Photoelectron spectroscopy of hydrated electron cluster anions, (H2O)−<i>n</i>=2–69

Coe, James V.; Lee, G. H.; Eaton, J. G.; Arnold, Susan T.; Sarkas, H. W.; Bowen, Kit H.; Ludewigt, C.; Haberland, Hellmut; Worsnop, Douglas R.

doi:10.1063/1.457805

Cited by 524 publications

(431 citation statements)

References 42 publications

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“…(12)(13)(14)(15) Already a water dimer is capable of binding an excess electron, (12) however, its character is very different from the bulk hydrated species. In small systems, these are weakly bound and very diffuse dipole-bound electrons, which reside at the exterior of the water cluster.…”

Section: Introductionmentioning

confidence: 99%

Structure, Dynamics, and Reactivity of Hydrated Electrons by Ab Initio Molecular Dynamics

et al. 2011

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Understanding the properties of hydrated electrons, which were first observed using pulse radiolysis of water in 1962, is crucial because they are key species in many radiation chemistry processes. Although time-resolved spectroscopic studies and molecular simulations have shown that an electron in water (prepared, for example, by water photoionization) relaxes quickly to a localized, cavity-like structure similar to 2.5 angstrom in radius, this picture has recently been questioned. In another experimental approach, negatively charged water clusters of increasing size were studied with photoelectron and IR spectroscopies. Although small clusters can bind an excess electron, their character is very different from bulk hydrated species. As data on electron binding in liquid water have become directly accessible experimentally, the cluster-to-bulk extrapolations have become a topic of lively debate. Quantum electronic structure calculations addressing experimental measurables have, until recently, been largely limited to small clusters; extended systems were approached mainly with pseudopotential calculations combining a classical description of water with a quantum mechanical treatment of the excess electron. In this Account, we discuss our investigations of electrons solvated in water by means of ab initio molecular dynamics simulations. This approach, applied to a model system of a negatively charged cluster of 32 water molecules, allows us to characterize structural, dynamical, and reactive aspects of the hydrated electron using all of the system's valence electrons. We show that under ambient conditions, the electron localizes into a cavity close to the surface of the liquid cluster. This cavity is, however, more flexible and accessible to water molecules than an analogous area around negatively charged ions. The dynamical process of electron attachment to a neutral water cluster is strongly temperature dependent. Under ambient conditions, the electron relaxes in the liquid cluster and becomes indistinguishable from an equilibrated, solvated electron on a picosecond time scale. In contrast, for solid, cryogenic systems, the electron only partially localizes outside of the cluster, being trapped in a metastable, weakly bound "cushion-like" state. Strongly bound states under cryogenic conditions could only be prepared by cooling equilibrated, liquid, negatively charged clusters. These calculations allow us to rationalize how different isomers of electrons in cryogenic clusters can be observed experimentally. Our results also bring into question the direct extrapolation of properties of cryogenic, negatively charged water clusters to those of electrons in the bulk liquid. Ab initio molecular dynamics represents a unique computational tool for investigating the reactivity of the solvated electron in water. As a prototype, the electron proton reaction was followed in the 32-water cluster. In accord with experiment, the molecular mechanism is a proton transfer process that is not diffusion limited, but rat...

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Section: Introductionmentioning

confidence: 99%

Structure, Dynamics, and Reactivity of Hydrated Electrons by Ab Initio Molecular Dynamics

et al. 2011

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“…116 The (H 2 O) n -mass spectrum is dominated by peaks at n = 2, 6, 7, and 11. 113,116,145 The origin of this intensity pattern is still under debate.…”

Section: General Considerationsmentioning

confidence: 99%

A Drude-model approach to dispersion interactions in dipole-bound anions

Wang¹,

Jordan²

2001

The Journal of Chemical Physics

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A one-electron model potential for calculating the binding energy of an excess electron interacting with polar molecules and their clusters is described. The unique feature of this potential is the treatment of polarization and dispersion effects by means of a Drude model. The approach is tested by calculating the energies for binding an excess electron to HCN, (HCN)2, HNC, and (HNC)2. The model potential results are found to be in good agreement with the predictions of high-level all-electron calculations.

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“…[7] the binding energies of internal (solvated) states in clusters of a varying number of molecules are calculated. Recent experiments [8] seem to indicate that these energies may be too large by as much as 0.5 to 1 eV.…”

Section: The Excess Electron In Watermentioning

confidence: 99%

Are Models of Anion Hydration Overbound ? The Solvation of the Electron and Chloride Anion Compared

Sprik

1991

J. Phys. IV France

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Photoelectron spectroscopy of hydrated electron cluster anions, (H2O)−n=2–69

Cited by 524 publications

References 42 publications

Structure, Dynamics, and Reactivity of Hydrated Electrons by Ab Initio Molecular Dynamics

Structure, Dynamics, and Reactivity of Hydrated Electrons by Ab Initio Molecular Dynamics

A Drude-model approach to dispersion interactions in dipole-bound anions

Are Models of Anion Hydration Overbound ? The Solvation of the Electron and Chloride Anion Compared

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