other solvation process previously observed in liquid THF, suggesting that this species interacts differently with the solvent than the large molecules that are typically used as solvation probes. Together, all of the results allow us to build the most detailed picture to date of the CTTS process of Na- in THF as well as to directly observe the solvation dynamics associated with single sodium atoms in solution.
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Affiliation(s)
- Molly C Cavanagh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, USA
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Polar and Nonpolar Solvation Dynamics, Ion Diffusion, and Vibrational Relaxation: Role of Biphasic Solvent Response in Chemical Dynamics. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141687.ch4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Bedard-Hearn MJ, Larsen RE, Schwartz BJ. Moving solvated electrons with light: Nonadiabatic mixed quantum/classical molecular dynamics simulations of the relocalization of photoexcited solvated electrons in tetrahydrofuran (THF). J Chem Phys 2006; 125:194509. [PMID: 17129125 DOI: 10.1063/1.2358131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Motivated by recent ultrafast spectroscopic experiments [Martini et al., Science 293, 462 (2001)], which suggest that photoexcited solvated electrons in tetrahydrofuran (THF) can relocalize (that is, return to equilibrium in solvent cavities far from where they started), we performed a series of nonequilibrium, nonadiabatic, mixed quantum/classical molecular dynamics simulations that mimic one-photon excitation of the THF-solvated electron. We find that as photoexcited THF-solvated electrons relax to their ground states either by continuous mixing from the excited state or via nonadiabatic transitions, approximately 30% of them relocalize into cavities that can be over 1 nm away from where they originated, in close agreement with the experiments. A detailed investigation shows that the ability of excited THF-solvated electrons to undergo photoinduced relocalization stems from the existence of preexisting cavity traps that are an intrinsic part of the structure of liquid THF. This explains why solvated electrons can undergo photoinduced relocalization in solvents like THF but not in solvents like water, which lack the preexisting traps necessary to stabilize the excited electron in other places in the fluid. We also find that even when they do not ultimately relocalize, photoexcited solvated electrons in THF temporarily visit other sites in the fluid, explaining why the photoexcitation of THF-solvated electrons is so efficient at promoting recombination with nearby scavengers. Overall, our study shows that the defining characteristic of a liquid that permits the photoassisted relocalization of solvated electrons is the existence of nascent cavities that are attractive to an excess electron; we propose that other such liquids can be found from classical computer simulations or neutron diffraction experiments.
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Affiliation(s)
- Michael J Bedard-Hearn
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, USA
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Larsen RE, Schwartz BJ. Nonadiabatic Molecular Dynamics Simulations of Correlated Electrons in Solution. 2. A Prediction for the Observation of Hydrated Dielectrons with Pump−Probe Spectroscopy. J Phys Chem B 2006; 110:9692-7. [PMID: 16686520 DOI: 10.1021/jp0553232] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The hydrated dielectron is a highly correlated, two-electron, solvent-supported state consisting of two spin-paired electrons confined to a single cavity in liquid water. Although dielectrons have been predicted to exist theoretically and have been used to explain the lack of ionic strength effect in the bimolecular reaction kinetics of hydrated electrons, they have not yet been observed directly. In this paper, we use the extensive nonadiabatic mixed quantum/classical excited-state molecular dynamics simulations from the previous paper to calculate the transient spectroscopy of hydrated dielectrons. Because our simulations use full configuration interaction (CI) to determine the ground and excited state two-electron wave functions at every instant, our nonequilibrium simulations allow us to compute the absorption, stimulated emission (SE), and bleach spectroscopic signals of both singlet and triplet dielectrons following excitation by ultraviolet light. Excited singlet dielectrons are predicted to display strong SE in the mid infrared and a transient absorption in the near-infrared. The near-infrared transient absorption of the singlet dielectron, which occurs near the peak of the (single) hydrated electron's equilibrium absorption, arises because the two electrons tend to separate in the excited state. In contrast, excitation of the hydrated electron gives a bleach signal in this wavelength region. Thus, our calculations suggest a clear pump-probe spectroscopic signature that may be used in the laboratory to distinguish hydrated singlet dielectrons from hydrated electrons: By choosing an excitation energy that is to the blue of the peak of the hydrated electron's absorption spectrum and probing near the maximum of the single electron's absorption, the single electron's transient bleach signal should shrink or even turn into a net absorption as sample conditions are varied to produce more dielectrons.
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Affiliation(s)
- Ross E Larsen
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA
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Shoshana O, Pérez Lustres JL, Ernsting NP, Ruhman S. Mapping CTTS dynamics of Na−in tetrahydrofurane with ultrafast multichannel pump–probe spectroscopy. Phys Chem Chem Phys 2006; 8:2599-609. [PMID: 16738713 DOI: 10.1039/b602933g] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using multichannel femtosecond spectroscopy we have followed Na- charge transfer to solvent (CTTS) dynamics in THF solution. Absorption of the primary photoproducts in the visible, resolved here for the first time, consists of an asymmetric triplet centered at 595 nm, which we assign to a metastable incompletely solvated neutral atomic sodium species. Decay of this feature within approximately 1 ps to a broad and structureless solvated neutral is accompanied by broadening and loss of spectral detail. Kinetic analysis shows that both the spectral structure and the decay of this band are independent of the excitation photon frequency in the range 400-800 nm. With different pump-probe polarizations the anisotropy in transient transmission has been charted and its variation with excitation wavelength surveyed. The anisotropies are assigned to the reactant bleach, indicating that due to solvent-induced symmetry breaking, the CTTS absorption band of Na- is made up of discreet orthogonally polarized sub bands. None of the anisotropy in transient absorption could be associated with the photoproduct triplet band even at the earliest measurable time delays. Along with the documented differences in the spatial distribution of ejected electrons across the tested excitation wavelength range, these results lead us to conclude that photoejection is extremely rapid, and that loss of correlations between the departing electron and its neutral core is faster than our time resolution of approximately 60 fs.
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Affiliation(s)
- O Shoshana
- Department of Physical Chemistry, and the Farkas Center for Light Induced Processes, the Hebrew University, Jerusalem, 91904, Israel.
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Affiliation(s)
- Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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Cavanagh MC, Martini IB, Schwartz BJ. Revisiting the pump–probe polarized transient hole-burning of the hydrated electron: Is its absorption spectrum inhomogeneously broadened? Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.07.109] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Larsen RE, Schwartz BJ. Mixed Quantum/Classical Molecular Dynamics Simulations of the Hydrated Dielectron: The Role of Exchange in Condensed-Phase Structure, Dynamics, and Spectroscopy. J Phys Chem B 2004. [DOI: 10.1021/jp048951c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ross E. Larsen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
| | - Benjamin J. Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569
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28
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Brooksby C, Prezhdo OV, Reid PJ. Molecular dynamics study of the weakly solvent dependent relaxation dynamics following chlorine dioxide photoexcitation. J Chem Phys 2003. [DOI: 10.1063/1.1614203] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Zhan CG, Dixon DA. The Nature and Absolute Hydration Free Energy of the Solvated Electron in Water. J Phys Chem B 2003. [DOI: 10.1021/jp022326v] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chang-Guo Zhan
- William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K1-83, P.O. Box 999, Richland, Washington 99352
| | - David A. Dixon
- William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K1-83, P.O. Box 999, Richland, Washington 99352
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Wang Z, Shoshana O, Hou B, Ruhman S. Solvent Induced Symmetry Breaking and Relaxation Following Charge Transfer to Solvent Excitation of Na- in Tetrahydrofuran. J Phys Chem A 2003. [DOI: 10.1021/jp014331p] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhaohui Wang
- Department of Physical Chemistry, and the Farkas Center for Light Induced Processes, the Hebrew University, Jerusalem 91904, Israel
| | - Ofir Shoshana
- Department of Physical Chemistry, and the Farkas Center for Light Induced Processes, the Hebrew University, Jerusalem 91904, Israel
| | - Bixue Hou
- Department of Physical Chemistry, and the Farkas Center for Light Induced Processes, the Hebrew University, Jerusalem 91904, Israel
| | - Sanford Ruhman
- Department of Physical Chemistry, and the Farkas Center for Light Induced Processes, the Hebrew University, Jerusalem 91904, Israel
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31
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Barthel ER, Martini IB, Keszei E, Schwartz BJ. Solvent effects on the ultrafast dynamics and spectroscopy of the charge-transfer-to-solvent reaction of sodide. J Chem Phys 2003. [DOI: 10.1063/1.1557054] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Bagchi B. 5 Water solvation dynamics in the bulk and in the hydration layer of proteins and self-assemblies. ACTA ACUST UNITED AC 2003. [DOI: 10.1039/b208505b] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Waterland MR, Stockwell D, Kelley AM. Symmetry breaking effects in NO3−: Raman spectra of nitrate salts and ab initio resonance Raman spectra of nitrate–water complexes. J Chem Phys 2001. [DOI: 10.1063/1.1355657] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Martini IB, Barthel ER, Schwartz BJ. Mechanisms of the ultrafast production and recombination of solvated electrons in weakly polar fluids: Comparison of multiphoton ionization and detachment via the charge-transfer-to-solvent transition of Na− in THF. J Chem Phys 2000. [DOI: 10.1063/1.1328071] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Gauduel Y, Gelabert H, Guilloud F. Real-Time Probing of a Three-Electron Bonded Radical: Ultrafast One-Electron Reduction of a Disulfide Biomolecule. J Am Chem Soc 2000. [DOI: 10.1021/ja9933543] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y. Gauduel
- Contribution from the Laboratoire d'Optique Appliquée, CNRS UMR 7631, INSERM U451, Ecole Polytechnique - ENS Techniques Avancées, 91761 Palaiseau Cedex - France
| | - H. Gelabert
- Contribution from the Laboratoire d'Optique Appliquée, CNRS UMR 7631, INSERM U451, Ecole Polytechnique - ENS Techniques Avancées, 91761 Palaiseau Cedex - France
| | - F. Guilloud
- Contribution from the Laboratoire d'Optique Appliquée, CNRS UMR 7631, INSERM U451, Ecole Polytechnique - ENS Techniques Avancées, 91761 Palaiseau Cedex - France
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37
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Gaigeot MP, Borgis D, Staib A. Calculation of the potential of mean force for chloride-argon and sodium-argon pairs in water. J Mol Liq 2000. [DOI: 10.1016/s0167-7322(99)00191-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Assel M, Laenen R, Laubereau A. Femtosecond solvation dynamics of solvated electrons in neat water. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(99)01369-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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39
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Assel M, Laenen R, Laubereau A. Retrapping and solvation dynamics after femtosecond UV excitation of the solvated electron in water. J Chem Phys 1999. [DOI: 10.1063/1.479979] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Bratos S, Leicknam JC. Anisotropy of pump-probe absorption of the hydrated electron: A statistical model. J Chem Phys 1998. [DOI: 10.1063/1.477661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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41
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de Boeij WP, Pshenichnikov MS, Wiersma DA. ULTRAFAST SOLVATION DYNAMICS EXPLORED BY FEMTOSECOND PHOTON ECHO SPECTROSCOPIES. Annu Rev Phys Chem 1998; 49:99-123. [PMID: 15012426 DOI: 10.1146/annurev.physchem.49.1.99] [Citation(s) in RCA: 267] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chemical reaction and optical dynamics in the liquid phase are strongly affected by specific solute-solvent interactions. The dynamical part of this coupling leads to energy fluctuations. The associated energy gap dynamics can be probed by using various nonlinear optical spectroscopies. We discuss various forms of photon echo--time-integrated, time-gated, and heterodyne-detected photon echo--as well as Fourier transform spectral interferometry. It is shown that for solutions of the dye molecule DTTCI, a system-bath correlation function can be acquired that provides a quantitative description of all (non)linear spectroscopic experiments. The deduced correlation function is projected onto the multimode Brownian oscillator model, which allows for a physical interpretation of the multiple-time correlation function and a determination of the spectral density relevant to the solvation process. The following applications of photon echo to condensed phase dynamics are discussed: enhanced vibrational mode suppression, Liouville pathways interference, and dynamical Stokes shift. Recent results of echo-peak shift experiments on the hydrated electron are also presented. The review concludes that photon echo should be useful as a novel tool to explore transition state dynamics.
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Affiliation(s)
- W P de Boeij
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, Groningen, 9747 AG The Netherlands
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44
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Gauduel Y, Sander M, Gelabert H. Electronic dynamics and real-time observations of pre-reactive states in aqueous solutions. J Radioanal Nucl Chem 1998. [DOI: 10.1007/bf02383726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Kummrow A, Emde MF, Baltuška A, Pshenichnikov MS, Wiersma DA. Wave Packet Dynamics in Ultrafast Spectroscopy of the Hydrated Electron. J Phys Chem A 1998. [DOI: 10.1021/jp980254v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Kummrow
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands, and Max-Born-Institute, Rudower Chaussee 6, 12489 Berlin, Germany
| | - M. F. Emde
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands, and Max-Born-Institute, Rudower Chaussee 6, 12489 Berlin, Germany
| | - A. Baltuška
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands, and Max-Born-Institute, Rudower Chaussee 6, 12489 Berlin, Germany
| | - M. S. Pshenichnikov
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands, and Max-Born-Institute, Rudower Chaussee 6, 12489 Berlin, Germany
| | - D. A. Wiersma
- Ultrafast Laser and Spectroscopy Laboratory, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands, and Max-Born-Institute, Rudower Chaussee 6, 12489 Berlin, Germany
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Assel M, Laenen R, Laubereau A. Dynamics of Excited Solvated Electrons in Aqueous Solution Monitored with Femtosecond-Time and Polarization Resolution. J Phys Chem A 1998. [DOI: 10.1021/jp972499y] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Assel
- Physik-Department E 11, Technische Universität München, D-85748 Garching, Germany
| | - R. Laenen
- Physik-Department E 11, Technische Universität München, D-85748 Garching, Germany
| | - A. Laubereau
- Physik-Department E 11, Technische Universität München, D-85748 Garching, Germany
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47
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Borgis D, Bratos S. Theoretical description of the hydrated electron. Shape and spectroscopic properties of the cavity containing the excess electron. J Mol Struct 1997. [DOI: 10.1016/s0022-2860(97)00243-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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48
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Prezhdo OV, Rossky PJ. Evaluation of quantum transition rates from quantum-classical molecular dynamics simulations. J Chem Phys 1997. [DOI: 10.1063/1.474312] [Citation(s) in RCA: 254] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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49
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Turi L, Holpár P, Keszei E. Alternative Mechanisms for Solvation Dynamics of Laser-Induced Electrons in Methanol. J Phys Chem A 1997. [DOI: 10.1021/jp970174b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- L. Turi
- Department of Physical Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
| | - P. Holpár
- Department of Physical Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
| | - E. Keszei
- Department of Physical Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
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Bittner ER, Schwartz BJ, Rossky PJ. Quantum decoherence: a consistent histories treatment of condensed-phase non-adiabatic quantum molecular dynamics. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0166-1280(96)04612-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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