Confinement effect on the hydrated electron behaviour

Coudert, François‐Xavier; Boutin, Anne

doi:10.1016/j.cplett.2006.07.023

Cited by 9 publications

(9 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The second salient feature is the lack of any significant confinement effect on the absorption spectrum at 20 ns suggesting that the electron is solvated near the center of the pore where the water has more bulklike properties. Our findings are different than what was observed for water trapped in NaX and NaY zeolites, − where a blue spectral shift of the absorption spectrum to that observed for hydrated electrons in confined water at 0.1 μs following two-photon excitation of naphthalene in NaX submerged in H 2 O was observed. , For a 0.4 nm pore the hydrated electron spectrum was blue-shifted by 55 nm (0.14 eV) relative to that of bulk water. This spectral shift becomes more important when the pore size decreases, and changes direction, moving toward the red, at low water loadings .…”

Section: Resultscontrasting

confidence: 99%

Nanosecond Pulse Radiolysis of Nanoconfined Water

et al. 2012

View full text Add to dashboard Cite

The radiation chemistry of water in 1 and 57 nm pore diameter controlled pore glass is studied using nanosecond pulse radiolysis and compared to that of the bulk. The absorption spectrum of the solvated electron shows little dependence on the pore size suggesting that they solvate within the pore. It is shown that the reaction rate of the solvated electron increases dramatically with decreasing pore size, going from 6.8 × 10 6 s −1 in the bulk to 34.7 × 10 6 s −1 in a 1 nm pore. The initial yield (at 20 ns) shows an increase of 2.03 ± 0.01 in a 1 nm pore relative to the bulk. Formation of the solvated electron most likely occurs by an energy transfer process that occurs at the interface followed by diffusion into the pore.

show abstract

Section: Resultscontrasting

confidence: 99%

Nanosecond Pulse Radiolysis of Nanoconfined Water

et al. 2012

View full text Add to dashboard Cite

show abstract

“…That is, the spread in these energies is largely accounted for by the variation in the cavity size. The same anticorrelation was observed in the MQC calculations of Coudert and Boutin, 33 for − hyd e in nanoconfined water pools in zeolites, and Rossky and Schnitker, 23 for the hydrated electron in bulk water.…”

Section: Energetics and The Absorption Spectrumsupporting

confidence: 78%

The Structure of the Hydrated Electron. Part 2. A Mixed Quantum/Classical Molecular Dynamics Embedded Cluster Density Functional Theory: Single−Excitation Configuration Interaction Study

et al. 2007

View full text Add to dashboard Cite

Adiabatic mixed quantum/classical (MQC) molecular dynamics (MD) simulations were used to generate snapshots of the hydrated electron in liquid water at 300 K. Water cluster anions that include two complete solvation shells centered on the hydrated electron were extracted from the MQC MD simulations and embedded in a roughly 18 Å x 18 Å x 18 Å matrix of fractional point charges designed to represent the rest of the solvent. Density functional theory (DFT) with the Becke-Lee-Yang-Parr functional and single-excitation configuration interaction (CIS) methods were then applied to these embedded clusters. The salient feature of these hybrid DFT(CIS)/MQC MD calculations is significant transfer (ca. 18%) of the excess electron's charge density into the 2p orbitals of oxygen atoms in OH groups forming the solvation cavity. We used the results of these calculations to examine the structure of the singly occupied and the lower unoccupied molecular orbitals, the density of states, the absorption spectra in the visible and ultraviolet, the hyperfine coupling (hfc) tensors, and the infrared (IR) and Raman spectra of these embedded water cluster anions. The calculated hfc tensors were used to compute the The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC-02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. Electron Paramagnetic Resonance (EPR) and Electron Spin Echo Envelope Modulation(ESEEM) spectra for the hydrated electron that compared favorably to the experimental spectra of trapped electrons in alkaline ice. The calculated vibrational spectra of the hydrated electron are consistent with the red-shifted bending and stretching frequencies observed in resonance Raman experiments. In addition to reproducing the visible/near IR absorption spectrum, the hybrid DFT model also accounts for the hydrated electron's 190-nm absorption band in the ultraviolet. Thus, our study suggests that to explain several important experimentally observed properties of the hydrated electron, many-electron effects must be accounted for: one-electron models that do not allow for mixing of the excess electron density with the frontier orbitals of the first-shell solvent molecules cannot explain the observed magnetic, vibrational, and electronic spectroscopy of this species. Despite the need for multielectron effects to explain these important properties, the ensemble-averaged radial wavefunctions and energetics of the highest occupied and three lowest unoccupied orbitals of the hydrated electrons in our hybrid model are close to the s-and p-like states obtained in one-electron models. Thus, one-electron models can provide...

show abstract

“…The results presented here provide a consistent picture of both the short and long-time dynamics of the hydrated electron. They facilitate further investigations into the a pplica-bility of traditional ion diffusion models, water reorientation in the presence of anions [63], and the seemingly anomalous hydrated electron diffusion at lowtemperatures [7] and within confined systems [32].…”

Section: Resultsmentioning

confidence: 99%

“…The electron, confined to the ground state, is represented by a wavefunction that corresponds to the instantaneous nuclear configuration. Our methodology has been previously employed for the hydrated electron at different thermodynamic states [30,31], in confined media [32], and in electron-cation pairs [33,34,35,36].…”

mentioning

confidence: 99%

Mechanism and kinetics of hydrated electron diffusion

Tay¹,

Coudert²,

Boutin³

2008

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

Molecular dynamics simulations are used to study the mechanism and kinetics of hydrated electron diffusion. The electron center of mass is found to exhibit Brownian-type behavior with a diffusion coefficient considerably greater than that of the solvent. As previously postulated by both experimental and theoretical works, the instantaneous response of the electron to the librational motions of surrounding water molecules constitutes the principal mode of motion. The diffusive mechanism can be understood within the traditional framework of transfer diffusion processes, where the diffusive step is akin to the exchange of an extramolecular electron between neighboring water molecules. This is a second-order process with a computed rate constant of 5.0 ps(-1) at 298 K. In agreement with experiment the electron diffusion exhibits Arrhenius behavior over the temperature range of 298-400 K. We compute an activation energy of 8.9 kJ mol(-1). Through analysis of Arrhenius plots and the application of a simple random walk model it is demonstrated that the computed rate constant for exchange of an excess electron is indeed the phenomenological rate constant associated with the diffusive process.

show abstract

Confinement effect on the hydrated electron behaviour

Cited by 9 publications

References 32 publications

Nanosecond Pulse Radiolysis of Nanoconfined Water

Nanosecond Pulse Radiolysis of Nanoconfined Water

The Structure of the Hydrated Electron. Part 2. A Mixed Quantum/Classical Molecular Dynamics Embedded Cluster Density Functional Theory: Single−Excitation Configuration Interaction Study

Mechanism and kinetics of hydrated electron diffusion

Contact Info

Product

Resources

About