1
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Borrelli W, Mei KJ, Park SJ, Schwartz BJ. Partial Molar Solvation Volume of the Hydrated Electron Simulated Via DFT. J Phys Chem B 2024; 128:2425-2431. [PMID: 38422045 PMCID: PMC10945486 DOI: 10.1021/acs.jpcb.3c05091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 02/03/2024] [Accepted: 02/14/2024] [Indexed: 03/02/2024]
Abstract
Different simulation models of the hydrated electron produce different solvation structures, but it has been challenging to determine which simulated solvation structure, if any, is the most comparable to experiment. In a recent work, Neupane et al. [J. Phys. Chem. B 2023, 127, 5941-5947] showed using Kirkwood-Buff theory that the partial molar volume of the hydrated electron, which is known experimentally, can be readily computed from an integral over the simulated electron-water radial distribution function. This provides a sensitive way to directly compare the hydration structure of different simulation models of the hydrated electron with experiment. Here, we compute the partial molar volume of an ab-initio-simulated hydrated electron model based on density-functional theory (DFT) with a hybrid functional at different simulated system sizes. We find that the partial molar volume of the DFT-simulated hydrated electron is not converged with respect to the system size for simulations with up to 128 waters. We show that even at the largest simulation sizes, the partial molar volume of DFT-simulated hydrated electrons is underestimated by a factor of 2 with respect to experiment, and at the standard 64-water size commonly used in the literature, DFT-based simulations underestimate the experimental solvation volume by a factor of ∼3.5. An extrapolation to larger box sizes does predict the experimental partial molar volume correctly; however, larger system sizes than those explored here are currently intractable without the use of machine-learned potentials. These results bring into question what aspects of the predicted hydrated electron radial distribution function, as calculated by DFT-based simulations with the PBEh-D3 functional, deviate from the true solvation structure.
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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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2
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Jordan CJC, Coons MP, Herbert JM, Verlet JRR. Spectroscopy and dynamics of the hydrated electron at the water/air interface. Nat Commun 2024; 15:182. [PMID: 38167300 PMCID: PMC10762076 DOI: 10.1038/s41467-023-44441-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
The hydrated electron, e-(aq), has attracted much attention as a central species in radiation chemistry. However, much less is known about e-(aq) at the water/air surface, despite its fundamental role in electron transfer processes at interfaces. Using time-resolved electronic sum-frequency generation spectroscopy, the electronic spectrum of e-(aq) at the water/air interface and its dynamics are measured here, following photo-oxidation of the phenoxide anion. The spectral maximum agrees with that for bulk e-(aq) and shows that the orbital density resides predominantly within the aqueous phase, in agreement with supporting calculations. In contrast, the chemistry of the interfacial hydrated electron differs from that in bulk water, with e-(aq) diffusing into the bulk and leaving the phenoxyl radical at the surface. Our work resolves long-standing questions about e-(aq) at the water/air interface and highlights its potential role in chemistry at the ubiquitous aqueous interface.
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Affiliation(s)
| | - Marc P Coons
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - John M Herbert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 4LJ, UK.
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3
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Mato J, Willow SY, Werhahn JC, Xantheas SS. The Back Door to the Surface Hydrated Electron. J Phys Chem Lett 2023; 14:8221-8226. [PMID: 37672781 DOI: 10.1021/acs.jpclett.3c01479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
We use a Mg+ metal to extend the size regime of aqueous clusters to extrapolate to the bulk limit of the vertical detachment energy (VDE) of the solvated electron to >3,200, a value between 1 to over 2 orders of magnitude larger than the one previously measured experimentally or computed theoretically. We relate the VDE to the energy difference between the Mg+(H2O)n and Mg2+(H2O)n systems and the metal's second ionization potential. The extrapolated bulk VDEs of the localized surface electron, which moves away from the metal as n increases, are 1.89 ± 0.01 eV for semiempirical (n ∼ 3,200; PM6-D3H4) and 1.73 ± 0.03 eV (n ∼ 150; HF) and 1.83 ± 0.02 eV (n ∼ 150; MP2) for ab initio, in excellent agreement with the 1.6-1.8 eV range of experimental results. The VDEs converge from above (larger values) to the bulk limit, in a manner that is qualitatively opposite from previous studies and experiments lacking a charged metal, a fact justifying the "back door" approach to the solvated electron.
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Affiliation(s)
- Joani Mato
- Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS J7-10, Richland, Washington 99352, United States
| | - Soohaeng Yoo Willow
- Department of Energy Science, Sungkyunkwan University, Seobu-ro 2066, Suwon 16419, Republic of Korea
| | - Jasper C Werhahn
- Department of Physics E11, Technical University of Munich, James-Franck-Strasse, D-85748 Garching, Germany
| | - Sotiris S Xantheas
- Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS J7-10, Richland, Washington 99352, United States
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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4
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Park SJ, Narvaez WA, Schwartz BJ. Ab Initio Studies of Hydrated Electron/Cation Contact Pairs: Hydrated Electrons Simulated with Density Functional Theory Are Too Kosmotropic. J Phys Chem Lett 2023; 14:559-566. [PMID: 36630724 DOI: 10.1021/acs.jpclett.2c03705] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We have performed the first DFT-based ab initio MD simulations of a hydrated electron (eaq-) in the presence of Na+, a system chosen because ion-pairing behavior in water depends sensitively on the local hydration structure. Experiments show that eaq-'s interact weakly with Na+; the eaq-'s spectrum blue shifts by only a few tens of meV upon ion pairing without changing shape. We find that the spectrum of the DFT-simulated eaq- red shifts and changes shape upon interaction with Na+, in contrast with experiment. We show that this is because the hydration structure of the DFT-simulated eaq- is too ordered or kosmotropic. Conversely, simulations that produce eaq-'s with a less ordered or chaotropic hydration structure form weaker ion pairs with Na+, yielding predicted spectral blue shifts in better agreement with experiment. Thus, ab initio simulations based on hybrid GGA DFT functionals fail to produce the correct solvation structure for the hydrated electron.
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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
| | - Wilberth A Narvaez
- 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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5
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Li X, Jia X, Paz ASP, Cao Y, Glover WJ. Evidence for Water Antibonding Orbital Mixing in the Hydrated Electron from Its Oxygen 1s X-ray Absorption Spectrum. J Am Chem Soc 2022; 144:19668-19672. [PMID: 36251402 DOI: 10.1021/jacs.2c07572] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The X-ray absorption spectrum (XAS) of the hydrated electron (e(aq)-) has been simulated using time-dependent density functional theory with a quantum mechanics/molecular mechanics description. A unique XAS peak at 533 eV is observed with an energy and intensity in quantitative agreement with recent time-resolved experiments, allowing its assignment as arising from water O1s transitions to the singly occupied molecular orbital (SOMO) in which the excess electron resides. The transitions acquire oscillator strength due to the SOMO comprising an admixture of a cavity-localized orbital and water 4a1 and 2b2 antibonding orbitals. The mixing of antibonding orbitals has implications for the strength of couplings between e(aq)- and intramolecular modes of water.
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Affiliation(s)
- Xingpin Li
- NYU Shanghai, 1555 Century Avenue, Shanghai, 200122, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshang Road, Shanghai, 200062, China.,Department of Chemistry, New York University, New York, New York10003, United States
| | - Xiangyu Jia
- NYU Shanghai, 1555 Century Avenue, Shanghai, 200122, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshang Road, Shanghai, 200062, China
| | - Amiel S P Paz
- NYU Shanghai, 1555 Century Avenue, Shanghai, 200122, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshang Road, Shanghai, 200062, China.,Department of Chemistry, New York University, New York, New York10003, United States
| | - Yuquan Cao
- NYU Shanghai, 1555 Century Avenue, Shanghai, 200122, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshang Road, Shanghai, 200062, China.,Department of Chemistry, New York University, New York, New York10003, United States
| | - William J Glover
- NYU Shanghai, 1555 Century Avenue, Shanghai, 200122, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, 3663 Zhongshang Road, Shanghai, 200062, China.,Department of Chemistry, New York University, New York, New York10003, United States
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6
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Narvaez WA, Park SJ, Schwartz BJ. Competitive Ion Pairing and the Role of Anions in the Behavior of Hydrated Electrons in Electrolytes. J Phys Chem B 2022; 126:7701-7708. [PMID: 36166380 DOI: 10.1021/acs.jpcb.2c04463] [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
Experiments have shown that in the presence of electrolytes, the hydrated electron's absorption spectrum experiences a blue shift whose magnitude depends on both the salt concentration and chemical identity. Previous computer simulations have suggested that the spectral blue shift results from the formation of (cation, electron) contact pairs and that the concentration dependence arises because the number of cations simultaneously paired with the electron increases with increasing concentration. In this work, we perform new simulations to build an atomistic picture that explains the effect of salt identity on the observed hydrated electron spectral shifts. We simulate hydrated electrons in the presence of both monovalent (Na+) and divalent (Ca2+) cations paired with both Cl- and a spherical species representing ClO4- anions. Our simulations reproduce the experimental observations that divalent ions produce larger blue shifts of the hydrated electron's spectrum than monovalent ions with the same anion and that perchlorate salts show enhanced blue shifts compared to chloride salts with the same cation. We find that these observations can be explained by competitive ion pairing. With small kosmotropic cations such as Na+ and Ca2+, aqueous chloride salts tend to form (cation, anion) contact pairs, whereas there is little ion pairing between these cations and chaotropic perchlorate anions. Hydrated electrons also strongly interact with these cations, but if the cations are also paired with anions, this affects the free energy of the electron-cation interaction. With chloride salts, hydrated electrons end up in complexes containing multiple cations plus a few anions as well as the electron. Repulsive interactions between the electron and the nearby Cl- anions reduce the cation-induced spectral blue shift of the hydrated electron. With perchlorate salts, hydrated electrons pair with multiple cations without any associated anions, leading to the largest possible cation-induced spectral blue shift. We also see that the reason multivalent cations produce larger spectral blue shifts than monovalent cations is because hydrated electrons are able to simultaneously pair with a larger number of multivalent cations due to a larger free energy of interaction. Overall, the interaction of hydrated electrons with electrolytes fits well with the Hofmeister series, where the electron behaves as an anion that is slightly more able to break water's H-bond structure than chloride.
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Affiliation(s)
- Wilberth A Narvaez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Sanghyun J Park
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, United States
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7
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Signorell R, Winter B. Photoionization of the aqueous phase: clusters, droplets and liquid jets. Phys Chem Chem Phys 2022; 24:13438-13460. [PMID: 35510623 PMCID: PMC9176186 DOI: 10.1039/d2cp00164k] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
This perspective article reviews specific challenges associated with photoemission spectroscopy of bulk liquid water, aqueous solutions, water droplets and water clusters. The main focus lies on retrieving accurate energetics and photoelectron angular information from measured photoemission spectra, and on the question how these quantities differ in different aqueous environments. Measured photoelectron band shapes, vertical binding energies (ionization energies), and photoelectron angular distributions are influenced by various phenomena. We discuss the influences of multiple energy-dependent electron scattering in aqueous environments, and we discuss different energy referencing methods, including the application of a bias voltage to access absolute energetics of solvent and solute. Recommendations how to account for or minimize the influence of electron scattering are provided. The example of the hydrated electron in different aqueous environments illustrates how one can account for electron scattering, while reliable methods addressing parasitic potentials and proper energy referencing are demonstrated for ionization from the outermost valence orbital of neat liquid water. This perspective article reviews specific challenges associated with photoemission spectroscopy of bulk liquid water, aqueous solutions, water droplets and water clusters.![]()
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Affiliation(s)
- Ruth Signorell
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.
| | - Bernd Winter
- Molecular Physics Department, Fritz-Haber-Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14196 Berlin, Germany.
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8
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Narvaez WA, Park SJ, Schwartz BJ. Hydrated Electrons in High-Concentration Electrolytes Interact with Multiple Cations: A Simulation Study. J Phys Chem B 2022; 126:3748-3757. [PMID: 35544344 DOI: 10.1021/acs.jpcb.2c01501] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experimental studies have demonstrated that the hydrated electron's absorption spectrum undergoes a concentration-dependent blue-shift in the presence of electrolytes such as NaCl. The blue-shift increases roughly linearly at low salt concentration but saturates as the solubility limit of the salt is approached. Previous attempts to understand the origin of the concentration-dependent spectral shift using molecular simulation have only examined the interaction between the hydrated electron and a single sodium cation, and these simulations predicted a spectral blue-shift that was an order of magnitude larger than that seen experimentally. Thus, in this paper, we first explore the reasons for the exaggerated spectral blue-shift when a simulated hydrated electron interacts with a single Na+. We find that the issue arises from nonpairwise additivity of the Na+-e- and H2O-e- pseudopotentials used in the simulation. This effect arises because the solvating water molecules donate charge into the empty orbitals of Na+, lowering the effective charge of the cation and thus reducing the excess electron-cation interaction. Careful analysis shows, however, that although this nonpairwise additivity changes the energetics of the electron-Na+ interaction, the forces between the electron, Na+, and water are unaffected, so that mixed quantum/classical (MQC) simulations produce the correct structure and dynamics. With this in hand, we then use MQC simulations to explore the behavior of the hydrated electron as an explicit function of NaCl salt concentration. We find that the simulations correctly reproduce the observed experimental spectral shifting behavior. The reason for the spectral shift is that as the electrolyte concentration increases, the average number of cations simultaneously interacting in contact pairs with the hydrated electron increases from 1.0 at low concentrations to ∼2.5 near the saturation limit. As the number of cations that interact with the electron increases, the cation/electron interactions becomes slightly weaker, so that the corresponding Na+-e- distance increases with increasing salt concentration. We also find that the dielectric constant of the solution plays little role in the observed spectroscopy, so that the electrolyte-dependent spectral shifts of the hydrated electron are directly related to the concentration-dependent number of closely interacting cations.
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Affiliation(s)
- Wilberth A Narvaez
- Department of Chemistry and Biochemistry, University of California, Los Angeles Los Angeles, California 90095-1569 United States
| | - 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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9
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Park SJ, Narvaez WA, Schwartz BJ. How Water-Ion Interactions Control the Formation of Hydrated Electron:Sodium Cation Contact Pairs. J Phys Chem B 2021; 125:13027-13040. [PMID: 34806385 DOI: 10.1021/acs.jpcb.1c08256] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although solvated electrons are a perennial subject of interest, relatively little attention has been paid to the way they behave in aqueous electrolytes. Experimentally, it is known that the hydrated electron's (eaq-) absorption spectrum shifts to the blue in the presence of salts, and the magnitude of the shift depends on the ion concentration and the identities of both the cation and anion. Does the blue-shift result from some type of dielectric effect from the bulk electrolyte, or are there specific interactions between the hydrated electron and ions in solution? Previous work has suggested that eaq- forms contact pairs with aqueous ions such as Na+, leading to the question of what controls the stability of such contact pairs and their possible connection to the observed spectroscopy. In this work, we use mixed quantum/classical simulations to examine the nature of Na+:e- contact pairs in water, using a novel method for quantum umbrella sampling to construct eaq--ion potentials of mean force (PMF). We find that the nature of the contact pair PMF depends sensitively on the choice of the classical interactions used to describe the Na+-water interactions. When the ion-water interactions are slightly stronger, the corresponding cation:e- contact pairs form at longer distances and become free energetically less stable. We show that this is because there is a delicate balance between solvation of the cation, solvation of eaq- and the direct electronic interaction between the cation and the electron, so that small changes in this balance lead to large changes in the formation and stability of e--ion contact pairs. In particular, strengthening the ion-water interactions helps to maintain a favorable local solvation environment around Na+, which in turn forces water molecules in the first solvation shell of the cation to be unfavorably oriented toward the electron in a contact pair; stronger solvation of the cation also reduces the electronic overlap of eaq- with Na+. We also find that the calculated spectra of different models of Na+:e- contact pairs do not shift monotonically with cation-electron distance, and that the calculated spectral shifts are about an order of magnitude larger than experiment, suggesting that isolated contact pairs are not the sole explanation for the blue-shift of the hydrated electron's spectrum in the presence of electrolytes.
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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
| | - Wilberth A Narvaez
- 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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10
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Abstract
![]()
Cluster-size-resolved
ultrafast dynamics of the solvated electron
in neutral water clusters with n = 3 to ∼200
molecules are studied with pump–probe time-of-flight mass spectrometry
after below band gap excitation. For the smallest clusters, no longer-lived
(>100–200 fs) hydrated electrons were detected, indicating
a minimum size of n ∼ 14 for being able to
sustain hydrated electrons. Larger clusters show a systematic increase
of the number of hydrated electrons per molecule on the femtosecond
to picosecond time scale. We propose that with increasing cluster
size the underlying dynamics is governed by more effective electron
formation processes combined with less effective electron loss processes,
such as ultrafast hydrogen ejection and recombination. It appears
unlikely that any size dependence of the solvent relaxation dynamics
would be reflected in the observed time-resolved ion yields.
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Affiliation(s)
- Loren Ban
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Bruce L Yoder
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Ruth Signorell
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
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11
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Sau A, Nagarajan K, Patrahau B, Lethuillier-Karl L, Vergauwe RMA, Thomas A, Moran J, Genet C, Ebbesen TW. Modifying Woodward-Hoffmann Stereoselectivity Under Vibrational Strong Coupling. Angew Chem Int Ed Engl 2021; 60:5712-5717. [PMID: 33305864 PMCID: PMC7986062 DOI: 10.1002/anie.202013465] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/18/2020] [Indexed: 11/23/2022]
Abstract
Vibrational strong coupling (VSC) has recently been shown to change the rate and chemoselectivity of ground‐state chemical reactions via the formation of light–matter hybrid polaritonic states. However, the observation that vibrational‐mode symmetry has a large influence on charge‐transfer reactions under VSC suggests that symmetry considerations could be used to control other types of chemical selectivity through VSC. Here, we show that VSC influences the stereoselectivity of the thermal electrocyclic ring opening of a cyclobutene derivative, a reaction which follows the Woodward–Hoffmann rules. The direction of the change in stereoselectivity depends on the vibrational mode that is coupled, as do changes in rate and reaction thermodynamics. These results on pericyclic reactions confirm that symmetry plays a key role in chemistry under VSC.
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Affiliation(s)
- Abhijit Sau
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
| | | | - Bianca Patrahau
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
| | | | | | - Anoop Thomas
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
| | - Joseph Moran
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
| | - Cyriaque Genet
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
| | - Thomas W Ebbesen
- University of Strasbourg, CNRS, ISIS & icFRC, 67000, Strasbourg, France
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12
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Park SJ, Schwartz BJ. Evaluating Simple Ab Initio Models of the Hydrated Electron: The Role of Dynamical Fluctuations. J Phys Chem B 2020; 124:9592-9603. [PMID: 33078930 DOI: 10.1021/acs.jpcb.0c06356] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite its importance in electron transfer reactions and radiation chemistry, there has been disagreement over the fundamental nature of the hydrated electron, such as whether or not it resides in a cavity. Mixed quantum/classical simulations of the hydrated electron give different structures depending on the pseudopotential employed, and ab initio models of computational necessity use small numbers of water molecules and/or provide insufficient statistics to compare to experimental observables. A few years ago, Kumar et al. (J. Phys. Chem. A 2015, 119, 9148) proposed a minimalist ab initio model of the hydrated electron with only a small number of explicitly treated water molecules plus a polarizable continuum model (PCM). They found that the optimized geometry had four waters arranged tetrahedrally around a central cavity, and that the calculated vertical detachment energy and radius of gyration agreed well with experiment, results that were largely independent of the level of theory employed. The model, however, is based on a fixed structure at 0 K and does not explicitly incorporate entropic contributions or the thermal fluctuations that should be associated with the room-temperature hydrated electron. Thus, in this paper, we extend the model of Kumar et al. by running Born-Oppenheimer molecular dynamics (BOMD) of a small number of water molecules with an excess electron plus PCM at room temperature. We find that when thermal fluctuations are introduced, the level of theory chosen becomes critical enough when only four waters are used that one of the waters dissociates from the cluster with certain density functionals. Moreover, even with an optimally tuned range-separated hybrid functional, at room temperature the tetrahedral orientation of the 0 K first-shell waters is entirely lost and the central cavity collapses, a process driven by the fact that the explicit water molecules prefer to make H-bonds with each other more than with the excess electron. The resulting average structure is quite similar to that produced by a noncavity mixed quantum/classical model, so that the minimalist 4-water BOMD models suffer from problems similar to those of noncavity models, such as predicting the wrong sign of the hydrated electron's molar solvation volume. We also performed BOMD with 16 explicit water molecules plus an extra electron and PCM. We find that the inclusion of an entire second solvation shell of explicit water leads to little change in the outcome from when only four waters were used. In fact, the 16-water simulations behave much like those of water cluster anions, in which the electron localizes at the cluster surface, showing that PCM is not acceptable for use in minimalist models to describe the behavior of the bulk hydrated electron. For both the 4- and 16-water models, we investigate how the introduction of thermal motions alters the predicted absorption spectrum, vertical detachment energy, and resonance Raman spectrum of the simulated hydrated electron. We also present a set of structural criteria that can be used to numerically determine how cavity-like (or not) a particular hydrated electron model is. All of the results emphasize that the hydrated electron is a statistical object whose properties are inadequately captured using only a small number of explicit waters, and that a proper treatment of thermal fluctuations is critical to understanding the hydrated electron's chemical and physical behavior.
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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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13
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Ban L, West CW, Chasovskikh E, Gartmann TE, Yoder BL, Signorell R. Below Band Gap Formation of Solvated Electrons in Neutral Water Clusters? J Phys Chem A 2020; 124:7959-7965. [PMID: 32878434 PMCID: PMC7536715 DOI: 10.1021/acs.jpca.0c06935] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/01/2020] [Indexed: 01/25/2023]
Abstract
Below band gap formation of solvated electrons in neutral water clusters using pump-probe photoelectron imaging is compared with recent data for liquid water and with above band gap excitation studies in liquid and clusters. Similar relaxation times on the order of 200 fs and 1-2 ps are retrieved for below and above band gap excitation, in both clusters and liquid. The independence of the relaxation times from the generation process indicates that these times are dominated by the solvent response, which is significantly slower than the various solvated electron formation processes. The analysis of the temporal evolution of the vertical electron binding energy and the electron binding energy at half-maximum suggests a dependence of the solvation time on the binding energy.
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Affiliation(s)
- Loren Ban
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Christopher W. West
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Egor Chasovskikh
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Thomas E. Gartmann
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Bruce L. Yoder
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
| | - Ruth Signorell
- ETH Zurich, Department of Chemistry
and Applied Biosciences, Vladimir-Prelog-Weg 2, CH-8093 Zurich, Switzerland
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14
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Glover WJ, Schwartz BJ. The Fluxional Nature of the Hydrated Electron: Energy and Entropy Contributions to Aqueous Electron Free Energies. J Chem Theory Comput 2020; 16:1263-1270. [PMID: 31914315 DOI: 10.1021/acs.jctc.9b00496] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There has been a great deal of recent controversy over the structure of the hydrated electron and whether it occupies a cavity or contains a significant number of interior waters (noncavity). The questions we address in this work are, from a free energy perspective, how different are these proposed structures? Do the different structures all lie along a single continuum, or are there significant differences (i.e., free energy barriers) between them? To address these questions, we have performed a series of one-electron calculations using umbrella sampling with quantum biased molecular dynamics along a coordinate that directly reflects the number of water molecules in the hydrated electron's interior. We verify that a standard cavity model of the hydrated electron behaves essentially as a hard sphere: the model is dominated by repulsion at short range such that water is expelled from a local volume around the electron, leading to a water solvation shell like that of a pseudohalide ion. The repulsion is much larger than thermal energies near room temperature, explaining why such models exhibit properties with little temperature dependence. On the other hand, our calculations reveal that a noncavity model is highly fluxional, meaning that thermal motions cause the number of interior waters to fluctuate from effectively zero (i.e., a cavity-type electron) to potentially above the bulk water density. The energetic contributions in the noncavity model are still repulsive in the sense that they favor cavity formation, so the fluctuations in structure are driven largely by entropy: the entropic cost for expelling water from a region of space is large enough that some water is still driven into the electron's interior. As the temperature is lowered and entropy becomes less important, the noncavity electron's structure is predicted to become more cavity-like, consistent with the observed temperature dependence of the hydrated electron's properties. Thus, we argue that although the specific noncavity model we study overestimates the preponderance of fluctuations involving interior water molecules, with appropriate refinements to correctly capture the true average number of interior waters and molar solvation volume, a fluxional model likely makes the most sense for understanding the various experimental properties of the hydrated electron.
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Affiliation(s)
- William J Glover
- NYU Shanghai , 1555 Century Ave. , Pudong, Shanghai , China 200122.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai , 3663 Zhongshang Road , Shanghai , China 200062.,Department of Chemistry , New York University , New York , New York 10003 , United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry , University of California, Los Angeles , 607 Charles E. Young Drive East , Los Angeles , California 90095-1569 , United States
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15
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Structure and spectrum of the hydrated electron. A combined quantum chemical statistical mechanical simulation. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Dasgupta S, Rana B, Herbert JM. Ab Initio Investigation of the Resonance Raman Spectrum of the Hydrated Electron. J Phys Chem B 2019; 123:8074-8085. [PMID: 31442044 DOI: 10.1021/acs.jpcb.9b04895] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
According to the conventional picture, the aqueous or "hydrated" electron, e-(aq), occupies an excluded volume (cavity) in the structure of liquid water. However, simulations with certain one-electron models predict a more delocalized spin density for the unpaired electron, with no distinct cavity structure. It has been suggested that only the latter (non-cavity) structure can explain the hydrated electron's resonance Raman spectrum, although this suggestion is based on calculations using empirical frequency maps developed for neat liquid water, not for e-(aq). All-electron ab initio calculations presented here demonstrate that both cavity and non-cavity models of e-(aq) afford significant red-shifts in the O-H stretching region. This effect is nonspecific and arises due to electron penetration into frontier orbitals of the water molecules. Only the conventional cavity model, however, reproduces the splitting of the H-O-D bend (in isotopically mixed water) that is observed experimentally and arises due to the asymmetric environments of the hydroxyl moieties in the electron's first solvation shell. We conclude that the cavity model of e-(aq) is more consistent with the measured resonance Raman spectrum than is the delocalized, non-cavity model, despite previous suggestions to the contrary. Furthermore, calculations with hybrid density functionals and with Hartree-Fock theory predict that non-cavity liquid geometries afford only unbound (continuum) states for an extra electron, whereas in reality this energy level should lie more than 3 eV below vacuum level. As such, the non-cavity model of e-(aq) appears to be inconsistent with available vibrational spectroscopy, photoelectron spectroscopy, and quantum chemistry.
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Affiliation(s)
- Saswata Dasgupta
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - Bhaskar Rana
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - John M Herbert
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
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17
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Gartmann T, Ban L, Yoder BL, Hartweg S, Chasovskikh E, Signorell R. Relaxation Dynamics and Genuine Properties of the Solvated Electron in Neutral Water Clusters. J Phys Chem Lett 2019; 10:4777-4782. [PMID: 31382737 PMCID: PMC6734797 DOI: 10.1021/acs.jpclett.9b01802] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/05/2019] [Indexed: 05/27/2023]
Abstract
We have investigated the solvation dynamics and the genuine binding energy and photoemission anisotropy of the solvated electron in neutral water clusters with a combination of time-resolved photoelectron velocity map imaging and electron scattering simulations. The dynamics was probed with a UV probe pulse following above-band-gap excitation by an EUV pump pulse. The solvation dynamics is completed within about 2 ps. Only a single band is observed in the spectra, with no indication for isomers with distinct binding energies. Data analysis with an electron scattering model reveals a genuine binding energy in the range of 3.55-3.85 eV and a genuine anisotropy parameter in the range of 0.51-0.66 for the ground-state hydrated electron. All of these observations coincide with those for liquid bulk, which is rather unexpected for an average cluster size of 300 molecules.
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18
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Abstract
The partial molar volume of the hydrated electron was investigated with pulse radiolysis and transient absorption by measuring the pressure dependence of the equilibrium constant for e-aq + NH4+ ⇔ H + NH3. At 2 kbar pressure, the equilibrium constant decreases relative to 1 bar by only 6%. Using tabulated molar volumes for ammonia and ammonium, we have the result V̅(e-aq) - V̅(H) = 11.3 cm3/mol at 25 °C, confirming that V̅(e-aq) is positive and even larger than the hydrophobic H atom. Assuming on the basis of recent molecular dynamics simulations that the molar volume of the H atom is somewhat less than that of H2, we estimate V̅(e-aq) = 26 ± 6 cm3/mol. The positive molar volume is consistent with an electron that exists largely in a small solvent void (cavity), ruling out a recent model ( Larsen , R. E. ; Glover , W. J. ; Schwartz , B. J. Science 2010 , 329 , 65 - 69 ) that suggests a noncavity structure with negative molar volume.
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Affiliation(s)
- Ireneusz Janik
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - Alexandra Lisovskaya
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
| | - David M Bartels
- Radiation Laboratory , University of Notre Dame , Notre Dame , Indiana 46556 , United States
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19
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Abstract
Electron attachment onto water clusters to form water cluster anions is studied by varying the point of electron attachment along a molecular beam axis and probing the produced cluster anions using photoelectron spectroscopy. The results show that the point of electron attachment has a clear effect on the final distribution of isomers for a cluster containing 78 water molecules, with isomer I formed preferentially near the start of the expansion and isomer II formed preferentially once the molecular beam has progressed for several millimeters. These changes can be accounted for by the cluster growth rate along the beam. Near the start of the expansion, cluster growth is proceeding rapidly with condensing water molecules solvating the electron, while further along the expansion, the growth has terminated and electrons are attached to large and cold preformed clusters, leading to the isomer associated with a loosely bound surface state.
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Affiliation(s)
- Aude Lietard
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
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20
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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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21
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Wang Y, Guo H, Zheng Q, Saidi WA, Zhao J. Tuning Solvated Electrons by Polar-Nonpolar Oxide Heterostructure. J Phys Chem Lett 2018; 9:3049-3056. [PMID: 29767527 DOI: 10.1021/acs.jpclett.8b00938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Solvated electron states at the oxide/aqueous interface represent the lowest energy charge-transfer pathways, thereby playing an important role in photocatalysis and electronic device applications. However, their energies are usually higher than the conduction band minimum (CBM), which makes the solvated electrons difficult to utilize in charge-transfer processes. Thus it is essential to stabilize the energy of the solvated electron states. Taking LaAlO3/SrTiO3 (LAO/STO) oxide heterostructure with H2O-adsorbed monolayer as a prototypical system, we show using DFT and ab initio time-dependent nonadiabatic molecular dynamics simulation that the energy and dynamics of solvated electrons can be tuned by the electric field in the polar-nonpolar oxide heterostructure. In particular, for LAO/STO with p-type interface, the CBM is contributed by the solvated electron state when LAO is thicker than four unit cells. Furthermore, the solvated electron band minimum can be partially occupied when LAO is thicker than eight unit cells. We propose that the tunability of solvated electron states can be achieved on polar-nonpolar oxide heterostructure surfaces as well as on ferroelectric oxides, which is important for charge and proton transfer at oxide/aqueous interfaces.
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Affiliation(s)
- Yanan Wang
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Hongli Guo
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education , Wuhan University , Wuhan 430072 , China
| | - Qijing Zheng
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Wissam A Saidi
- Department of Mechanical Engineering and Materials Science , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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22
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Hertzog M, Rudquist P, Hutchison JA, George J, Ebbesen TW, Börjesson K. Voltage-Controlled Switching of Strong Light-Matter Interactions using Liquid Crystals. Chemistry 2017; 23:18166-18170. [PMID: 29155469 PMCID: PMC5814857 DOI: 10.1002/chem.201705461] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Indexed: 11/13/2022]
Abstract
We experimentally demonstrate a fine control over the coupling strength of vibrational light-matter hybrid states by controlling the orientation of a nematic liquid crystal. Through an external voltage, the liquid crystal is seamlessly switched between two orthogonal directions. Using these features, for the first time, we demonstrate electrical switching and increased Rabi splitting through transition dipole moment alignment. The C-Nstr vibration on the liquid crystal molecule is coupled to a cavity mode, and FT-IR is used to probe the formed vibropolaritonic states. A switching ratio of the Rabi splitting of 1.78 is demonstrated between the parallel and the perpendicular orientation. Furthermore, the orientational order increases the Rabi splitting by 41 % as compared to an isotropic liquid. Finally, by examining the influence of molecular alignment on the Rabi splitting, the scalar product used in theoretical modeling between light and matter in the strong coupling regime is verified.
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Affiliation(s)
- Manuel Hertzog
- Department of Chemistry and Molecular BiologyUniversity of GothenburgKemigården 4412 96GothenburgSweden
| | - Per Rudquist
- Department of Microtechnology and Nanoscience, MC2Chalmers University of TechnologyKemivägen 9412 96GothenburgSweden
| | - James A. Hutchison
- University of Strasbourg, CNRS, ISIS & icFRC8 allée Gaspard MongeStrasbourg67000France
| | - Jino George
- University of Strasbourg, CNRS, ISIS & icFRC8 allée Gaspard MongeStrasbourg67000France
| | - Thomas W. Ebbesen
- University of Strasbourg, CNRS, ISIS & icFRC8 allée Gaspard MongeStrasbourg67000France
| | - Karl Börjesson
- Department of Chemistry and Molecular BiologyUniversity of GothenburgKemigården 4412 96GothenburgSweden
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23
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Farr EP, Zho CC, Challa JR, Schwartz BJ. Temperature dependence of the hydrated electron’s excited-state relaxation. II. Elucidating the relaxation mechanism through ultrafast transient absorption and stimulated emission spectroscopy. J Chem Phys 2017; 147:074504. [DOI: 10.1063/1.4985906] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Erik P. Farr
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
| | - Chen-Chen Zho
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
| | - Jagannadha R. Challa
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
| | - Benjamin J. Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
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24
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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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25
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Affiliation(s)
- John M. Herbert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Marc P. Coons
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
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26
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Luckhaus D, Yamamoto YI, Suzuki T, Signorell R. Genuine binding energy of the hydrated electron. SCIENCE ADVANCES 2017; 3:e1603224. [PMID: 28508051 PMCID: PMC5409453 DOI: 10.1126/sciadv.1603224] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/02/2017] [Indexed: 05/24/2023]
Abstract
The unknown influence of inelastic and elastic scattering of slow electrons in water has made it difficult to clarify the role of the solvated electron in radiation chemistry and biology. We combine accurate scattering simulations with experimental photoemission spectroscopy of the hydrated electron in a liquid water microjet, with the aim of resolving ambiguities regarding the influence of electron scattering on binding energy spectra, photoelectron angular distributions, and probing depths. The scattering parameters used in the simulations are retrieved from independent photoemission experiments of water droplets. For the ground-state hydrated electron, we report genuine values devoid of scattering contributions for the vertical binding energy and the anisotropy parameter of 3.7 ± 0.1 eV and 0.6 ± 0.2, respectively. Our probing depths suggest that even vacuum ultraviolet probing is not particularly surface-selective. Our work demonstrates the importance of quantitative scattering simulations for a detailed analysis of key properties of the hydrated electron.
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Affiliation(s)
- David Luckhaus
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Yo-ichi Yamamoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-Ku, Kyoto 606-8502, Japan
| | - Toshinori Suzuki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-Ku, Kyoto 606-8502, Japan
| | - Ruth Signorell
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
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27
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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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28
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Glover WJ, Schwartz BJ. Short-Range Electron Correlation Stabilizes Noncavity Solvation of the Hydrated Electron. J Chem Theory Comput 2016; 12:5117-5131. [PMID: 27576177 DOI: 10.1021/acs.jctc.6b00472] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The hydrated electron, e-(aq), has often served as a model system to understand the influence of condensed-phase environments on electronic structure and dynamics. Despite over 50 years of study, however, the basic structure of e-(aq) is still the subject of controversy. In particular, the structure of e-(aq) was long assumed to be an electron localized within a solvent cavity, in a manner similar to halide solvation. Recently, however, we suggested that e-(aq) occupies a region of enhanced water density with little or no discernible cavity. The potential we developed was only subtly different from those that give rise to a cavity solvation motif, which suggests that the driving forces for noncavity solvation involve subtle electron-water attractive interactions at close distances. This leads to the question of how dispersion interactions are treated in simulations of the hydrated electron. Most dispersion potentials are ad hoc or are not designed to account for the type of close-contact electron-water overlap that might occur in the condensed phase, and where short-range dynamic electron correlation is important. To address this, in this paper we develop a procedure to calculate the potential energy surface between a single water molecule and an excess electron with high-level CCSD(T) electronic structure theory. By decomposing the electron-water potential into its constituent energetic contributions, we find that short-range electron correlation provides an attraction of comparable magnitude to the mean-field interactions between the electron and water. Furthermore, we find that by reoptimizing a popular cavity-forming one-electron model potential to better capture these attractive short-range interactions, the enhanced description of correlation predicts a noncavity e-(aq) with calculated properties in better agreement with experiment. Although much attention has been placed on the importance of long-range dispersion interactions in water cluster anions, our study reveals that largely unexplored short-range correlation effects are crucial in dictating the solvation structure of the condensed-phase hydrated electron.
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Affiliation(s)
- William J Glover
- NYU-ECNU Center for Computational Chemistry, New York University Shanghai , Shanghai, 200122, China.,Department of Chemistry, New York University , New York, New York 10003, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
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29
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Coons MP, You ZQ, Herbert JM. The Hydrated Electron at the Surface of Neat Liquid Water Appears To Be Indistinguishable from the Bulk Species. J Am Chem Soc 2016; 138:10879-86. [DOI: 10.1021/jacs.6b06715] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marc P. Coons
- Department of Chemistry and
Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Zhi-Qiang You
- Department of Chemistry and
Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - John M. Herbert
- Department of Chemistry and
Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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