Liquid water ionization: mechanistic implications of the H/D isotope effect in the geminate recombination of hydrated electrons

Sander, M.; Gudiksen, Mark S.; Luther, K.; Troe, J.

doi:10.1016/s0301-0104(00)00170-1

Cited by 42 publications

(91 citation statements)

References 31 publications

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“…Isotopic substitution potentially provides additional insight into the ionization mechanism by revealing the relative influence of nuclear and electronic dynamics in the ionization process, but only a handful of previous studies examine the isotope dependence of ionization in liquid water. 6,[21][22][23][24][25] We discuss the implications of our results for several possible ionization mechanisms in the context of recent liquid jet photoelectron experiments 26 and cluster ionization studies 2,3 that provide a framework for describing the electronic structure of water.…”

Section: Introductionmentioning

confidence: 79%

“…The onset of this process is not well defined, but in this scenario the H 2 O + cation subsequently decomposes by transferring a proton to a neighboring water molecule while the solvent traps and solvates the electron. 1 Although several estimates place the threshold energy for vertical ionization of liquid water in the range of 8.5-10 eV or higher, [2][3][4][5][6] photoionization can occur for excitation energies as low as 6.5 eV. 7,8 This discrepancy implies that nuclear motion of the excited water molecule plays a key role in the ionization mechanism at low excitation energies, a͒ providing an alternate pathway for electron ejection that does not require direct ͑vertical͒ excitation into the conduction band of the liquid.…”

Section: Introductionmentioning

confidence: 99%

“…13 Other experiments at excitation energies up to 10 eV support the observation that the ejection length increases rapidly above 9 -9.5 eV, 6,14-21 although there are substantial difficulties in comparing previous results due to different methods of reporting recombination yields and the use of different fitting procedures. Further complicating that comparison is the fact that only a few authors specifically examine the energy dependence of the ionization mechanism over a broad range of energies, 6,8,12,14,15,22 and that, with the exception of a recent study at 12.4 eV by one of our groups, 21 there are no reliable data for excitation energies above 10 eV.…”

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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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: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

show abstract

“…2a,b are consistent with this model. The long-lived component of pure water corresponds to a residual DA/A 0 of B1.5 Â 10 À 3 after 1 ns and is assigned to a fully thermalized species of solvated electrons [34][35][36] . The increased residual DA/A 0 of GO-containing samples, when compared with pure water, results from the additional absorption of newly formed rGO.…”

Section: Resultsmentioning

confidence: 99%

Revealing the ultrafast process behind the photoreduction of graphene oxide

et al. 2013

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Effective techniques to reduce graphene oxide are in demand owing to the multitude of potential applications of this two-dimensional material. A very promising green method to do so is by exposure to ultraviolet irradiation. Unfortunately, the dynamics behind this reduction remain unclear. Here we perform a series of transient absorption experiments in an effort to develop and understand this process on a fundamental level. An ultrafast photoinduced chain reaction is observed to be responsible for the graphene oxide reduction. The reaction is initiated using a femtosecond ultraviolet pulse that photoionizes the solvent, liberating solvated electrons, which trigger the reduction. The present study reaches the fundamental time scale of the ultraviolet photoreduction in solution, which is revealed to be in the picosecond regime.

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“…Femtosecond pump-probe experiments have been used to unravel details of the equilibration processes following the trapping by the solvent [5][6][7][8][9][10][11][12]. In addition, picosecond measurements on the recombination kinetics of e − aq have described the ejected electron's migration lengths from its geminate partners [13][14][15][16][17][18][19][20][21][22]. These studies evoke a picture of an excess electron that is at first delocalized in the conduction band and then localizes to the hydrated electron e − aq within about a picosecond.…”

mentioning

confidence: 99%

Direct observation of the collapse of the delocalized excess electron in water

et al. 2014

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It is generally assumed that the hydrated electron occupies a quasi-spherical cavity surrounded by only a few water molecules in its equilibrated state. However, in the very moment of its generation, before water has had time to respond to the extra charge, it is expected to be significantly larger in size. According to a particle-in-a-box picture, the frequency of its absorption spectrum is a sensitive measure of the initial size of the electronic wavefunction. Here, using transient terahertz spectroscopy, we show that the excess electron initially absorbs in the far-infrared at a frequency for which accompanying ab initio molecular dynamics simulations estimate an initial delocalization length of 40 Å. The electron subsequently shrinks due to solvation and thereby leaves the terahertz observation window very quickly, within 200 fs.

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Liquid water ionization: mechanistic implications of the H/D isotope effect in the geminate recombination of hydrated electrons

Cited by 42 publications

References 31 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

Revealing the ultrafast process behind the photoreduction of graphene oxide

Direct observation of the collapse of the delocalized excess electron in water

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