On the reactions of hydrated electrons with OH⋅ and H3O+. Analysis of photoionization experiments

Goulet, T.; Jay‐Gerin, Jean‐Paul

doi:10.1063/1.462751

Cited by 76 publications

(111 citation statements)

References 75 publications

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“…The appropriate form of the distribution function depends on the ionization mechanism and is generally assumed to be either a Gaussian or an exponential function. Similar to previous reports, [10][11][12]19,20 we find that using either of these distribution functions for the initial ejection length fits the data equally well at all excitation energies. Additionally, the wide range of energies in our study allows us to test systematically how the choice of distribution function affects the values of ͗r 0 ͘ that come from fitting the data.…”

Section: ͑5͒supporting

confidence: 91%

“…The framework for describing the time-dependent survival probability of an electron as a function of its ejection length r 0 is described separately by Pimblott 11 and by Goulet and Jay-Gerin. 10 Although these authors use slightly different approaches, the result is the same in both derivations, with the primary difference between their methods being the way that they obtain the time-dependent population of electrons P͑t͒ for a given spatial distribution of the hydroxyl radical, hydronium ion, and electron. Both methods require sampling many discrete configurations of the initial distribution in order to obtain the ensemble average of P͑t͒, for which there is no analytical solution.…”

Section: A Kinetic Modelmentioning

confidence: 99%

“…Numerical integration has the advantage of allowing us to fit the data directly using a least-squares routine, rather than visually estimating the best fit from a series of precalculated decay curves, as is often done. 10,11 Using an initial radial distribution of electrons with the form of either a Gaussian function,…”

Section: A Kinetic Modelmentioning

confidence: 99%

“…Quantitative models that account for the relative diffusion and reaction rates of the various species successfully reproduce the time-dependent survival probability of the electron following ionization, thus revealing the average electron ejection length, which is a key feature of the initial product distribution. 10,11 An important result from previous measurements of the geminate recombination of the electron is that the survival probability, and therefore the ejection distance, strongly depends on the excitation energy. Work from a decade ago, using two-photon excitation to study total ionization energies in the range of 7.3-10.1 eV, showed that the average ejection length of electrons remains roughly constant below a threshold of about 9 -9.5 eV, but increases significantly above that energy.…”

Section: Introductionmentioning

confidence: 99%

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Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV

Elles

Jailaubekov

Crowell

et al. 2006

The Journal of Chemical Physics

122

192

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Transient absorption measurements monitor the geminate recombination kinetics of solvated electrons following two-photon ionization of liquid water at several excitation energies in the range from 8.3 to 12.4 eV. Modeling the kinetics of the electron reveals its average ejection length from the hydronium ion and hydroxyl radical counterparts and thus provides insight into the ionization mechanism. The electron ejection length increases monotonically from roughly 0.9 nm at 8.3 eV to nearly 4 nm at 12.4 eV, with the increase taking place most rapidly above 9.5 eV. We connect our results with recent advances in the understanding of the electronic structure of liquid water and discuss the nature of the ionization mechanism as a function of excitation energy. The isotope dependence of the electron ejection length provides additional information about the ionization mechanism. The electron ejection length has a similar energy dependence for two-photon ionization of liquid D 2 O, but is consistently shorter than in H 2 O by about 0.3 nm across the wide range of excitation energies studied.

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Section: ͑5͒supporting

confidence: 91%

Section: A Kinetic Modelmentioning

confidence: 99%

Section: A Kinetic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV

Elles

Jailaubekov

Crowell

et al. 2006

The Journal of Chemical Physics

122

192

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“…In 11,12 . Analysis of kinetic studies 6 suggests a barrier to the "contact" reaction of the electron-proton pair with passage time of ~20 ps.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Forms in Water by Proton Transfer to a Distorted Electron

et al. 2009

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Solvated electrons are ubiquitous intermediates in radiation-induced processes with their lifetime being determined by quenching processes, such as the direct reaction with protons under acidic conditions. Ab initio molecular dynamics simulations allow us to unravel with molecular resolution the ultrafast reaction mechanism by which electron and proton react in water. The path to a successful reaction involves a distortion and contraction of the hydrated electron and a rapid proton motion along a chain of hydrogen bonds terminating on the water molecule most protruding into the electron cloud. This fundamental reaction is thus decidedly shown to be of a proton transfer rather than electron transfer character. Due to the desolvation penalty connected with breaking of the hydration shells of these charged particles the reaction is, however, not diffusion limited, in agreement with the interpretation of kinetics measurements.

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Independent reaction times method in Geant4‐DNA: Implementation and performance

et al. 2020

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Purpose The simulation of individual particle tracks and the chemical stage following water radiolysis in biological tissue is an effective means of improving our knowledge of the physico‐chemical contribution to the biological effect of ionizing radiation. However, the step‐by‐step simulation of the reaction kinetics of radiolytic species is the most time‐consuming task in Monte Carlo track‐structure simulations, with long simulation times that are an impediment to research. In this work, we present the implementation of the independent reaction times (IRT) method in Geant4‐DNA Monte Carlo toolkit to improve the computational efficiency of calculating G‐values, defined as the number of chemical species created or lost per 100 eV of deposited energy. Methods The computational efficiency of IRT, as implemented, is compared to that from available Geant4‐DNA step‐by‐step simulations for electrons, protons and alpha particles covering a wide range of linear energy transfer (LET). The accuracy of both methods is verified using published measured data from fast electron irradiations for •OH and eaq‐ for time‐dependent G‐values. For IRT, simulations in the presence of scavengers irradiated by cobalt‐60 γ‐ray and 2 MeV protons are compared with measured data for different scavenging capacities. In addition, a qualitative assessment comparing measured LET‐dependent G‐values with Geant4‐DNA calculations in pure liquid water is presented. Results The IRT improved the computational efficiency by three orders of magnitude relative to the step‐by‐step method while differences in G‐values by 3.9% at 1 μs were found. At 7 ps, •OH and eaq‐ yields calculated with IRT differed from recent published measured data by 5% ± 4% and 2% ± 4%, respectively. At 1 μs, differences were 9% ± 5% and 6% ± 7% for •OH and eaq‐, respectively. Uncertainties are one standard deviation. Finally, G‐values at different scavenging capacities and LET‐dependent G‐values reproduced the behavior of measurements for all radiation qualities. Conclusion The comprehensive validation of the Geant4‐DNA capabilities to accurately simulate the chemistry following water radiolysis is an ongoing work. The implementation presented in this work is a necessary step to facilitate performing such a task.

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On the reactions of hydrated electrons with OH⋅ and H3O+. Analysis of photoionization experiments

Cited by 76 publications

References 75 publications

Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV

Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV

Hydrogen Forms in Water by Proton Transfer to a Distorted Electron

Independent reaction times method in Geant4‐DNA: Implementation and performance

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